1997 850 glt Serious Engine Smoking Upon Deceleration

1ezliving4ume · Post by **1ezliving4ume** » 25 Jun 2015, 15:29

Well the 850 with turbo has got a big issue. When I let off the gas a big plum of smoke comes out the exhaust pipe....weird. It does not smoke at on acceleration or if its just running. The PCV was just replaced, I do need a new coolant box so I can't tell if its coolant or motor oil. My guess in coolant. I have just ordered a new coolant box to help with the diagnostic of this issue.

My guess is the something in the turbo is not correct. ideas?

Post by **FLXC90** » 25 Jun 2015, 16:18

get a white towel or sheet or t-shirt. one person revs the engine, other holds cloth a few inches behind the exhaust, what kind of staining do you get? Also, is the cloud bluish, or white-white? How many miles on the car, and what is recent maint history?
Also, you say the PCV was just done-by you or a shop? If it was a shop, are they Volvo savvy? It is possible to misroute lines when reassembling the system. Try the glove test on your Cam cover, see if the PCV is pulling when it should.

Look in the database and check the turbo shaft for play.

Let us know what you find.

1ezliving4ume · Post by **1ezliving4ume** » 25 Jun 2015, 17:44

The car has 200,000. miles on it. the PCV was and is correct, I did it. I like the white cloth trick! we will try it. The problem is that it only seems to do it under load. If I just rev it it doesn't seem to smoke...weird

I will let you know and I will check the data base....

Post by **erikv11** » 25 Jun 2015, 23:31

One of my cars did this when I bought it, due to horribly clogged PCV. Did you ream out the passageway from the oil trap down into the oil pan? If this started immediately after you did the PCV then that is definitely the first place to look.

Post by **abscate** » 26 Jun 2015, 04:20

A big puff on overrun is often caused by worn valve guides or seals. Not too bad a job but a long weekend. Parts relatively cheap

1ezliving4ume · Post by **1ezliving4ume** » 26 Jun 2015, 06:51

The PCV is good. No dipstick smoke and it sucks the glove in.

Talk to me about how worn valve guides/seals would cause smoking on decel. I don't understand the relationship.

Why would it not be a seal in the turbo?

Seaway · Post by **Seaway** » 26 Jun 2015, 07:05

When my turbo was shot, it smoked on deceleration. It was easy to check the turbo for shaft play by disconnecting the intake and reaching in and simply trying to move the shaft in and out. Mine had a ton of play. Replaced the CHRA and all has been fine since.

Valve seals will smoke on startup as well.

1ezliving4ume · Post by **1ezliving4ume** » 26 Jun 2015, 11:31

Seaway,
This is my first turbo car so I don't know much about turbo's. What is the CHRA and what constitutes a ton of play? A 1/4" or an 1" or ?

Post by **erikv11** » 26 Jun 2015, 13:45

1/4 inch would be a ton. There should be very little play, like millimeters.

CHRA = Center Hub Rotating Assembly. It is the guts of the turbo, the part that spins and compresses air, connecting the hot and cold side of the turbo. It an be swapped separately or rebuilt.

Post by **misha** » 26 Jun 2015, 13:47

I would check a turbo first.
If it's ok then compression test would be next for piston rings check.
Valve stem seals can cause a puffs of blue smoke,but not on those conditions you allready described.