View Single Post
Old 12-16-2007, 07:53 PM   #61
Registered User
Join Date: Nov 2007
Location: Raleigh, NC
Posts: 1,295
My Ride: 528i 06/00
Originally Posted by GWU_Greek View Post

I already ordered the vanos seal repair kit because I used to have this problem ALL winter last year. However, I recently changed my oil seperator and noticed that the cold start issue never came back eventhough the temperature around here are in the lows 20s in the morning.

I am going to replace the vanos seal nevertheless but I have a question. Based on my research I found that a leaking or bad oil seperator (aka crankcase ventilator) will cause sludge to built up. the oil seperator removes moisture from your crankcase. if it is defective then air and moisture will form and propagate the formation of sludge in our m54/m52TU engines. Beside, the sludge problem a bad oil seperator will cause a vacum leak and thus will cause an abnormal start up hesitation.

Is this true?
I seriously doubt a new CVV valve will resolve the vanos cold engine start idle problems. I have a new CVV with new hoses. Iíve performed lots of seals testing. When I have old seals (pistons) I get the idle problems. When I have new seals I donít have the idle problems.

Fuel injector cleaner has been known to temporarily solve the idle problems. Buna O-rings are susceptible to many harsh chemicals. These chemicals will cause the O-rings to swell. This swelling will initially act beneficially. The vanos Buna O-rings have significant compression set, flat top and bottom surfaces, and shrinkage. The swelling will increase their size and cause them to provide better support and seal to the Teflon seals.
But this is all temporary. The presence of the fuel injector cleaner will diminish, and the O-rings will lose their swell. The injector cleaner will have acted determinately on the O-rings. It will have dissolved from them the components that give them their elasticity. Thus although there is temporary improvement, the end result will be the hastening of the O-ring demise.

The DME utilizes the vanos to help heat up the cats faster on cold engine starts. It is at this time that the idle problems occur due to the failing vanos.
The DME does not perform this vanos maneuver immediately at startup. It waits until the engine warms sufficiently to handle the vanos (timing) maneuvers. Thus the colder the temperature, the colder the engine, and the longer the engine needs to warm up before the DME performs the vanos maneuvers.
It might be that you are not waiting long enough to allow the engine to warm up to the point where the vanos is used to heat up the cats. When the car is driven the idle problems donít occur, unless the car soon comes to a stop and idles again.
Rajaie is offline   Reply With Quote