Tech Tip #3 – AC Operation

It’s hot outside! Your BMW’s AC is working hard to keep you cool. Unfortunately, our daily climate in Texas is considered a severe AC system duty area. AC systems are overworked and wear out sooner than expected. A few simple suggestions will help the AC system’s efficiency and longevity.

First, make sure the AC/Heat bias regulator dial, located in the center dash vent, is always on three blue dots.

Second, the AC system should be operated in the recirculation mode by pushing the recirculation button (circular arrow button without the ‘A’). This will close off the hot ambient air, normally allowed to infiltrate the cabin. If the air conditioner is allowed to cool just recirculated air, the cabin will cool down faster and ultimately be much cooler.

Third, the AC system programming is set at the factory to a normal setting for all North American cars. The AC system can be re-programmed to accept a new setting for “hot country” which will bias the AC system sensors, mixture flaps and air flow for maximum cooling.

Ideally, you should follow these steps to make the AC system as efficient as possible. The ultimate benefit will be an AC system that will be able to cycle off more frequently and therefore last longer without repair.

Tech Tip #2 – Check Engine Light

As with a number of components in your BMW, the engine’s performance and operation is constantly being monitored. Depending on your BMW’s year and model, an engine problem will be brought to your attention via an indicator in the instrument cluster and will be displayed as one of the following:

  • CHECK ENGINE
  • SERVICE ENGINE SOON
  • The Outline Symbol of an Engine

This indicator will always display when the car is first turned on to let you know it’s working. It should never be displayed when the engine is running. If it is, there is a potentially serious running problem that should not be ignored even if the car still starts and runs. Unfortunately, this telltale light will only come on after a problem has existed for a period of time. It is a last resort “cry for help” from the engine management system which can no longer substitute a value or compensate for the problem.

The source of the problem must be diagnosed by starting with an interrogation of the engine management system to read out and interpret the stored faults.

Tech Tip #1 – Engine Operating Temperature

It is vital that your engine reach its normal operating temperature as quickly as possible. This is especially true during this time of year when we experience the coldest temperatures.

An engine that is operating at the correct temperature will:

  • Reduce potential engine wear
  • Improve fuel economy
  • Prevent catalytic converter damage

If your car does not reach its operating temperature (3/8-1/2 way mark on the gauge) within ten minutes of driving, then the thermostat might not be properly functioning and will need replacement.

For more info about cooling systems, read Mike’s article on plastic embrittlement.

It’s Not Enough to See the Light

By Mike Perkins
BMW CCA/Houston Chapter Technical Advisor
Owner – Bavarian Machine Specialties

Imagine you are driving to work in the early morning rush hour traffic. It’s still dark and it’s rainy but the freeway traffic is moving along smoothly. Suddenly you notice a change in something. Your BMW is loosing power! A quick glance at the instrument cluster reveals no warning lights and the fuel is still half full. As you frantically scan the mirrors and glance over your shoulder for a quick maneuver to the side of the freeway, the car dies. You’re left stranded, sitting on the side of the road as cars fly by at 70 mph. You attempt to put the hazard lights on but, they too don’t seem to work. As you sit there waiting for help or a tow truck, thoughts come to mind of how late you are going to be and how this will strain your already busy day. You also start thinking about the last time your BMW was serviced but more importantly, how something like this could happen. After all, you take your BMW in when the lights tell you to…

The scenario you have just read is real. The car is a 2002 530i with 33,000 miles. When this new customer pressed me for the underlying reason why she had been stranded, I candidly told her, “lack of maintenance”. When I asked about her service history she explained how good she was about taking the car in when the Service Interval System told her. In 4 years and 33,000 miles, the car had only been in for service twice, once for an oil change and again for the newly stripped down Inspection I Service. With her current lifestyle and busy schedule, she was wholeheartedly willing to accept a minimalist approach to caring for her car, especially if it was backed by the manufacturer. She was convinced BMW’s do not need as much attention as they did even 3 years ago. It was then that I tried to enlighten her that “Free Maintenance” came with a price – you pay for it up front with the purchase of the car and again after it expires to make up for the neglect.

It seems as though vehicles are expected to run perfectly every time they are driven. For the most part, BMW drivers take their cars reliability for granted. There should be one more Law of Physics lesson taught at an early age – machines require maintenance. BMW owners rarely envision a lack of preventive maintenance as causing reliability problems with their ultimate driving machine.

A good case and point is this customer’s 530i. The car had an original battery which was no longer capable of offering a reserve storage charge. It was only capable of starting the car solely on its surface charge and as long as the alternator maintained the appropriate 13-14 volts in the electrical system, everything functioned fine. Keep in mind the failing battery required constant charging thereby placing a continuous load on the alternator. As this customer drove along, she unknowingly placed a depleting load on the charging system and battery by running a number of accessories (lights, wipers, A/C, etc.) due to the driving conditions. These accessory loads coupled with the battery charging requirements may normally have worked the alternator to its maximum capacity but not caused a failure. Unfortunately the alternator was already destined to fail; not because of age but because of lack of simple maintenance. All modern alternators require cooling. The alternator of this model is air cooled, as are a number of other BMW models. The alternator has to dissipate the heat generated during charging or it will eventually fail from repeated overheating. During this car’s history, leaves and other road debris have been sucked into the alternator cooling duct and then become crammed into the back of the alternator preventing proper air flow.

alternator_560

The load placed on this car’s charging system that day was too much and when the alternator failed, the battery could offer no assistance and the car ceased to run. This is just one of many situations that I have experienced in the last few years that could have been easily prevented if a sensible level of maintenance was performed.

A simple maintenance item that is now commonly neglected is the fuel filter. Fuel filters that used to be changed at 15,000 mile intervals must now provide fuel system protection for at least 60,000 miles. These filters are expected to last for that period of time although no appreciable design change has transpired. More importantly, the lack of servicing allows possible fuel contaminants to go unchecked. Added cost, poor fuel mileage and sometimes engine damage are all the results of this poor maintenance approach.

At my shop, we regularly change air filters at 20,000 mile intervals due to the enormous accumulation of silt/grit clogging the filter. Air filters protect engine cylinder walls, pistons and piston rings from ingesting grit that would ruin an engine in a very short time period. The new style paper air filters with an added layer of foam are expected to last up to 60,000 miles. As well as contributing to poor fuel mileage, the long term ramification is an engine that may start burning oil by 80,000 miles because of the grit that makes it through the filter.

Aside from engine wear, extending air filter change intervals contributes to air mass meter problems. The sensitive air mass meter is located directly downstream of the air filter and can be greatly affected in its operation by just a film of dirt. This meter is the determining sensor for the engine air/fuel ratio and once its readings are off, a host of problems will develop. It is not uncommon to see fuel trim adaptation values beyond limits, engine stumble, hesitation, or even cylinder misfires.

Some of the more complicated examples of preventative maintenance include testing the car electronically. Indicators of problems that have not illuminated the Check Engine light/Service Engine Soon light lurk behind the scenes creating changes of which the driver is unaware. These may include adaptive values, sub-system faults or even control unit programming updates. These can sometimes lead to expensive problems but if uncovered early enough, can prevent additional cost or breakdown.

