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Discussion Starter · #1 ·
So shortly after installing a turbo back (catless) exhaust on a 2001 XC70 it began smoking at stoplights. Initially an Indy mechanic stated it was the turbo seals because there was oil in the intercooler pipes. While installing new intercooler hoses I looked, yes there is a little oil in the intercooler pipe but not enough to make me believe it was the turbo. Pulled the over engine intercooler pipe, shine a light into the turbo compressor housing and it's nice and shiny, no coating of oil, no puddle, nothing... that makes me think the compressor side is good.

While installing the turbo back exhaust I expected to see some evidence of oil leak from the exhaust side of the turbo, looking directly into the turbine housing on the exhaust side it looks like any other turbo, just exhaust soot and just your noticeable surface rust.

I believe the actual problem is valve stem seals leaking into the cylinders. I would love to hear some input to make sure my logic on the matter is sound before tearing into this thing :)
 

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Since it's so simple to do, I'd suggest a compression test. If the compression is solid then you're on the right track. If you have low compression in one or more cylinders then it could be rings.

You're probably right, but a compression test can verify it.
 

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Are you sure it's oil smoke? I assume you've checked the pcv system.

From my experience, a leaky valve stem seal will cause a lot of smoke at start up until it warms up.

Is it a lot of smoke?
The ECU will swing AFR at idle to diagnosis cat health by comparing front and rear O2 signals during the swing), as well to keep the cat operating properly. Could be unburnt fuel that you're seeing when letting off of the throttle, but I'm not sure. I've never ran a Volvo without a cat.

Also came across this thread a while ago. Could help for clues.
http://forums.swedespeed.com/showthread.php?195339-Oil-smell-smoke-after-coasting/page2
 

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Discussion Starter · #4 ·
I know the dip stick trick for checking the PCV system, but haven't given that a try yet. I know those are notorious on these cars, but seeing as how the PCV system was just replaced within the last 3 years my mind ruled that out :/

I'll report back after testing the PCV
 
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