Porsche Enthusiasts Club Forum

Help!!!!!
Have 52 plate 911 C4, which smokes very heavily on start up from cold, but clears completely after 2 or 3 minutes of normal driving. It's actually quite embarrasing. Anyone know what this might be?

What colour is the smoke?

Sounds like an air oil separator gone west.

Yep, I'm having the same issue. Nothing for a couple of weeks, then the next 4 start ups I fill the street with smoke. It clears after a minute or two. But if the AOS has gone, wouldn't it smoke more often, and also when running?

Dave

AOS failure tends to cause smoke on startup. The cause is oil trickling down the intake while the car is stood, which pools and is burned on startup.

A quick test is to remove the oil filler cap while the engine has been running for a few moments, if it feels more difficult to remove with the engine running, than when it is not, (caused by a severe vacuum pulling on the cap) then the AOS has failed.

We use a manometer with an oil filler cap connected to one end to test cars in the workshop.

Yep, thats a kind of home brew version of what we use.

Might be a bit too much effort for just the one car, but for a group of friends it might be worth putting together and sharing.