So why is it that cars are only serviced or repaired when an indicator comes on? There are many reasons but one main reason is because as maintenance packages have been introduced, dealers have urged BMW owners to “just follow the service interval system”. Most owners assume that this means the car has a proper maintenance agenda. But who’s agenda? A marketing department who is only interested in getting the car through the warranty period; or you, who expects such a well engineered machine to last for at least 150,000 miles?

If you look at what dictates a maintenance schedule, you will find it is based on the oil change interval. As synthetic-blended oils have been introduced, oil change intervals have been extended thereby pushing back other maintenance necessities. It is not hard to appreciate that when one small problem goes undetected, it will invariably have a domino effect on other components adding to the overall cost of repair. Too often, service programs such as the Inspection II are interpreted by BMW owners as a superfluous list of checks and simple replacements for the here and now. In reality, the checklist is not intended to be black and white. The overall importance is to read between the lines and identify possible problems that will lead to added expense or inconvenience in the miles to come.

Keep in mind the BMW service interval system uses a math model to infer the rate of oil degradation based on collected data. This software based maintenance reminder system is at best a prediction because it cannot directly measure the condition of the oil or detect the presence of contamination. Engine maintenance requirements can also be greatly influenced by ambient air conditions, fuel formulations and by the actual condition of the engine.

Changing oil more regularly can pay off in the long run but it can also equate to draining a lot of serviceable oil. BMW has tried to address this and the environmental impact by using better oils and extending the service interval system mathematical parameters. However, consider that in the span of a decade we have gone from a 3000 mile oil change to a 20,000 mile oil change interval. Because of this, I routinely see engines at 45,000 miles that have had two oil changes and are so gunked up that the engine will have serious problems with lifters, rings and bearings before the 60,000 mile mark.

gunk_560

As a general rule, we recommend oil changes depending on each customer’s driving habits. Usually the mileage period for changes is 5000 to 7500 miles. We arrived at this range based on laboratory analysis of oil we drained from customer’s cars.

For comparison, the following picture is of an engine with 82k that we have serviced for its life time.

no_gunk

As an aside about oil changes, lately I have seen an unfortunate trend of poorly made off-brand oil filters installed in relatively new cars. Not only are these filters doing a poor job of filtering oil, but with the extended oil change intervals, they are literally disintegrating, adding to the contamination of the engine. When questioned, the customer usually admits to visiting a nearby quick-lube store. No maintenance program is worthwhile without quality parts.

Pro-active repairs have been replaced by a reactive minimalist approach because in the short run, it costs BMW less and is more convenient for you. Plainly put, it’s what works when selling cars. Behind the scenes is a different story. People I know in the industry from the dealer level to the aftermarket community (including engineers) would never subject their own cars to such an insufficient maintenance schedule. BMW’s service interval system is set up for one type of ownership and it is not intended to protect your BMW for the second half of its life. When you consider that there is nothing exceptionally difficult about an accelerated approach to maintaining your BMW, the added years of return will justify the effort.

To Start or Not To Start

By Mike Perkins
BMW CCA/Houston Chapter Technical Advisor
Owner – Bavarian Machine Specialties

About this time of year, I see a more frequent occurrence of engine cranking problems in the shop. Once the ambient temperature starts to drop, the starting circuit gremlins come out. Generally, there are two kinds of cranking problems: no-crank and slow-crank. The slow-crank problems are tougher to diagnose and are usually the result of more than one problem. In this article, I will describe some simple procedures to help troubleshoot problems with the battery portion of the starting system, as well as the proper way to jump start any BMW.

A good plan for troubleshooting any poor cranking problem should start with a strong word of caution. Don’t jump to any conclusions. Too many times a battery is replaced only to have the starting problem return within the first week. Begin with the simple things first. Are there any visibly bad connections at the battery terminals, starter solenoid or ground connections on the engine block? Check to see that the alternator belt is not loose and therefore not providing a sufficient system charge. How about the condition of the battery terminals? Are the terminals coated with a build up of corrosion? Are the terminals secure? Is the battery filled to the proper level with electrolyte? Is the battery even the correct size and type for your BMW? Check the cold cranking amperage (CCA) rating of the battery and compare it to the recommended size listed in your owner’s manual. If all of these things are good, then you may simply have an old or weak battery. However, if the battery is relatively new (2 years or newer) and won’t crank the engine, you may be facing a number of gremlins that are causing the battery’s weakened state. Some examples might be an alternator or voltage regulator problem, a starter motor or starter bendix problem or the dreaded parasitic electrical system drain.

The most logical thing to do at this point if nothing simple is found is to test the battery. You need to eliminate a few of the unknowns and the battery is the best place to begin when dealing with the starter circuit. The battery must first be eliminated as the problem since it provides the voltage needed to force current through the starter motor. Without sufficient voltage, especially under load, any other tests will be inaccurate.

On batteries with removable caps (older BMW batteries and most aftermarket replacement types) look for a bad cell. Remove the caps and watch the cells while a helper cranks the engine. If any cell “boils” when you try to start the engine, you are done – and so is the battery. (Please protect your skin and eyes when working around any battery). If there is no boiling, you will need to check each cell with a hydrometer (available for under $15.00 at any local parts store). Uniformly low readings may simply mean the battery is discharged, through no fault of its own. If specific gravity is below 1.225 on all cells (75% of full charge), the battery needs to be recharged before further testing. It is too weak to crank the starter at the proper speed. To recharge the battery, disconnect the battery from the car’s electrical system and hook it up to a charger. Overnight on a trickle charger should bring a discharged battery back to good condition (an inexpensive 12 volt charger can be purchased at any number of stores and should be considered a must in everyone’s garage). If one cell in the battery is 50 points lower than its neighboring cells, that cell is bad, which usually means the battery is bad. Specific gravity readings above 1.225 in all cells mean the battery is healthy and not the problem.

But what if the battery has no removable caps? All newer BMW and certain aftermarket batteries are made this way and sold as maintenance free batteries. Unfortunately, like most things that claim the maintenance free label, they just don’t seem to last as long as something that receives a minor amount of maintenance. An accurate digital volt ohm meter (DVOM) is needed to check the state of charge in sealed-top batteries (also available at a number of stores at less than $50.00 and is useful for most anything electrical around the house). Measure no-load voltage across the battery posts. If the reading is lower than 12.45 volts (75% of full charge), the battery must be recharged before testing. No-load voltage of 12.45 volts or higher, measured across the posts, means the battery is strong enough to properly operate the starter.

If the battery is uniformly discharged, you may be tempted to slap a new battery in the tray, without any more diagnostics. Don’t do it just yet. What you don’t know at this point is why the battery is discharged. If it’s just plain tired and that is the only problem, the new battery is certainly a part of the fix you’re looking for. But if the old battery died an early death because the charging system couldn’t keep if fully charged or there is a system drain, then a new battery certainly won’t do any better after a short period of time.

