BMW X5 M Oil Separator & Breather Fault
Our client brought in his BMW X5 M because the engine started misfiring and exhaust started spewing excessive white smoke. We conducted diagnostic testing and traced the fault to problems with the oil separator and breather unit in the crankcase. This is commonly referred to as the crankcase vent (CCV). It’s purpose is to stop the oil from getting into the intake ports and combustion chamber.
We replaced the oil separator unit and re-fitted the breather. This successfully resolved the misfire and stopped the exhaust smoke.
What Happens When The CCV Fails?
When the CCV system is working effectively it separates oil from the internal atmosphere of the engine and feeds it back into the sump. Some of the oil vapours will inevitably remain and burn off via combustion or continue to circulate in the engine.
Unfortunately, the CCV systems have become more complex as manufacturers drive to reduce engine emissions. This complexity is increased because the CCV is tied into other systems so any single failure has a knock-on effect. When the CCV system starts going wrong the driver may begin to notice the engine is running roughly, misfiring or stalling completely. There may be a distinct loss of engine performance and a much higher oil consumption. As the situation deteriorates, the exhaust will begin to spew out white smoke.
Other common warning signs to watch out for include a whistling noise, difficulty when trying to open the oil cap and a white/yellow coating under the oil reservoir cap.
If no remedial action is taken, the engine’s lifespan will be shortened.
Get hold of us immediately if you notice any of these symptoms.