BMW Common Repairs

Import Performance Wilmington NC

BMW Automobiles are luxury performance machines.  The maintenance on these vehicles is crucial. 

Cooling system failures

In 2006 BMW switched to electric water pumps on most models.  The electric water pumps will typically begin to fail at around 90,000 miles.  The first indication will be a check engine light illuminated in the instrument cluster.  The engine computer will monitor the water pump operation and thermostat operation to track the engine cooling system performance and will pick up on a fault before it becomes catastrophic.  It is important to take the vehicle in as soon as possible to avoid possible further damage due to engine overheating.

The electronic thermostat should be replaced when the electric water pump is replaced along with a cooling system flush. 

It is critically important to use only OE BMW antifreeze in the cooling system to ensure proper operation and longevity of new components.  BMW antifreeze is blue in color and formulated specifically for the BMW cooling system.

Oil leaks

Unfortunately oil leaks are going to occur on your BMW as it accrues miles.  The most common leaks occur because rubber seals and gaskets over time and use become hard and brittle.  When we document oil leaks we classify them as follows.

 -Seep: Wetness or dampness, not dripping – should be noted only

-Leak: Trail or liquid on surface or in tray, not dripping on ground – Repair to avoid further damage

-Drip: Liquid dripping on the ground Repair Immediately

-Severe leak: Liquid dripping out and creating a puddle Dangerous

When oil is actively leaking (classified as leak or above) as it leaks down the engine is can hit the exhaust system.  When oil touches the hot exhaust system it will burn causing an unpleasant smell that is often introduced into the cabin of the vehicle through the intake of the climate system under the hood.  Oil can also come into contact with rubber hoses, belts, rubber engine mounts and suspension bushings.  When oil contacts rubber components it begins to penetrate the rubber causing it to swell and weaken.  To avoid costly repairs larger oil leaks should be addressed quickly and the surrounding areas should be cleaned thoroughly. 

Typically if you are smelling oil burning inside your vehicle the culprit is a valve cover gasket leak.  As the leak gets worse it can make its way down the exhaust system to the catalytic converter.  The catalytic converter does get hot enough through normal operation to ignite the leaking oil and start a fire in the engine compartment.  While this is not common the best practice is if you are smelling oil burning in your vehicle it should be brought in to be evaluated and corrected quickly. 

Often when there is an oil leak there are no obvious signs to you.  All newer BMW’s have covers under the engine compartment and the transmission tunnel.  Oil will leak from lower spots on the engine and get caught by the trays before hitting the ground.  When your vehicle is serviced at Import Performance we perform a thorough check over of your vehicle every time.  This includes inspecting the undercarriage and removing the under trays.

Engine breather system failures

When an engine is running a small amount of pressure builds inside the crankcase due to blow-by.  Blow-by is leakage of combustion gases between a piston and the cylinder wall into the crankcase in an internal combustion engine.

Before emissions regulations this would be vented to the atmosphere through a simple one way check valve called a PCV valve.  In modern vehicles this needs to be dealt with differently.  BMW uses an oil separator that is connected to the crankcase and the intake manifold through a series of breather hoses.  This comprises the engine breather system or crankcase ventilation system.  When the oil separator fails or a breather hose leaks it can cause an intake leak through the crankcase causing a lean condition and check engine light illumination. 
In addition this type of failure will cause a vacuum to be pulled on the crankcase and can cause excessive oil consumption and smoking out of the tail pipe.

Another way the oil separator can fail is it can become clogged with oil sludge and deposits.  This type of failure is a result of poor oil quality or infrequent oil changes.  When the oil separator is
clogged the engine crankcase is unable to vent the blow-by.  This causes a buildup of pressure in the engine and in turn oil will begin to leak from various seals and gaskets.  Often if your vehicle has multiple oil leaks on the engine the oil separator is the underlying cause. 

Failures in mechanical variable valve timing systems due oil quality.

The modern BMW engine utilizes numerous systems to vary valve timing, valve lift, and intake manifold capacity.  These systems need to be operating optimally to maintain the performance you have come to expect out of your BMW. 

Often what happens on a BMW engine with higher miles is the oil passages that control these systems will become clogged with deposits and cause incorrect valve timing.  This will result in a rough idle, check engine light, poor fuel economy and a lack of power. 

To avoid this it is important to use high quality fully synthetic motor oil and have it changed every 7,000 to 10,000 miles or annually whichever occurs first.

Some newer BMW cars and trucks will have manufacturer service intervals of up to 15,000 miles.  This is often the reason for most of the common failures we have seen.  Oil quality is paramount to the longevity and performance of your vehicle.  At import performance we recommend an oil change with BG additives every 7,000 to 10,000 miles using synthetic oil to minimize repair costs down the line.

Ignition coil failures due to worn spark plugs

If your check engine light is flashing while you are driving the vehicle should be stopped immediately and towed in for service.  When the check engine light flashes while the engine is running it means there is a malfunction severe enough to cause damage to the catalytic converters and other emissions systems and components.

The most common cause for a check engine light blinking while the engine is running on a BMW is failed ignition coils.  Modern BMW engines use direct Coil On Plug ignition systems.  The computer triggers the coils to fire sequentially and can optimize ignition timing in all running conditions. 

When spark plugs wear down the distance between the ground electrode and the center electrode increases.  This increased “Gap” in turn increases the resistance of the plug as it fires.  When the coil fires the worn plug more current is drawn from the coil causing it to fail prematurely. 

Typically a BMW will call for spark plug replacement every 100,000 miles under normal use.  Often waiting until 100,000 miles will result in ignition coil failure.  The reason for this is the term normal use rarely applies to anyone.  Below is a brief explanation.

Notes on “Severe Service” 

The maintenance intervals that are listed under Normal Service are designed by the vehicle manufacturer to meet the needs of the “Average” motorist.

Since maintenance intervals are affected by climate and operating conditions, customers who operate their vehicles under more arduous conditions, or who’s driving habits are markedly different from the “Average” motorist should have a more personalized service program developed for them. This will ensure the continued safe and reliable operation of their vehicle.

Because this manufacturer does not specify a Severe Service Interval, the determination of the proper maintenance interval should be left to the good judgement of the vehicle owner and the advice of an authorized service center.

Conditions that will change the frequency and composition of Normal

  • Operating in dusty, wet or muddy terrain
  • Frequent driving in dense city stop and go traffic
  • Repeated short trip operation without sufficient engine warm up
  • Ambient temperature extremes
  • Operating in mountainous/high altitude areas
  • Trailer towing

NOTE : Low mileage vehicles should be maintained at least once a year.

Typically we see a need for spark plug replacement around every 80,000 miles on BMWs in our region.  When we recommend spark plug replacement we base it off of a visual inspection of the spark plug after it is removed from the engine unless otherwise noted.

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