If the battery was recharged and appears to have a good post to post no-load charge, then its time to find out how good it really is. After charging the battery, the artificial surface charge on the battery must be removed by applying a load to the battery. You can do this by simply reinstalling the battery and turning on the head lamps for two to three minutes. Disconnect the battery and recheck the post to post no-load charge. If 12.45 volts or higher is indicated, you are ready to load test the battery. Since an accurate battery load test requires a fairly expensive variable load tester, it is best to find someone to do this for you. Remove the battery from the car and transport it, preferably in a plastic container. (Note: A clean battery, void of acid build up or leaks, will always be appreciated by the testing facility. Also, remember that battery acid/corrosion eats through clothing and car interiors. This will also give you a chance to clean or neutralize the battery tray in the car). Any shop/store selling batteries will load test your battery, usually for free. Have the battery test performed with a load equal to one-third of the battery’s CCA. The test should last at least 10 seconds but no more than 15 seconds.

If the battery reading is less than 9.6 volts with the electrolyte at 70∞ F, the battery is no good and should be replaced. Changes in temperature of the electrolyte will affect acceptable voltage levels. A good rule of thumb is to deduct 0.1 volt for every 10 degrees in temperature of the electrolyte. For example, at 40∞F, the battery can read 9.3 volts after the load test and still be OK If the temperature is above 70∞F, add 0.1 volt for every 10 degrees. Optimally, you would like to see 10.0-10.5 volts from a strong battery.

After reinstalling the battery, if the cranking speed is good, the discharged battery was the starter circuit culprit. Although the starter circuit may be working properly, you must now determine why the battery was discharged. Your next step is to check for an electrical system drain. The easiest way to do so is to connect your DVOM in series between the negative battery post and negative battery cable end. Set the meter on the 10 amp scale and make sure you have an artificial drain on the system. For example, if the battery is located in the trunk and the trunk lid is open, make sure the courtesy light is not on and that the contact switch is off (depressed). This applies to a door contact if the battery is under the back seat, or the hood if the battery is in the engine compartment. Remember that some cars have alarm contacts under the hood and back seat. These should also remain in a normally closed position, especially if you are testing the alarm system in an active mode as part of the electrical system drain.

With the car shut down, key out, and all contacts closed, the normal drain on the system should be 20 – 30 mA with no more than 60 mA on the latest larger systems. Make note that most cars take several minutes to settle out. Initially, you might think you have found, for example, a 2.4 amp draw only to see it disappear after all relay or general modules shut down.

If all readings during an electrical system test look good and there is no appreciable drain on the system, then you are left with one of 2 situations. Either you have an intermittent electrical drain or a charging system problem. Both of these problems are best left to a professional with equipment and expertise to properly troubleshoot.

If you find yourself in the position of needing to jump start your car, my best advise is don’t. Not only should you not jump start your car but don’t jump start somebody else’s car. The possibility of damage to certain electrical components from a voltage spike installing or removing jumper cables is too great. The best method is to disconnect the battery cables and charge the battery.
However, in certain circumstances jump starting may not be avoidable. To protect the electrical system in your car, follow these simple procedures to reduce the risk of damaging sensitive electrical components.

  • Make sure neither car is touching.
  • Ensure that both cars have batteries of the same voltage and approximate amp hour rating.
  • Take care to avoid arcing of the jumper cables on the positive or negative posts.
  • Connect the positive jumper cable first to the vehicle receiving the jump and then to the vehicle providing the jump. All newer BMW’s have a B+ junction post under the hood that should be utilized. Avoiding spark around a battery is a good idea for obvious reasons.
  • Connect the negative jumper cable to a chassis ground first on the car to be jumped and then on the car used to jump start. Most newer BMW’s also provide a ground lug usually located on either the front fenderwell or shock tower.
  • There is no need to start the engine of the car providing the jump start.
  • After double checking all cable connections for secure contact, attempt to start the car with the weak battery.
  • After the vehicle starts, allow it to run for a minute with the cables connected. Then switch on the headlights or heater blower prior to disconnecting the jumper cables. This will minimize the voltage surge the moment the cables are disconnected.
  • Disconnect the negative jumper cable leads from both cars and then disconnect the positive cable.
  • If used, make sure the B+ junction post is securely recovered to prevent inadvertent shorting.

Starting problems always seem to happen without warning because unfortunately, like most things that seem to work fine, we ignore them until they discontinue working. Keep in mind that a battery with a minor amount of attention should last for at least four years. The lesson, as always, is that with a little preventative maintenance you will not be stranded in a potentially inconvenient situation.

It’s Always the Little Things

By Mike Perkins
BMW CCA/Houston Chapter Technical Advisor
Owner – Bavarian Machine Specialties

When I first started in business a friend, worried about my stress level, took me aside and told me: “Don’t sweat the small stuff.” Over the last twenty-five years I have learned that his advice was simply wrong. From my experience, if you don’t sweat the small stuff you will soon be sweating much bigger problems. Like a row of dominos, seemingly little car problems have a way of compounding themselves into major system or reliability issues. With just a little bit of attention, caring for some of the following “little” issues will keep you from having bigger problems.

Clogged Body Drains

An easily preventable problem centers on clogged body drains (the small drains that allow rain and carwash-water an escape from the body). Drains in the cowling area, sunroof, and convertible top storage compartment are seldom inspected and without attention they can lead to a major calamity. Those who park outside, especially under trees, beware: leaves and debris are easily trapped in key drainage areas, and if allowed to decompose, will completely clog the drains.

If you allow the cowling drains (those at the base of the windshield under the hood) to clog , expect soggy front footwell carpets after a hard rain as the water winds its way through the heater box seal and into the car. If this condition goes undetected your soggy carpets will not only mold, there is a good chance your air condition control unit and wiring will corrode and fail. Imagine a moldy, non-air conditioned car simply due to leaves in the cowling drains.

Clogged cowling drains also can flood the passenger footwell area, the water instead flows to the area housing the engine management control unit (DME) which, at best, causes a non-start condition until the unit dries (or at worst a totally “fried” DME). Perhaps you or one of your friends have experienced a non-start after running your 3-series through a car wash (check those cowling drains).

Surprisingly, sunroof drains are notorious for clogs. A clogged sunroof drain leads to soaked headliners and or ruined leather seats. A quick check of the drains can be performed by pouring a small cup of water into first one corner, then the other corners of the sunroof channel. If clear, you will see the water pool beneath the car behind both the front and rear wheels. If you find a clogged drain be careful using compressed air to clean the blockage: sunroof vent tubes are pressed-on to plastic tubes that can pop off if the clog is stubborn.
Clogged drains in the convertible-top storage areas of some cars are also problematic. One customer of ours regularly parks beneath a Live Oak Tree. After a week out of town (when it rained heavily) he returned to find a thoroughly soaked back seat and two inches of standing water in the footwells. Initially he thought the convertible top leaked, but upon inspection the culprits were completely clogged drains in the convertible top storage area. As the storage compartment filled with water it overflowed into the backseat and onto the floor.

Air Flow Blockage

Clogs present a different problem having to do with air conditioning and engine cooling. Some cars tend to trap road debris in the lower air conditioner condenser area. Paper, leaves, and other road debris collect between the auxiliary fan and condenser causing a number of heat dissipation issues. The clogged condenser area creates super-heated air that affects radiator cooling, auxiliary fan operation, and eventually air conditioner compressor life. A good cleaning of the condenser once every couple of years will help alleviate these potentially expensive situations.

