I am new to this forum, and a first time owner of a Porsche. I purchased a 2002 911 C4S and with 112,000Kms on it. Everything seemed fine with the car but I have noticed that if the car sits for longer then 2-3 hours it has a cloud of white/blue smoke come out of the exhauts at start, for approximetly 5 seconds. I am extremely concerned that this could be a cylinder head, or head gasket. Does anyone know what it could be, or have they had a similar condition and ti turned out being something different then the two possabilities mentioned above?

Your help would be greatly appreciated as I am loosing sleep over this issue?

 

Welcome to the forum, I personally have not had that issue but I know some others that have. Hopefully you can find an answer.

 

Thanks! I have owned a 1999 BMW and now own a 2002 A4, I have had very good experience with my previous cars in terms of reliability and put allot of Kms on them year after year. That is the main reason I decided on buying a summer car rather then another decent daily driver.

This is definetly a discouraging first few days with the car, I really hope it's nothing major.

Any help or leads would be great!

Any idea how much a head gasket repair would cost at a decent private shop?

 

Ok, from reading the forums it sounds like it is a common issue somewhat. So I will elaborate on the conditions.

The smoke is actually light grey is with some bluish in it. So I would assume it's oil burning. I find it happens when I beat on the car and let it sit for 2-3 hrs. I just went out to start it up after beating on it and it had some smoke but not a huge amount. I will go back out after 6.5 hours to see if it is still present as hopefully the oil was burnt off the last time i started it and did not drive it.

Let me your thoughts guys, should I be concerned or does this sounds like typical symptoms of a used C4s.

Thanks in advance!

 

Sounds like a possible AOS going out... Is the oil cap hard to remove with the engine on?
AOS = Air Oil Separator

 

if it only occurs after really hard driving and hard "S" type corners with left to right switch backs it's caused by oil getting by the piston rings and burning off, it's normal for a flat 6 engine to do.....
if it's occurring all the time it's an issue. I had it happen the first time at auto cross sure as hell freaked me out!

 

Thanks for the feedback! I'm not sure what you would classify as hard driving. Lastnight I drove it hard up to 6500rpms in first, second and third and with in 2 mon of that had the car in the garage turned off. And this morning a bunch of smoke.
I would assume that would be expected?

Then this morning I drove 30min to work, them opened it up once in 3rd and 5th to about 6k-6.5k rpm and pulled into work about 5 min after that and when I started the car after 2.5hrs there was some smoke but more then your average car, but not a huge cloud. Would that also be normal for the driving description?

Also, I will check on the oil cap to see if it's hard to remove when the engine is running.

Any idea how much am AOS costs? Just part alone?

Once again, thanks for all the feedback, I haven't been part of a forum since the teen years of driving done up civic's, I look forward to lots of activity on here!

 

hmm, thats not driving it hard.... I drive mine to redline almost every time i take it out, and never had that issue, only had the cloud of smoke when cornering really hard in autocross(car side ways then turn and get it sideways the other way...), seems like you do have an issue of some sort...possibly AOS

 

Hmm....that sounds concerning. It's hard not to drive the car hard that's.

Does anyone have the issue as me where it doesn't need much to hard driving to have smoke at start?

Has anyone replaced the AOS and found it has resolved the issue?

 

Sounds like your AOS is going bad especially at that mileage but can happen at any milage. Part wise its about $100 but the labor will cost a ton unless you work on your own cars. Not too bad of a job (on a boxster) a 996 is a bit different since the engines are 180 degrees differently placed but can be done. You should check over at rennlist.org there is a good write up on how to do it... Good luck..

 

Another vote for AOS here. Fortunately, it's a cheap fix. I hope that's it.

 

+1 on the AOS...happens to mine not long ago...after a hard run, the next day while driving..white smoke starts coming out...I parked it & restart the car again & it still smokes....took it to the shop & replace the AOS...no more smoke after that...cost an arm & a leg tho..

 

Thanks for the feedback guys! Took it out for a drive lastnight and no smoke, prior to parking I drove it for about 40min not hard. Looks like it is tied to my driving habits I'm feeingl much better now!

I will definetly check out the diy site might be a good winter project while the car is put away.

 

Pretty sure it is the AOS (air oil separator)

 

your car has around 60K miles on it. AOS is not likely. I would check to see if your oil level is too high. Your oil level should be around the 1/2 mark on the dip stick or it will smoke too much on start up after hard driving. Plenty of discussions on it on Rennlist.