2.0T Burning Oil Smell

[yakev724]

Cross-posting from the Q5 subforum to get some more exposure.

I have a 2011 Q5 2.0T with about 63k, had pistons/rings done (along with new chain + tensioner) at 53k.

On three separate occasions in the past week, I've smelled burning oil in the cabin and in the engine bay from the pass side. On all occasions I was pushing the car mildly (4-4.5k), so I get the sense that turbo pressure has something to do with it. The smell lasted for only a few minutes each time (though each time it happened, I backed off).

Upon close inspection, I couldn't find anything obvious. Some spray on the turbo manifold (pictured below) but after comparing photos between the 2nd and 3rd times, there isn't any additional spray to account for the smell. I inspected the timing chain covers and front crank seal/bellhousing areas and they're dry. Only oil residue I saw was on the black plastic shielding of a line between the turbo manifold and block - I think this is the turbo coolant line.

Anyone experience something similar?

[van462]

Take a close look at the top of the turbo inlet at the aluminum accordion pipe that comes from the PCV. When in boost it is carrying oil vapor to the turbo inlet vs the intake manifold. Its fairly thin.

[jfo]

Take a close look at the top of the turbo inlet at the aluminum accordion pipe that comes from the PCV. When in boost it is carrying oil vapor to the turbo inlet vs the intake manifold. Its fairly thin.

Try to check the spot where this pipe exits the PCV plate. It's hard to see with the coil pack for that cylinder in place, but there is an O ring seal that may be leaking vapour. It's difficult to say what caused those splatter marks, given the broad coverage pattern?

[yakev724]

Good possibility - I inspected the pipe but couldn't find an issue.

When I had my pistons/rings done, they replaced the PCV (*AE) and flashed the ECU. I've heard this new PCV operates under higher pressure so I could see how the gasket to the turbo inlet could give out, that would make a lot of sense. If it comes back from the dealer without them finding anything wrong, I'll remove + reinstall this pipe with a new gasket and try to test for pressure while its off.

Is there a part no. for the o-rings?

[van462]

If the PCV is operating correctly the higher pressure is actually higher vacuum. It should be trying to suck air in vs blow oil out. If the PCV fails boost pressure leaks from the intake manifold into the block and may pressurize that pipe. Check that you can remove the oil fill cap with the engine running. It should have a slight suction. If it can't be removed then you have an issue.

[jfo]

If the PCV is operating correctly the higher pressure is actually higher vacuum. It should be trying to suck air in vs blow oil out. If the PCV fails boost pressure leaks from the intake manifold into the block and may pressurize that pipe. Check that you can remove the oil fill cap with the engine running. It should have a slight suction. If it can't be removed then you have an issue.

Isn't the direction of vapour flow in that pipe from the PCV to the turbo when under boost? In my case with a catch can, the flow is from the PCV through the can, and then back through the breather plate to that turbo pipe.

[van462]

Yes the flow is from is always from the crankcase to the one of the intakes. When not in boost the PCV directs to the intake manifold as it is in vacuum. This is the shortest route to burning these vapors off. When boost is present in the intake manifold the PCV switches the path to preturbo (breather plate always routes this way but adds an extra filtration) as this area is always in a vacuum and never in boost. Sending oil vapor thru the turbo compressor and intercooler isn't the best choice but it the only option to keep it an enclosed system. If the PCV malfuntions then pressurized air goes from the intake manifold and into the PCV and crankcase (and then possible back preturbo). The crankcase is designed to be held in vacuum. This can lead to things that have large surface area like the valve cover to flex and lose its seal. The B7 with the plastic valve covers were known to crack covers due to this.

[yakev724]

Interesting.

I'll test both at idle and boost (in neutral) to confirm I'm getting vacuum in the crankcase. Maybe I'll try using the dipstick tube first. Don't think its the PCV since that was replaced not very long ago as part of stage 1 of the oil consumption fix.

[yakev724]

With my engine running both at idle condition and under boost (~4k), there's a pretty signicant vacuum which makes removing the oil cap difficult. With the oil cap removed at idle, the engine shakes and hesitates significantly (see video below). At higher revs I guess the stroke cycle balances it out and it seems ok.

I've read that the stg. 1 oil consumption fix involved replacing the PCV with a higher-pressure revision (along with ecu flash). If this behavior at idle is normal, I guess I'll just inspect the PCV, lines to the IM and turbo, and the IM (flappers?) for normal operation in the next couple weeks. As a last-ditch effort might try running the pre-oil consumption revision (*AC) to see if that one resolves the issue.

Car was at the dealer today and they didn't find anything abnormal. Have had burning oil smell in the cabin on 4 occasions now over the past 2.5 weeks.

[atxdjlucas]

was this issue ever resolved? I seem to have the same issue.

[BradyBoi55]

was this issue ever resolved? I seem to have the same issue.

I remember looking through this thread about 6 months ago. I ended up fixing my problem of oil burning smell under hard acceleration up/at highway speeds. It ended up being a leaky valve cover gasket. If you decide to tackle this yourself be careful. Our valve cover acts as a cam bridge.(It holds the cams in place) and as soon as you remove the cover the cams want to come up. The cover also has to be torqued perfectly so the cams dont rub on the cover. You will also have to disconnect the line to the HPFP and half remove the vacuum pump on the back of the engine. I had to remove the front bumper and front core just to get to the upper timing chain cover to remove it so i could get the cover off. The best part is there isnt even a gasket. It is a silicone you have to use. But before that you have to scrape off all of the old dried up silicone and try your hardest not to get any into the engine. Here is a video of a 2.0t with the valve cover gasket being replaced.

https://www.youtube.com/watch?v=eHCn...el=NCSProjects

[Theiceman]

Not to mention the sealent is Uber expensive
This job is not for a rookie by any means.
Just be aware

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[BradyBoi55]

you don't need to use audi specific sealant. Their sealant is $100+. Instead use Ultra Grey RTV and let it dry for 24 hours. Many auto manufactures use this stuff and just relabel it. Such as honda and ford. It just as good as the audi stuff maybe even better. But iceman is right. This is NOT an easy task...

[A4x]

How do you keep the cams in place when doing this job? Is there a special tool you install on the cams before you remove the valve cover but after you remove the upper timing chain cover?

[Theiceman]

use RTV on this and you are just asking for trouble.. you need to use an anaerobic flange sealant that will NOT vulcanize in the presence of oxygen... i used loctite 574

but if you are a gambler have at it.

[BradyBoi55]

use RTV on this and you are just asking for trouble.. you need to use an anaerobic flange sealant that will NOT vulcanize in the presence of oxygen... i used loctite 574

but if you are a gambler have at it.

Ive had rtv on for over a year now and no problems. But who knows. There might be some leakage in the future. Guess ill have to see lol

[Theiceman]

Ive had rtv on for over a year now and no problems. But who knows. There might be some leakage in the future. Guess ill have to see lol

I think you will be fine with leakage. Anaerobic is speced as there is no risk of it falling inside the engine after vulcanizing and blocking an oil galley.
I've seen it and it's ugly.

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[BradyBoi55]

I think you will be fine with leakage. Anaerobic is speced as there is no risk of it falling inside the engine after vulcanizing and blocking an oil galley.
I've seen it and it's ugly.

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It happened to a buddy of mine. Not from the valve cover but a oil return passage got blocked and it destroyed a rod bearing. I dont think I should have a problem. The sealant feels and looks as if it was new. Hopefully it doesn't vulcanize completely and block any passages.