Paper, leaves and other road debris cause problems with some BMW’s that have an alternator cooling duct (especially those with low inlets). Pop the plastic cover off the back of the alternator some time and you will think some rodent built a nest in your alternator. We have found all manner of paper, twigs, leaves, feathers, and even cigarette butts crammed into the back of the alternator. The ducting acts to cool the alternator’s diode plate and is needed especially on later model cars with higher amperage alternators. Heat build up has become such an issue that BMW engineers have tried water cooling the alternator. Unfortunately, in my experience the only time the alternator cooling duct is cleaned is after an alternator failure and the expensive new alternator is installed.

One final clogging problem for now: As everyone knows, the most efficient way to operate the air conditioning system in the hot, humid Houston climate is in recirculation mode. However, be aware that on some cars this can lead to a clogging problem with the integrated heating and air conditioning system (IHKA) internal recirculation filters. These IHKA filters are not to be confused with the external-air micro filters (which should be replaced at regular intervals as part of routine service). When these internal IHKA filters become clogged they impede air flow through the air conditioning system including the blower motor and final stage If no attention is paid to the IHKA filters the result will be a 12-hour job to remove the dash and replace a burnt out blower – all for the sake of two small filters. When you replace these original filters for the first time, especially if you have a pet that travels in the car, wear a mask and gloves because it won’t be pretty. You won’t believe what you’ve been breathing

Engine Cooling System

Engine cooling systems can present a host of little problems that, when not properly addressed, can lead to an expensive failure. One such problem that stands out in my experience has to do with the lack of concern for the corrosion of aluminum parts, especially where oxygen may come in contact with coolant. The perfect breeding ground for this kind of corrosion is at the mating surface on the cylinder head for the thermostat housing. Time and again I have encountered coolant seepage at the thermostat housing only six months following a thermostat or thermostat-housing replacement because no attention was paid to the “minor” corrosion under the profile gasket. This corrosion may look innocent enough in the early stages but by the time the corrosion has festered, you will end up with a pitted aluminum cylinder head that cannot be sealed by normal means. Removing the head for welding repairs is an extreme measure we have had to take, all for the lack of a little extra effort during the initial repair.

Engine Oil Service

Have you had the opportunity to see inside a motor serviced under the current BMW factory recommended maintenance program? An internal coating of sludge will be found inside a 45,000-mile engine which has received only the recommended two oil changes. Changing oil more often is seemingly such a little thing but it has so many benefits for the longevity of your car’s motor. The valve train, especially hydraulic lifters, cannot survive in such a filthy environment. How many of you have heard that tell-tale tick, tick, tick on start up? Noisy lifters are directly related to the internal cleanliness of the engine. Just because BMW only pays for one oil change every 15,000 miles, don’t believe that is everything you need – common sense can prevail.

This is just the tip of the iceberg when it comes to my list of “little” things that, without regular attention, can lead to costly and potentially disabling repairs. Yes, what is here will help prevent future problems but more importantly, it helps to point-out the benefits of tackling the “little” things now, rather than paying for expensive crisis management later. As another friend of told me: “An ounce of prevention is…..” well, you know the rest.

Round & Round We Go

By Mike Perkins
BMW CCA/Houston Chapter Technical Advisor
Owner – Bavarian Machine Specialties

“How can my steering wheel still shake!” she exclaimed. “I’ve had the tires balanced several times and even had the alignment checked.” Does this sound all too familiar? This is one of the most common complaints I see, and unless properly addressed, can lead to expensive front end repairs, or worse, a loss of driving enjoyment from ones BMW. Her 1997 528i recently had new tires installed and thereafter developed a slight shimmy, nothing big, just an annoyance in the 50-60 mph range. 2000 miles later, the car had a full blown steering wheel shake. How can this seemingly simple job of mounting and balancing tires end up becoming such a problem situation? Simply put, there is a lot to having the job completed successfully. This article will point out some of the basic concepts involved in achieving the smoothest ride and longest term tire wear from your BMW. When diagnosing and correcting front end related vibrations, there are three major areas that must be investigated. These areas are steering and suspension components, tire and rim run-out, and tire and rim imbalance.

Part I – Steering and Suspension Components

It is essential to start with an initial inspection of the front end steering and suspension components. Minor wear in suspension bushings, ball joints, tie rods, center links, idler arms, or steering gear can amplify or even induce a front end shimmy. For example, weak front shock absorbers are the classic problem when it comes to irregular tire wear. Tires that exhibit a “scalloped” outer edge or are extremely “cupped” in places are the result of shocks that can not handle the bounce of the wheels. This can also be a cause and effect issue. By virtue of an out of balance tire, the shock wears out prematurely. Wear or play in any component can only be detected by a detailed inspection of each piece. A push/pull or clamp/release method is usually employed to test joints for wear. However, it must be recognized that if a car is on a lift with its wheels hanging down, there will be a different joint reaction than one on a lift that leaves the wheels in a loaded position. Generally speaking, Houston roads are brutal on a highly tuned and responsive suspension such as that found on BMWs. It has become the norm to see worn out shocks, ball joints, and broken bushings by 60,000 miles. The nimble suspension we all appreciate degrades quickly without upkeep and will definitely wear your tires.

Tire pressure has a major influence on tire wear and can influence tire bounce especially if the tire is over-inflated. A simple rule of thumb: For every 10∞F of temperature change, your tire pressure changes 1 psi. The pressure increases with higher temperatures and conversely with lower. It is best to only check tire pressure when the car has not been driven or has not been sitting in the sun. Each BMW has a handy little label on the driver’s “B” pillar (inside the door jam) giving you a recommended tire inflation pressure to follow. Just 2 psi can make a big difference.

A component that can greatly affect tire shimmy or shake is a worn wheel bearing. Usually a BMW wheel bearing will let you know when a problem exists by a growling noise above 25 mph which is especially noticeable when driving on smooth pavement. This noise is not be confused with a tire roar from uneven tread wear. Some tires, because of tread design, are inherently louder and actually worsen with mileage due to the “blocky” tread design. This kind of tire requires more frequent rotation.

Another kind of shimmy is when the brake is applied at speeds above 50 mph. If you are thinking rotor shimmy, you would be partly correct. Add another dimension to it and you have rotor induced suspension shimmy. This is where the applied braking force collapses the strut arm bushings and starts an oscillation that produces a perverse front end shake that makes it seem like the dash is vibrating.

A last item I consider part of the steering and suspension category is the overall alignment. Many times I have been asked to check the front end alignment because the steering wheel has a shimmy. From experience, I know that no amount of re-aligning the front end of your BMW will change the degree of steering wheel shimmy. A properly aligned car will help prevent a shimmy problem down the road by keeping tires wearing evenly but it will never correct the actual shimmy. This is definitely a cause and effect issue.

