BMW PCV Valve Diaphragm

Choosing A PCV Diaphragm Repair Kit

A PCV diaphragm repair kit is intended for the crankcase ventilation arrangement on a specified engine. The A-Premium selection includes valve-cover repair kits for selected BMW and Mini applications; one Mini product lists a specific engine-code requirement.

Identify the engine and the ventilation component being serviced before ordering. A diaphragm kit, a valve-cover cap and a complete valve cover can have different repair scopes and package contents.

How A PCV Diaphragm Controls Crankcase Pressure

In a pressure-controlled crankcase ventilation system, the valve regulates airflow and pressure as engine conditions change. BMW describes spring-and-diaphragm pressure-control valves in its crankcase ventilation systems, although the valve layout varies by engine.

The valve works with the cover and ventilation passages. A damaged housing or blocked crankcase breather hose needs its own inspection; replacing a diaphragm does not correct every problem in the system.

Diagnosing Crankcase Ventilation Problems

Rough idle, oil leakage or unusual crankcase pressure can have more than one cause. Inspect the ventilation system and use the diagnostic procedure for the engine before deciding whether the diaphragm, another ventilation component or the cover is at fault.

Frequently Asked Questions (FAQ)