My buddy has a 2009 JCW that will billow white smoke after idling for ~10+ minutes. Once it blows the smoke it goes away quickly until you idle again for a prolonged amount of time. It doesn't smell like coolant is the peculiar thing, and I am not sure how to explain what it smells like, but it a foul smell.

There's no coolant in the oil, he is going to do a leak down before long, figured I would check here for other ideas as well.
Thanks.

 

A couple of thoughts. First, head gasket. Leak down test a good idea, at least a compression test. Other thought is perhaps water in the fuel?

 

It has done it for a few weeks now and the car runs fine, so I don't believe water in the fuel or else it would run horribly I'd assume. I don't suspect the head gasket as there isn't any coolant in the oil and it doesn't smoke constantly.

I personally suspect the turbo may be the issue.

 

I'm having the same issue. I'm guessing it's going to be valve seals, could be turbo though. I'm going to try and diagnose my problem this weekend.

 

Most likely valve seals or guides.

 

Same thing happens to mine but only when A/C is on. Let me know what fixes it.

 

 

Possibly valve seals---they were causing the smoke from my exhaust when accelerating away from a stop light. Switched to Mobil 1 high mileage motor oil and used half a bottle of Barr's Stop Leak mixed in the oil, no more smoke.

 

I had this too right before my thermostat housing was replaced. Afterward, everything was fine. It's been 2 years, everything seems ok. (knock on wood)

 

Was this issue resolved, my 2011 countryman s is doing the same thing, after idle for about 10 minutes white smoke, awful smell (not sweet), then after accelerating it goes away until I sit at idle for about 10 minutes again

 

Mine is still running well, no smoke 2 years after replacing the T-housing.

 

Is the car using coolant? Any sign of exhaust gasses in the cooling system?

 

Just brought it to the dealer, they said it smells a little sweet, so they are going to figure out where the coolant it entering from. But I dont think it's a bad leak, cause it's not smoking all the time. Coolant looked and smelled fine to me, but I'm not a mechanic. Oil was changed the other week and it looked normal, and didnt have a funky smell either.
car is still under extended warenty so I'll keep posted on what the issue was.

 

Another good way to check is to pull the spark plugs and inspect. If you're getting coolant into a cylinder, it will tend to steam-clean it; the porcelain inside the plug will be bright white and the electrode will be super clean.

 

Very good information, thank you.