Part II – Tire and Rim Run-Out

The second area that must be investigated is tire and rim run-out. This is the most common and most overlooked problem. Tire and rim run-out are identified as radial and lateral run-out. Radial run-out is an excessive amount of “hop” in the wheel and lateral run-out is an excessive amount of “wobble” in the wheel. No matter how well a wheel is balanced, it will always cause a vibration if either type of run-out exists. This run-out can be a bent rim or simply a tire that has not retained its original round shape. New tires can even have excessive radial or lateral run-out. It is a prerequisite for the person installing your tires to test for any rim run-out. This, unfortunately is where the job has problems before it even gets started. The rim must be measured with a dial indicator to identify any problems. Minor rim run-out can be accepted if the rims are to be used in the rear of the car but must be marked to avoid future problems when rotating. Rims to be used on the front of the car must have less than .040″ run-out as measured on the inside of a dismounted rim lip. This means the person installing your tires must dismount all the rims and pick the best two for use on the front of the car before even considering tire mounting. However, some rims on late model BMWs are of different widths. If any rim in this case exceeds the maximum run-out, the rim can possibly be straightened and then installed in its original position.

Once the tires are mounted, the radial and lateral testing process must now be applied to the tires. Tires must not exceed a limit of .060″ run-out after final mounting. If not, a process of phase matching should be used. This process corrects for radial or lateral run-out in tires. Dismounting the tire from its wheel position and remounting it matching the minimum tire run-out point to the maximum rim run-out point will produce a rounder tire/wheel combination. In some extreme cases, a new tire is required. To further complicate this situation, most higher performance tires are pre-marked for mounting position. Specifically, the manufacturer has indicated a mounting position in reference to the valve stem. A relatively new style of balancer has been marketed by Hunter which actually applies a rolling force to the tire to measure uniformity of the wheel. This is the latest in balancer technology and certainly helps the operator obtain a true balance.

Part III – Tire and Rim Imbalance

The third major area of concern when investigating a front end vibration is actual tire or rim imbalance. All wheels must be balanced using an on-the-car or off-the-car dynamic spin balancer to achieve any decent level of overall balance. There are many good brands of balancers being used in shops today and most are off-the-car types. However, the key to receiving the best job still lies with the skill of the technician. Balancers can be set to read in grams or ounces, rounded or precise numbers, and display at least four different positions where the weight can be placed on the rims. Wheel weights also come in specific profiles to exactly fit the rim lip. You must be sure the shop has the correct style weight to fit a BMW rim, otherwise they will fly off and you will immediately develop an imbalance. The factory 2 piece wheel weight is always a very good system, although very few places use them because of the cost and additional time to install. There is also no way of hiding a factory weight on the inside of the wheel as you would a tape weight. For those of you who prefer that the weight not be visible, please realize not only does it take more weight when located in the middle of the rim, but the wheel balance will never be as accurate. Every wheel has 2 planes for balancing, the inside and outside of the wheel on the outer edges of the rim. The idea of balancing a wheel is to use the least amount of weight (usually below thirty grams) and in the most accurate position. To achieve this, stay with the conventional style of balancing, one weight on each side of the wheel. When I am confronted with a rounded or polished outer rim profile, I will use a “drop center” method (hiding the outer weight behind the spokes) but still maintain the inner weight in the normal position. In addition to having the weight in the correct position on the rim, it is imperative to use the exact amount of weight needed. Many shops that balance wheels allow the balancing machine to operate in a “round off” mode. This means there is a margin for error of + / – five grams. Therefore, your wheel might be ten grams out of balance on at least one side of the rim and yet show the operator it is perfectly balanced. This allows for quicker balancing but over time and mileage, the tire will show the negative results of an imprecise balancing job. Have your wheels balanced to non-round off specs. If you really want to see if a good job is being done, look for a digital scale next to the balancing machine that the operator uses to check the weights he trims by hand! As long as we are being picky, make sure all pebbles are removed from the tread prior to balancing. Another thing to mention about balancing machines is the way the wheel is attached to the balancing arbor. Most machines and shops use a cone which lends itself to inaccurate readings. A finger type hub that engages the tapered lug holes is a much more accurate method of attachment. These hubs are expensive but an excellent investment for a dedicated shop.

Two tire balance situations come to mind that should be avoided. Anytime you use a liquid fix-a-flat product consider the tire to be worthless. It either hardens on one side of the tire, or never hardens and continually changes the tire balance. In either case, it is next to impossible to balance. The second situation is a warning about gas stations that do not drain their air compressor (air compressor tanks fill with water from the hot air condensing and the tank needs to be maintained). Each time you fill your tires with air from one of these compressors, you will also add a small amount of water into your tires. You can guess the result, so make sure you have a reliable air source.

On a final note about balancing tires, I strongly advocate rotating and balancing wheels every 6000-8000 miles. It is within the normal scope of everyday driving that tires and rims will change shape and balance, not to mention hitting pot holes, railroad tracks, or broken concrete. For those of you who have either different size wheels (front to rear) or directional tires, you can still at least rebalance on a regular basis without rotating. It is also a viable option to dismount your wheels and swap the tires from side to side. It is understandable how someone might think “How hard can it be, it’s only tires?” This might be true when it comes to a truck or a car with a less sophisticated suspension. However, what makes the cars you and I drive so special is the precise nature in which a BMW commands the road. To expect that level of precision requires a mind set above the average approach to a seemingly simple job.

Embrittling Experiences

By Mike Perkins
BMW CCA/Houston Chapter Technical Advisor
Owner – Bavarian Machine Specialties

There are times I believe all of my new customers are predestined to end up on my doorstep due to an angering experience with their BMW. In this particular instance, the potential customer was moving from San Francisco to Houston. She had just received a thorough Inspection II from a reputable shop in the Bay Area and was secure in the belief that her 1997 328i was in completely reliable shape. A little more than 100 miles away from Houston, without any notice, the car experienced a severe overheat problem. Within seconds, the temperature gauge shot into the red and steam poured out from under the hood. She did the correct thing by immediately pulling off the road and shutting the engine off but as she sat stranded on the side of I 10, she couldn’t help but wonder how her well-maintained car could have done this to her. The type of problem she encountered is something you have either experienced, heard about, read about, or will have happen to you if you own a 10 year old or newer model BMW.

Up until the last decade, I would have been accurate in my initial phone diagnosis by presuming a coolant hose had popped. However, as of about 1991, BMW entered the new age of the latest technology in plastic injection molds. Plastic is a wonderful innovation; it has improved everyone’s life in someway. With this in mind, I do not mean any disrespect to the purveyors of plastic when I say in some cases, plastic is a cheap substitute. Plastic parts in automobiles have been touted for saving weight and improving the overall design. However, I would suggest that the biggest net gain is not the durability of the product, rather the ease of manufacturing and the associated costs. This fact alone should be upsetting and is certainly part of the trend. Technology is great when the consumer receives a better product at a lower price. However, when the product is cheaper to manufacture but costs the end user the same or more and doesn’t last as long, it is simply a manufacturer’s problem.

