Smoking Carerra4.

[RickyLeeds]

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?

[Sean Smallman]

What colour is the smoke?

[jmgarage]

Sounds like an air oil separator gone west.

[daveyb]

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

[jmgarage]

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.

[thirteeneast]

http://www.renntech.org/forums/topic/39 ... a-bad-aos/

[jmgarage]

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.