Well here's a strange one.

[Opticon]

Car suddenly bogs under a few PSI boost and begins smoking under decel and idle. A problem I fought before and eventually ended up fixing (or patching) with a better PCV setup.

Well this time no amount of PCV fiddling made a difference. No engine stutter or miss. Spark plugs are clean. Compression is good. Coolant system hold pressure.

Crawl under the car and look up at the exhaust manifold...

http://i.imgur.com/08ldKKJ.jpg

Hmm.

Could a blocked oil return hose backfill into the exhaust manifold? Or did I crack an oil passage leading directly into the manifold?

[cordes]

A blocked off oil return could do that. It could also be the oil seal on the turbine side has just went out. That's where my money is. I can't see oil making it through the manifold in liquid form like that without toasting the engine in short order.

[Shadowv4l]

So much for the new turbo.....

[shackwrrr]

Ill just throw the idea of a dropped exhaust guide in here. Im trying to figure out how turbo oil could make it up to the manifold working against the flow.

[Turbo224]

Yeah, blocked oil return line seems possible, and is certainly the easiest to check. That's where I'd start.

[Reaper1]

Yeah, I think I agree with the dropped valve guide. The smoke on decell is a clue that would make me look there first.

[turbovanman²]

Dropped guide won't produce that much oil. I am afraid if your return isn't plugged the turbo is done. Check for free play, bet you can row a boat with the shaft.

[85boostbox]

Yep turbo is toast. Oil will come out above like that because under a hard decel there is no real exhaust to speak of.

[turismolover22]

Last time i had that much oil i was making aluminim shavings with the compressor wheel.Soirry about the bad luck my votes on a turbo

[Reaper1]

I'd agree on the bad turbo thing, except that it only produces smoke on decel. I can understand that there's not a lot of exhaust energy while slowing down and that can lead for oil to make its way into the exhaust and the manifold. The thing is that I would think it would smoke worse under acceleration due to raised oil pressure and the shaft wobbling all around letting all the oil go by. This doesn't seem to be the case here.

I will say I am fortunate enough to have never experienced a bad turbo, so I would be grateful if somebody could enlighten me to this diagnosis, or point out where my flawed thinking is. I could really be missing something pretty darn simple...it happens.

[Shadowv4l]

I can't wait to start taking it apart, its just to damn cold to bother right now :/

[turbovanman²]

I'd agree on the bad turbo thing, except that it only produces smoke on decel. I can understand that there's not a lot of exhaust energy while slowing down and that can lead for oil to make its way into the exhaust and the manifold. The thing is that I would think it would smoke worse under acceleration due to raised oil pressure and the shaft wobbling all around letting all the oil go by. This doesn't seem to be the case here.

I will say I am fortunate enough to have never experienced a bad turbo, so I would be grateful if somebody could enlighten me to this diagnosis, or point out where my flawed thinking is. I could really be missing something pretty darn simple...it happens.

To get that much oil visibly leaking out of the joints, you'd need a butload of oil, a dropped guide will NOT do that, unless the guide is cut down for porting but then if the guide did drop down, the valve would bang around and mostly also drop causing catastrophic engine failure. The next logical item is the turbo, its under oil pressure so when the turbo goes, oil leaks into the exhaust. As for smoking on decel only, no idea but when a few of mine went, it would only smoke under hard accel.

[OmniLuvr]

i would pull plugs to see if oil is actually being burnt in combustion chambers, pull the intercooler hoses also, and might as well pull the air filter and check for shaft play.

and simon, yes, exhaust guide/seal issues WILL cause this much oil leakage into the exhaust tract. sometimes you can even see it escaping from the exhust port that is the culprit.