August 6

2006 BMW X3- Crankcase Vent Valve Replacement

Auto Repair, BMW


Our latest featured repair is Crankcase Vent Valve Replacement on a 2006 BMW X3, brought to us by a client from Squamish, BC.

2006 BMW X3

All engines have a ventilation system to deal with the pressure build up that occurs in the crankcase. Combustion gases also escape the piston rings: these contain particularly noxious pollutants that are extremely damaging to the atmosphere.

Up until the 1960’s most engine’s dealt with the crankcase gases with a simple road draft tube. This prevented pressure build up but vented the harsh pollutants to the air. Crankcase ventilation systems were developed whereby the blow-by gases were sucked back into the intake system and reburned.

Crankcase ventilation system systems vary from a very simple arrangement of two vacuum hoses and a PCV (positive crankcase ventilation) valve to more complex arrangements such as those found on this BMW.

Components of the BMW X3 crankcase breather system are common to most BMW 6 cylinder engines. At the heart of the system is the crankcase vent valve. From there a series of hoses connects to various engine parts: the intake manifold, the valve cover and the oil dipstick tube.

Components of the BMW crankcase ventilation system. The Blue arrow points to the Crankcase Vent Valve. The green arrow points to a break in the hose which runs to the oil dipstick tube. This hose was rotted out from the combustion gases. Other components of the system are the hoses and plastic manifold which clips into the intake manifold. Our featured vehicle was originally from Ontario and comes equipped with the cold weather style of crankcase ventilation. This includes insulating covers over all components to retain heat.

When these components fail several concerns will occur including billowing clouds of blue smoke on start up, excessive oil consumption and a rough idle. Our featured X3 was suffering from the first two: oil was needing to be added to the engine every couple of weeks and some engine start ups were accompanied by an embarrassing cloud of smoke.

Engine oil burning is always a concern as it can involve expensive internal engine repairs, fortunately on BMW’s with 6 cylinder engines the cause is almost always the crankcase vent valve.

For more information on crankcase ventilation system click here.

For more on the BMW X3 click here.


About the author 

Bernie Pawlik

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