myles
03-10-2008, 04:28 AM
Thought I should leave a post here on my fix for a problem that I struck on my E36 318is. The car started making hissing and whistling noises and then started running rough. The whistling and rough running were intermittent but the hissing was consistant. The problem was the crankcase ventilation valve had broken internally. It is designed to regulate the stength of the vacuum in the crankcase. The intake has a much stronger vacuum than the crankcase is meant to have, but the failed cvv was not reducing the vacuum in the crankcase and it was sucking air in somewhere when the engine warmed up and made the whistling noise. The hissing noise was coming from the small vent on top of the cvv. The rough running was caused by the unmetered air entering the intake via the crankcase. The extra vacuum also caused the crankcase vent hose that runs from the valve cover to the cvv, to colapse and split wide open. The other symptom that I noticed was that when the engine was running the oil filler cap was sucked closed really tight and had to be pried off.
After replacing the cvv and the hose the problem is fixed. The oil filler cap is still held down slightly by the crankcase vacuum, but is only just noticable compared with the vacuum with faulty cvv. The old cvv had dropped some of its inards into the intake manifold but were easily removed.
The cvv is fitted to all M42, M43 and M44 engines in E36, E46 and E34 cars. The new cvv is a slight redesign on the old part with a new part number.
After replacing the cvv and the hose the problem is fixed. The oil filler cap is still held down slightly by the crankcase vacuum, but is only just noticable compared with the vacuum with faulty cvv. The old cvv had dropped some of its inards into the intake manifold but were easily removed.
The cvv is fitted to all M42, M43 and M44 engines in E36, E46 and E34 cars. The new cvv is a slight redesign on the old part with a new part number.