BMW crankcase vent valves fail more often this time of year and we see more of these types of problems as the weather gets colder. The BMW crankcase ventilation valve is also known as the oil separator, CCV, or PCV valve. According to Wikipedia, "A crankcase ventilation system is a one way passage for gases to escape in a controlled manner from the crankcase of an internal combustion engine. This is necessary because internal combustion inevitably involves a small but continual amount of blow-by, which occurs when some of the gases from the combustion leak past the piston rings (that is, blow by them) to end up inside the crankcase, causing pressure to build up in the crank case. For control of the pressure inside it, a PCV is used to vent the crank case."
Condensation can build up inside the crankcase, which can then freeze as the temperature drops. This can cause the BMW crankcase vent valve to rupture. Symptoms of a bad BMW CCV are: white smoke coming out of the exhaust, excessive oil consumption (burning oil), engine running rough and misfiring. Failure of the BMW crankcase vent valve creates a vacuum from air being sucked through the rear main seal. This can cause an engine noise that sounds like a whistling or sucking sound. As demonstrated by AskTheCarExperts, a simple test to see if you have high crankcase pressure, is to try to remove the oil cap while the engine is running. If there is high suction holding the cap down, this is a good indication that the BMW crankcase vent valve has failed.
For all of your BMW repair and service needs, contact the professionals at DJ Foreign Auto Care. We can diagnose and replace your BMW crankcase vent valve! We are located at: 2626 University Ave NE, Minneapolis, MN 55418. Call today to get on the schedule: 612-588-3305.