Our latest featured repair is Crankcase Vent Valve Replacement on a 2006 BMW X3, brought to us by a client from Squamish, BC.
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.
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. http://en.wikipedia.org/wiki/Crankcase_ventilation_system
For more on the BMW X3 click here. http://en.wikipedia.org/wiki/BMW_X3