Crankcase Vent Valve - E36, E39, Z3

The crankcase vent valve (CVV) holds and releases oil vapors that build up in the engine. It's the same type of system previously known as a PCV valve and the same deficiencies exist. Over time, the CVV will become saturated and clogged with oil. When this happens, the oil-rich vapors from the engine will back up into the intake tract and eventually into the combustion chamber. The oil added to the gasoline/air mix will cause misfires, carbon deposits, rough running, and blue smoke out the tailpipe. Replacing the CVV every 70,000 miles will ensure the correct and clean ventilation of oil vapor.

Replacement of the CVV can be done without removing the intake manifold. But replacing it during an M50 Manifold upgrade is the perfect time.

This is a Genuine BMW crankcase vent and sealing grommet -
11151703484 - crankcase vent valve
13411733217 - sealing grommet

This item fits the following BMWs:
1996-1999 E36 BMW 323is 323ic 328i 328is 328ic M3
1997-1998 E39 BMW 528i
1997-1998 Z3 BMW Z3 2.8
1998-2000 Z3 BMW Z3 M Roadster M Coupe