Service bulletin 110308

A bulletin is a manufacturer's communication to its dealers, as NHTSA indexes it. The summary is NHTSA's. The document is the manufacturer's: read it at NHTSA. A bulletin is not a recall, and listing a model year does not mean every vehicle of it is concerned.

NHTSA's summary

Crankcase Ventilation System Diagnosis and Measurement. INFORMATION All current BMW engines incorporate a pressure-controlled crankcase ventilation system. The crankcase ventilation systems use various different crankcase ventilation valves, depending on the engine type. Although the valves all look different, they function similarly, using a spring and diaphragm assembly to control the crankcase pressure. A properly functioning pressure control valve is designed to maintain a slight vacuum (under-pressure) in the crankcase, which assures reliable crankcase venting during all engine operating conditions. Some of the causes and results of a malfunctioning crankcase ventilation system are listed below. Causes of Excessive Overpressure (Pressure) * Internal engine damage/wear * Obstruction in the crankcase ventilation system * Defective pressure control valve(s) Results of Excessive Overpressure * Damage to the engine oil seals * Increased engine oil consumption (can be misdiagnosed as a defective turbocharger) * Excessive engine oil in the intake system * Excessive engine oil in the charged intake tubes or the intercooler on turbocharged engines (can be misdiagnosed as a defective turbocharger) * Engine oil dip stick is dislodged from the guide tube (if equipped) Cause of Excessive Under-pressure (Vacuum) * Defective pressure control valve Results of Excessive Under-pressure * Damage to the engine oil seals * Increased engine oil consumption * Excessive engine oil in the intake system * Rough engine idling or engine misfire * Whistling or howling noise from the engine (can be misdiagnosed as a defective turbocharger) * Increased mixture adaptation values N63, N63T, N74, S63 and S63T Equipped Vehicles The crankcase ventilation system utilized in these engines cannot be measured with consistency because the system does not incorporate a regulating valve (spring with diaphragm). The crankcase pressure is regulated by an orifice in the crankcase ventilation tubes, and the

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Components

Engine

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