The 1997 328i did what so many other BMW’s I’ve seen have done. The coolant hose to the radiator didn’t “pop” or even come loose, the neck of the radiator that the hose attaches to simply broke off. This problem is far too common on all models since the early 90’s and is what BMW refers to as “plastic embrittlement”. The plastic has heated up and cooled down enough times to create a brittle condition in the plastic of the radiator. Add to this condition the stress of an upper radiator hose that lightly tugs at the radiator neck every time the engine revs and eventually the plastic will snap off. Almost all of the coolant is purged from the system rather quickly at this point and for those who think they can make it to the next exit or the gas station, the decision is usually fatal for the motor. I have seen this type of failure on cars that are just 4 years old. Be advised that this “plastic” problem is not limited to just the radiator. On any given model there are at least 5 plastic “time-bombs” waiting to go off and that is just in the engine cooling system. The disturbing part is that it seems that BMW or its’ plastic manufacturers have forgotten how to make plastic. For example, the first plastic tanked radiators were used on a 1979 528i. These radiators were never replaced for this same problem and usually lasted 10 years. Eventually, when we did replace them, it was because the crimp seal was leaking or we couldn’t properly clean out the core. This brings up another issue, you don’t “rod out” plastic radiators (as you did with brass radiators), so every year the heat dissipation problem becomes a bigger concern, and in Houston, that puts the car at a disadvantage. In my shop, cooling system plastic parts are now viewed as “wear items”. This means cooling system parts that are susceptible to sudden failure have a replacement cycle much like you would do with brake pads.

Consider the following list of cooling system wear items to be susceptible after 4 years or 50,000 miles:

  • Radiators on all models should be inspected and tested for cracks in the plastic tanks and especially around the upper hose connection. Most will need replacement to be safe. Some Behr replacement radiators are available with an aluminum collar inside the neck to reinforce the stress area. There are also aftermarket radiators that have no plastic but have proved to have other reliability issues. In addition to radiator neck problems, 96 and newer 7 series cars also suffer from a leak around the o-ring at the plastic hose fitting. Replacing an entire radiator because of seepage around an un-fixable fitting or a suspect radiator neck is a tough pill to swallow but carefully consider the alternative.
  • Water pumps on all M50/M52 engines manufactured up until 10/96 on 3 and 5 series cars came with a plastic impeller. Most of these have either been replaced by now or have self-destructed. If you still have an original water pump, have it removed and inspected. The impeller splits along the water pump shaft and the impeller will generally “freewheel”. This causes an odd heat up problem that is usually mis-diagnosed as a faulty thermostat. In extreme cases, the impeller simply disintegrates leaving lots of little plastic pieces throughout the engine cooling system. BMW upgraded all of these pumps to a stamped steel impeller but third generation pumps now have a composite material impeller. Time will tell.
  • Coolant reservoirs on all models have a tendency to warp and to even split open. 5 and 7 series up through 1995 will split along the seam and the steel collar inside the reservoir hose neck will work its way out allowing the neck to break off. Reservoirs on 3 series will warp around the cap area and not seal against the cap o-rings properly. In extreme cases, coolant will stream out around the cap after the car is shut off as the cooling system heat soak quickly builds. 96 and newer 7 series reservoirs break apart internally and eventually split open.
  • Fan shrouds on all 5 & 7 series cars will simply crumble to the touch after several years. In extreme cases, a piece will come off, hit the fan blade, and become a projectile (hopefully missing the radiator).
  • Thermostat housings are an especially sore subject depending on which model you own. For those who own a 99 and newer 3 or 5 series car with the M52 TU engine, you know what I mean. The plastic thermostat housings were not reliable and by now almost every one has been replaced under warranty. On 5 and 7 series cars, up to 1995, plastic thermostat housing covers split and leak along the seam and can be mistaken for a water pump leak. All E36 3 series thermostat housings are a plastic composition which will eventually crack. It is interesting to note that there are aftermarket replacement housings available in aluminum if you don’t want to install the plastic part. BMW has even gone back to aluminum thermostat housings in some cases, such as 1996 and newer 7 series.
  • Auxiliary water pumps on all 5 and 7 series cars are also plastic. They are notorious for breaking off at the inlet hose neck. Added heat from the engine exhaust manifold and tension from the hose exacerbate the problem.

It is important to note that once an overheat condition occurs the embrittlement effect is accelerated due to extreme thermal loading. In other words, when you have one overheat situation, fix the system, not just the failed part, especially if the car is already within the window of susceptibility. It has been suggested to me that a five year old BMW is an “older car” and this kind of situation should be expected. My point of reference, however, is conditioned by the large number of customers who drive 10 year old BMW’s and expect it to be as reliable today as it was new. If this kind of failure is to be expected, it is my job to alert people of the potential issues, averting any inconvenience or added expense.

BMW is not alone with its plastic woes. All manufacturers are using more and more plastic to fit where traditionally cast aluminum was doing the job. For example, intake manifolds on a majority of BMW engines are a plastic mold. These pieces warp or crack causing engine vacuum leaks, running problems, and check engine lights. Yes, they are lighter but the resonance from valve noise through the plastic manifolds is a lot louder which requires additional sound insulation. There are always trade offs as cars evolve and we should make ourselves aware of the positives as well as the negatives. I fear the trend is for all manufacturers to further the plastic snap together process. Consider the numerous engine, interior and body trim pieces that are now plastic. Removing snap-in plastic pieces after 5 or 6 years means replacing them because they will break once disturbed. From the car makers stand-point, plastic is cheaper to use, lighter and easier to recycle. From the repair stand-point, it is a conflict of design. Why put so much effort and engineering into the drive train, body, and suspension systems when key plastic pieces jeopardize the entire package?

I still believe BMW manufactures one of the best cars in the world and does so with an eye toward new innovations. A lot of these innovations are what make the cars so special to us. Plastics and composites will certainly be a big part of those innovations for the future. It may be that the plastic embrittlement lessons of the nineties will mean more durability for this decade.

“Lifetime” Isn’t as Long as You Think

By Mike Perkins
BMW CCA/Houston Chapter Technical Advisor
Owner – Bavarian Machine Specialties

After 229,000 miles and 16 years of service and repair work, the Alpine white 5 series was going to be sold to its second owner. I received a call from the lady who owned it informing me of the proceedings so I would know who the new owner was and could therefore continue maintaining the car for him. She also started asking me questions about the purchase of a new BMW. This is not an uncommon situation, one that I see in my business quite often; long term ownership followed by a repeat purchase of another BMW. The questions she was asking me, however, gave me pause for thought concerning the contrast in ownership from the BMW she just sold to the 2001 model she was about to purchase. It is important to understand that this women was not selling the car because it was run down or unreliable. She had made a concerted effort to follow my guidelines for maintenance and repairs for at least 14 of those 16 years (the first two years were spent at the dealer). She was still attached to the car but in her words “it was time”. People want new things now and then, but she had owned the car in the classic sense; you pay good money for a well engineered car, you maintain it and it outlasts 3 other cars. By today’s standards that might seem old fashioned, but in the real world if you run the numbers, it still makes the most economic sense. It’s not easy, however. It requires planning, patience, understanding, and yes, sometimes being inconvenienced.

This brings us to the reason for this article and what I believe is by contrast BMW’s single most important idea behind ownership of a new BMW.

For years, BMW was maligned for building a car that was claimed to be high maintenance. Well, rightfully or not, the new regime took it to heart and has turned 180 degrees. The idea to extend the service requirements to the point that you take the car in as little as possible is a departure from the normal BMW philosophy. A trouble-free, no hassle, pleasant ownership experience for the first several years is what they are after here. The question is: At what price? Although car advertisers, not just BMW, would like you to believe cars should be reliable like an appliance, it just isn’t so! Strap your computerized refrigerator in the bed of a pickup and drive around on Houston roads for a month in our wonderful climate conditions and then tell me it still works. Lets face it, if someone tells you long enough that the car you’re thinking of buying doesn’t need anything done to it for 100,000 miles, sooner or later you are going to buy into it. The low or no maintenance angle sells cars, it’s the latest truth in advertising.

