How to be sure . . . . ? ?

[vhv5hss]

How to diagnose my issue??
Lately my 6 has been giving me cause for concern. initially what started as oil leaks in my driveway, followed by identified leaks in the lower tanks of both intercoolers, and then dicovering approx 0.6 liters of oil in the lower hose (one side only) when removed to replace, what is the projected diagnosis?
During driving, I have a bad 'thuddering' noise at the inside of my foot along with masses of white smoke when under hard acceleration only occasionally and clean running all other times. This noise occurs just at gear change (when hard boosting again) and clears as soon as throttle is backed off.
What symptoms does turbo failure produce, why not constant oil burn and what is the noise?
Clearly i am void of Vagcom or any diagnostic gear and drive 1 of only 22 C5 Avants bought into New Zealand new. It does seem as though qualified advice is scarce.
Any help, thoughts would be appreciated. Am i missing anything? Loose hose, clip popped off, hose split etc etc?????
Kelvin

[JCviggen]

I would not expect turbo issues to be intermittent, but white smoke upon hard acceleration is definitely very bad and should never occur. The water has to be coming from somewhere in this case the turbo housing is a good guess since it also seems to be passing a good deal of oil past the seals..... sorry

I believe turbo issues are relatively rare but if you have air leaks somewhere they can expire sooner due to over-spinning them.

[RS6Steve]

I'm going Turbo's... All the seals have gone! Just my 2p

There will always be some oil in the intercooler but on 0.6 of a lire!

[Shoppinit]

What JC said. Probably turbos expiring due overspooling because of leaky intercoolers.

Get some lobas on there :p

[vhv5hss]

Okay. So then. The confusion (to me at least) is why not constant smoke and oil burn if turbos are dumping oil into the compressor side? What type/brand are these turbos and what construction are they? Are they a plain/ball or roller bearing? Lip seals or rely on shaft to bearing fit to seal against oil pressure?
Sorry, seems a lot of questions but am feeling quite alone down here at the bottom of the world all of a sudden when even the Audi dealer looks at me blankly when probed . . . . . .
Thanks for the advice. Great forum ! ! !
K

[JCviggen]

KKK turbos, plain thrust bearing AFAIK (not even 360°) definitely not ball bearing.

It's certainly rare to have intermittent fluid passing from the cartridge but there is little else that could explain your problems. Oil into the intake pipes is 1 thing, white smoke is another. You are probably experiencing excessive turbo shaft play that gets worse as loads increase on it. If you continue driving it for long enough and hard enough you will probably experience a spectacular turbo failure at some point that removes all doubt. Not the most desirable of scenarios mind you because when the wheels hit the housing (in particular the compressor wheel) you can get all kinds of metal debris going through the intake.

Unfortunately the turbos are quite well hidden but need to be checked out. Even if the dealer has no RS6 experience I would expect them to at least understand something about turbos...should have seen enough 2.7T turbo failures I imagine. Those are less rare.

[vhv5hss]

Hmmmm. Confused now. What is this reference to water leaking as in your first reply? I can understand oil ingress and also the aspects of turbo wear but how would i be getting coolant fluid leaking???
Have talked again to the only Shop i would trust which is still inoperable after our earthquake in early Feb. This may end up being a job done in another Shop but using their guys.

Geez JC, as an aside the road trip from Moscow brings back some haunting memories. During my earlier days i engaged in steering trucks Stavanger across into Finland to fund my backpacking. Great time but certainly don't miss the Scandinavian winter driving experiences . . . . .

[JCviggen]

The reference to water leaking is water leaking into the exhaust from the turbo, creating white smoke. This indicates damage to the turbo's center section. It's about the only time you will get white clouds out of the exhaust, the other would be a serious head gasket failure but that would be white smoke continuously regardless of load so I think we can dismiss that.

Turbo's don't always fail in the same way, you can get big blue clouds if the oil gets passed into the exhaust for example. If the oil passes on the other side (the compressor wheel) it sends oil into your intake which is what seems to be happening in your case as well. A light oil coating in the IC pipes is normal (also because of the PCV system) but vast amounts are not.

The road trip was good fun if only the roads had been slightly less bumpy! lol. Not looking forward to driving it back, but at least there won't be any snow which makes for more relaxed driving.

[Cornishmoocher]

right.... i had both heads go on my 6... produced clouds of white smoke. repair bill... over £10k.
shortly after both Turbos went..... repair bill over £6k. both mine bo's started to howl, had no boost and produced huge amounts of oilywad.
shortly after my arse produced some involountary twitching and expired in a cloud of smoke and profanties. repair bill.... 1 bottle of spiced rum.

[bam_bam]

repair bill.... 1 bottle of spiced rum.

Consumed anally?

[chunky79]

repair bill.... 1 bottle of spiced rum.

Consumed anally?

The only way

[Cornishmoocher]

Yes, yes it was.....

[vhv5hss]

Um. Heck. Am not liking the sound of this ! ! The anal insertion bit i mean. . . . . . . .

The thought of pulling the engine dosnt really put me off too much but do want to do it for the right reason. And, a real reason. What do i do to be absolutely sure that i have a mechanical issue? What has me stuck is the inconsistancy. Why not everytime all the time??? What do i need too do to get, and use, this Vagcom software tool that you dudes talk about???

Frigging cars . . . . . .

[Shoppinit]

Have you got white smoke coming out of both exhausts?

[JCviggen]

Vagcom/VCDS might not show anything too unusual. The computers do not have a way of telling when a turbo is about to go pop, or other severe mechanical problems that don't involve a dodgy sensor or air leak somewhere. You need a laptop (doesnt need to be particularly new or fast) and a USB to OBDII connector. If you just want to check codes, you should be able to find suitable cables for 10$ a pop that will work with VCDS lite (99$ license) that's the quickest way to get one probably. The actual ross-tech cable and VCDS is more expensive (but more versatile) though the software is about the same.

At this point it is very safe to say that you do have a mechanical issue. At no time, ever, should you get a big white cloud or a pint of oil in an intercooler.

When the engine is out the turbos can be checked for play on the main shaft (difficult to explain without some sort of pun there)

To rule out head gasket issues you could do a compression test, that's considerably less work but it's probably going to come out OK. I'm betting on turbo(s) given the symptoms but make sure if they turn out to be an issue that you eliminate the likely cause of the problem (air leaks) and while the engine is out there are some things that are worth doing like front lambdas/EGT and a few other bits that would cost a lot more to do when then the engine is back in.