I have an 2000 A6, 2.7 Biturbo. Interesting thing happened today.

It was parked outside, about -9C and I started it up. It started well, seemed like there might have been an excessive amount of white exhaust color, but nothing too bad. I let it warm up for 5-10 minutes before I drove away. Then in the review mirror I noticed that the excessive exhaust was still there, and it was tinged with blue. I have had a blown turbo before, years ago on an Audi 5000, so this looked like classic blown turbo.Almost no smoke until you let off the gas and then there is a massive amount of blue smoke.By the lookof the smoke and quantity of it, I thought, "Ok, one or both turbos are shot."

I went to a garage/performance shop and told them I need a quote to replace the turbos. (Car has 210 000 km, so the turbos are getting older.) They told me they will get back to me next week as they were just closing. I continue to my next errand and the car started to reach normal operating temps. When that happened, all traces of smoke and excessive exhaust disappeared, and its normal again.

I have never heard of a turbo doing this. I guess its possible the turbos aren't the issue, and that it might have been caused by oil in the exhaust. Not sure how oil would get in the exhaust, and the amount of blue would seem to indicate that it was more than valve seals. The cars performance seems normal.

Any thoughts?

As well, if I need to replace the turbos, what do you recommend? Rebuild both? replace them with something of more performance? Its a 7 year old car, I like it, but its unlikely I willl keep it more than another 2-3 years so I don't want to spend a tonne of cash on aftermarket turbos.

 

-9C could be the reason

 

I have never noticed this before when its been -20C and I have started it up. Its not 'supposed' to do that obviously, -9C is well within normal operating parameters for this car.

I still need to check the oil, its possible it could be slightly overfull and that the low temperature caused some strange issue with excessive oil. I honestly don't think its overfull, but I still need to verify it. Even still, I don't see how overfull oil would cause this issue and get into the intake/turbos/exhaust.

 

the temps are low enough to see smoke at -9C but would dissipate when the engine was warmed up, as for oil in the system it could be a bad PCV and small amounts of oil could have got past it into the breather pipe and that's not uncommon

 

At this point, I am just going to monitor it, if it gets worse, or repeats, then I will replace them. I am also going to do some aftermarket turbo research and see what my options are.

 

Freaky coincidence, but mine did nearly the same thing yesterday. No joke. Daytime temp was around 20F. I drove about 3/4 mile to post office, turned it off for about 10 mins to get mail. Started driving again, and as I got into the throttle to avoid being overtaken by some young punk in a pickup, I noticed things looked hazy behind. By the time I drove the three miles home, an embarising amount of white smoke was pluming behind me. Definitely worse whenever I used the throttle. Performance seemed alright. When I parked in my garage, I notice smoke appeared to be coming out of both pipes. It smelled pretty bad, and I though it was familiar of antifreeze and oil smoke combined. I first suspected bad fuel, but it has been more than 30 miles since my last fill-up, and I haven't noticed any trouble till now. Head gasket would likely lead to smoke from one side of the exhaust, not both. After looking in my repair manual, I am suspicious of a turbo gone bad as they are supplied by both oil and coolant, and if things went awry, this could lead to leaks into both intake and exhaust. I've only owned the car about 6 months. Had 62k mi when I bought it, and now has around 68k mi. Has alway worked great up till now.

Let me know if you discover the source of your trouble, as mine may be the same. Nearest dealer is 100 mi away, and I'm nervous to drive more than a few miles at this point.

 

Have done some more research on this issue, there is some posting on Audi-World that talk about a blocked breather line causing this. Could be excess pressure in the crank case. I think what they are referring to is PCV valve related. It's likely that the colder temperatures cause either a component to fail, or there is moisture in the system that causes a block that melts out or causes a valve to not open properly. I will continue to explore. If anyone else has knowledge in this issue and can add anything, please do. It was -9 today and it was fine.

 

What is the name the PCV valve is known officially? Bentley shows no PCV valve (at least I’m not able to find one). Any part #? Location?

 

Did a quick search for PCV valve from online parts suppliers. None listed for 2.7T (03-04) or all.

 

Well, they are pretty much always called a PCV valve, but alot of people are referring to it as a Breather Line, or the PCV value is connected to the Breather line. A quick hunt on Drive line yielded a part. #... Not sure if this is what they are referring to. At this point its not done it again so I have not investigated it further. The temperature has not been as cold etiher for the last 1-2 days. If you look on Audi World, you can likely find a reference if you search for 'Breather line".

http://catalog.drivewire.com/drivewi...part=PCV+Valve