The lady with the 5 series could not fathom the idea that her salesperson said the new car would not need service for “at least 20,000 to 30,000 miles”. When she called me with this claim my answer to her was “that depends”. Without hesitation I told her it depended on how long she was planning on owning the car. If you follow what BMW would like you to do and trade in your car every 3-4 years, then my advice was to do exactly what BMW recommends. At that point the car will become someone else’s problem. On the other hand, I knew her and I knew she would keep it for at least 10 years. This woman is no different than a lot of you reading this article. She will need a more accelerated schedule of maintenance, regardless of the service interval system.

It is obvious that the service recommendations on today’s BMWs are written to appeal to the broader masses of people who do look at cars as appliances and buy into the idea that we live in a throw-away society.

These are the first time BMW buyers who have owned Fords, Toyotas, etc. As BMW expands their market grip, they have to compete on the same level of mindless ownership to survive. How you buy a $60,000 car and consider it a throw away after 4 years is beyond me, but I guess everything is relative. Make no mistake – this new philosophy is about selling cars to a broader range of people who are not maintaining cars for the long haul. Anyone who expects a real return from a highly engineered, highly sensitive car, in fact, the best the automotive world has to offer, should understand the difference.

The idea of a break-in service is long gone. The reality that the basic fluid changes and critical retorque are no longer important should be suspect to everyone. It is interesting to note that the new M5 must receive a break-in service. Are all the other BMWs not deserving of this same service? Ok, I buy the factory’s position that there are no break-in oils used as in the past and that the engine is run-in prior to installation but no matter how fantastic the BMW synthetic oil is (once made by Valvoline – now made by Castrol) no one will convince me that metal parts don’t initially wear. Just building an engine has its share of grit that will be left in the engine and along with microscopic wear particles will cause premature wear. Case in point: I have seen an unusually high amount of problems with scoring on camshafts on new M3’s – several with under 20,000 miles on the clock. Where did this grit come from and what happens if you don’t get it out? You guessed it – rattling timing chains, loud lifters, and low oil pressures. What used to be a guaranteed 250,000 mile engine has a hard time making 100,000 miles. The advice I give is to change your oil with a synthetic brand in one-half of the prescribed service intervals. Do not change from one brand of oil to another, stay with one kind. (The oil that comes in the car is very good at a reasonable price.)

Additionally, the idea that standard transmissions no longer ever need fluid changes is truly alarming. I have no doubt that the “lifetime” fluid will last for the lifetime of the transmission but what will that be, half the life of a transmission that receives regular servicing or just long enough to put the car out of warranty. Pull the plug on any transmission or differential after just 2000 miles and take a hard look at the fluid in the pan with a light. You will see lots of pretty shimmering particles (brass, steel, etc.). These certainly do not add to the life of the bearings.

Automatic transmissions are the same story but with a more expensive downside. The automatic transmissions on most BMW’s now also have a “lifetime fluid and never need servicing”. This is either a great way to sell transmissions or lose the repeat customers who want to own these cars for the long term. Case in point: 94 740il with 78,000 miles came into the shop with a complaint of shifting problems. Now bear in mind this is a 5HP30 transmission which is definitely the most reliable unit that ZF has ever sold to BMW for use. However, the nature of an automatic is to operate under friction (i.e. fiber clutch packs) which will create heat and degrade fluid lubricating properties. As moving parts wear, they create enough aluminum and fiber powder to gunk up valve bodies until the electronic shift valves no longer function precisely as intended. This was the case of the 740il. The transmissions we work on with over 60,000 miles having no past service work are for the most part filthy and in need of basic flushing and filter changes. However, in addition, these transmissions also have a nasty little problem with plastic check balls that shrink and deform due to heat and pressure. When this happens it will cause all kinds of shifting abnormalities or worse. Don’t tell me these transmissions don’t need servicing or I’ll be telling you “well, you have just reached the life of your transmission; that will be $4,500.”

Power steering systems are regularly neglected, especially since BMW makes no provision for routine service. Take the top off any two year old M3 power steering reservoir and instead of nice red ATF (Dextron III) you will see burnt brown fluid. By the 3rd year it will have a grayish tinge to it from all the aluminum powder. By the 4th and 5th years you will develop an occasional cavitation sound from the pump because the filter is clogged. This lack of maintenance could also contribute to a steering rack leak from a side seal or at the very least, worn internal rack bushings.

Coolant and hydraulic changes have also been pushed back which makes no sense given the fact that they are such cheap insurance. Brake fluid is hygroscopic meaning that it readily absorbs moisture when exposed to air. The system does breath through the reservoir cap. Moisture lowers the boiling point of the fluid and can cause brake fade. It has been estimated that in Houston, two year old brake fluid will contain anywhere from 4% to 8% water. This small amount will lower the boiling point by more than 25% to 30% which could cause compromised stopping power when it is needed most. In addition, moisture in the system can cause corrosion in the bores of system components, eventually leading to premature seal wear (i.e. leaking calipers, master cylinders, etc). Most of the ABS related failures that I have encountered can be traced to moisture contamination which leads to corrosion that can make the ABS valves stick. This usually requires expensive repairs that could have been avoided by periodic flushing. Houston has more moisture in the atmosphere than do most places in the country. Because of this, I recommend brake fluid be tested for moisture content at least once a year. Flushing may be wise to do on a yearly basis, especially if the car is exposed to severe driving conditions (i.e. constant freeway stop and go, or track events/auto-crossing).

I also see cars at 40,000 plus miles that according to the service interval system are now due for an Inspection II. Obviously the air and fuel filters are changed as part of this service. However, by this time the air filter is so filthy you can literally bang a small pile of sand and grit out of it. Air and fuel filters are not worth the risk of leaving on the car for this kind of mileage.

Someone on the other side of this might say I’m cynical, maybe because the low maintenance cars mean I will have less to work on. Quite the opposite is true and to this I say: Go ahead and follow the factory maintenance schedule to the letter because the less you do the more the car will eventually break. I am seeing more work, especially large jobs like transmissions and engines than ever before because of the lack of preventative maintenance. My advice is own a car like you’re going to have it for a long time. If you’re looking at buying a car just off lease, check it out carefully. Have every used car checked out even if it is a “certified” car. Remember, “maintained at the dealer” doesn’t necessarily mean what it used to. If you think oil changes at the nearest quick lube shop is maintaining your car, think again. Well intentioned but untrained oil jockeys will guarantee you a false sense of security.

Do not misunderstand my aversion for this lack of reasonable servicing. The technology that has enabled some of this is wonderful. Cars are definitely more reliable and with the advent of 4th and 5th generation electronics BMW’s are easier to repair and infinitely safer to drive. Self-adaptive, self- learning engine management systems with multi-plexing and digital feeds are a good thing. Technology has its rewards but we have to be smart about the reality of what we expect from our BMW’s. It is a shame when BMW engineers a car to last 300,000 miles and then puts it on a service program that gives one the impression they ar only concerned about the warranty period. It is up to you to protect your investment because the alternative is too expensive. As for the lady, she has an appointment for a 1200 mile break-in service next month.

I Could’ve Had a V8

By Mike Perkins
BMW CCA/Houston Chapter Technical Advisor
Owner – Bavarian Machine Specialties

This guy was serious. And even though he was a first time customer, I could see he was very frustrated. “The car idles rough and it sometimes feels like it has a miss. If you can’t fix it, I’m getting rid of it!”

The car in question was a 1995 740il with the V8 motor. From an outward appearance it was a pristine car. He was the original owner and had logged 65,000 miles over the past 6 years. The car appeared to have been cared for both cosmetically and mechanically. So how could the owner be so upset with the car?

Now, in all fairness, I must admit at the beginning of this article that having cut my teeth on BMW engines of the late 60’s and early 70’s, I have always been partial to the outright durability of the 4 and 6 cylinder engines. These well engineered, smooth revving Munich power plants, in one variety or another, have always been a major draw for myself and many others I know. So I was very skeptical when BMW dropped the venerable M30 in-line big six cylinder engine from the US product line in 1993 and replaced it with a V8. What on earth was BMW thinking discarding an engine that had evolved over decades and had proved itself time and again over the last 30 years? The answer of course was simple – market competition. BMW could never achieve the idle quality and smooth torque of a V8 with the older in-line 6 cylinder engines. With growing competition, BMW had to find the right engine befitting the new generation of luxury BMW’s.

Admitting BMW was concerned about competition is something relatively new for me. I believed for decades that BMW’s were built the way Munich wanted and if you didn’t get it, you had no business owning one. But those days have changed, and the all-mighty market share demands fresh ideas and a broader focus. Don’t get me wrong, this isn’t a bad thing, it’s just that there will be teething pains along the way. At least BMW hasn’t stooped to dissuading new buyers by running sleazy TV comparison ads like other car companies. The proof is in the car and if you don’t recognize it, don’t buy it but don’t give me some sales hype! But I digress…

So back to the guy with the 740. After several hours of testing and checks, I arrived at an all too familiar diagnosis. The engine block had damaged cylinder walls and was worn beyond the allowable tolerance. A resulting loss of compression in the affected cylinders was causing an imbalance and an excessively rough idle. This was impossible. The car company that was world renowned for its engine building had a real problem with its initial line of V8’s. After almost 7 years since BMW first released the V8’s, I look back and examine what went wrong and how you, as the consumer, can profit by BMW’s good faith corrections.

For some of you, an article about the ill-fated original line of V8’s might be old news. However, for others of you who own a 5,7, or 8 series car that is almost 6 years old, you might be interested to read on. If you are contemplating buying a second hand 530, 540, 740, or 840, you definitely want to read on.

In late 1993 BMW introduced 2 all aluminum V8 engines. One was a 3.0 liter engine designated as the M60 B30. This engine was only available in the 5 series sedan and touring cars. The other engine was a 4.0 liter designated as the M60 B40, available in the 5, 7 and 8 series. Both engines ran through the 1995 model year when the M60 B30 was dropped and the M60 B40 was upgraded to a 4.4 liter designated as the M62 B44.

Amidst all the rumors about why the V8 engines failed, there is only one true reason. These engine were susceptible to the higher sulfur content found in U.S. gasoline. This sulfur detrimentally affected the cylinder walls of the aluminum block. Although the blocks were cast with a high grade aluminum know as Nikasil (aluminum impregnated with nickel and silicone), the sulfur adversely reacted with the nickel content in the block. This “reaction” took place in the upper portion of the cylinder bores, blemishing the original cylinder wall machining pattern known as “crosshatch”. Without adequate crosshatch, the piston rings would not remain sealed properly and compression would suffer.

Originally, while BMW was investigating the cause and correction of the ill fated V8, several different methods of repair were initiated. The first attempt was an e-prom reprogram to raise the operating temperature of the combustion chamber. In theory, the hotter burn would yield less residual sulfur and therefore lessen the problem. The benefits of this procedure proved to be negligible. The second attempt involved disassembly and repair of the engine by fitting new pistons and rings. After only a limited number of engine repairs, the idea was dismissed as not viable. The third attempted repair required short block replacement entirely. Unfortunately at that time, the real cause of the problem had not been completely diagnosed (as a means of keeping cars on the road). Short blocks were replaced with the identical type of Nikasil block. This is the reason you may see some cars that have had 2 and sometimes 3 replacement engines.

With its reputation tarnished, BMW made a decision to change its engine warranty for all V8 cars from the 4 year/50,000 mile limit to 6 years or 100,000 miles as a good faith gesture. By early 1997, the problem had been fully diagnosed and the solution was fairly simple, albeit expensive. All future V8’s and all replacement short blocks were to be made from the same material used in the V12 engine. This high grade aluminum, called Alusil, is not susceptible to sulfur damage. For those of you whose V8 is a late delivery 95 and you think you have an excessively rough idle, time is running out because the dealer is the only one who can provide you with a free engine. Make an appointment with any dealer and have an idle quality check performed.

However, before running to the dealer with dreams of a new engine for free, it must be clearly understood that there are a host of other possibilities that could cause a rough idle on these V8’s that your own mechanic can verify. It will not be accurate to test for a cylinder leak down problem if you have other engine problems that will mask the suspected cylinder wall problem. To name a few such V8 problems, the number one rough idle contributor is an un-metered air leak at the vacuum diaphragm plate on the back of the intake manifold. Intake manifold to cylinder head profile gaskets can also fail causing a vacuum leak. Injector misfire, valve carboning, low ignition coil output, an valve cover oil leaks into spark plug holes can all be possible idle quality issues. The point here is your engine must be in good otherwise condition before you can claim you need a new short block.

For those of you who are thinking of purchasing a previously owned 1995-1996 5, 6, or 8 series, it is imperative that you find out what kind of block is in the car. Just think, a 90,000 mile 95 540i might really only have 12,000 miles on the motor. Finding out what block is in the car is easy once you know what to look for. All M60 and M62 blocks have casting numbers on the right hand side of the block (passenger side) in front of the starter. It is easiest to put the car in the air but you can certainly crawl under the car with a flashlight. The casting numbers are actually the last 2 digits of the part number and are as follows:

Nikasil M60 B30 – 1 725 970 or 1 741 212
Nikasil M60 B40 – 1 725 963 or 1 742 998
Alusil M60 B30 – 1 745 871
Alusil M60 B40 – 1 745 872
Alusil M62 B44 – 1 745 873

Obviously, Alusil numbers are what you would like to see but it should also go without saying that not every Nikasil block is a bad one. I see some very healthy 100,000 plus mile Nikasil blocks running around. These casting numbers are also helpful to refer to if in the event you need any other internal repairs because for example, parts such as pistons and rings are different and not interchangeable between Nikasil and Alusil blocks.

As for the frustrated 740il owner, he is ecstatic. We took care of a host of engine problems and then assisted him in having his engine block replaced under warranty. Not bad when you consider by the time the car is ten years old, he will have less that 50,000 miles on the motor. The same thing could happen for you but if you miss out because you ignore these numbers, well, remember the old V8 juice commercial – just don’t smack yourself in the forehead too hard.

Houston BMW Parts, Service & Performance