PCV pressure

FastYellow · Post by **FastYellow** » 04 Feb 2016, 15:46

Will a really bad clogged PCV system cause smoke out the tailpipe?
Thanks.

Post by **FLXC90** » 04 Feb 2016, 16:07

Not directly, no. When the PCV clogs, it actually prevents drawing oil vapor back into the intake and burning it. A clogged PCV will cause excess pressure in the top end,( where oil vapor should just re-condense to oil and drip back to the sump) normally resulting in leaking oil seals.

A clogged PCV can, (CAN not does) indicate a general lack of maintenance, or a lack of specific maintenance, which may lead to oil smoke out the tailpipe

When does the smoke occur, at idle, at revs, on deceleration, acceleration? This can help determine where the oil is coming from.
Other diagnostics, Compression test, leakdown...

FastYellow · Post by **FastYellow** » 04 Feb 2016, 16:24

It occurs when rev'd after its been warmed up and idling for a bit.
I know it needs PCV system replaced.

Post by **FLXC90** » 04 Feb 2016, 20:01

As I recall, revving after idle sounds like stem seals, oil builds up, you rev and blow it out. I'm not sure about turbo seals, possibly them too.

Now the rest of the intake information:
How long have you had the car?
How many miles?
Maint history?

We'll be able to talk more intelligently after we know these things

Post by **erikv11** » 04 Feb 2016, 21:51

Yes!

Without proper drainage back into the oil pan, lots of oil collects in the intake, then gets into the combustion chambers (cylinders) and you get blue smoke out the tailpipe.

With the buildup in crankcase pressure on the top end, even more oil gets pushed past the valve stem seals, which similarly burns and gives blue smoke.

Likely the engine has worn valve stem seals, it's getting up there. You can still drive it like that. But driving it very long on clogged PCV will be the end of it, think constantly blown cam seals, poor performance, oil in the cat. I'd check/fix the PCV if you're going to keep driving it.

Post by **FLXC90** » 05 Feb 2016, 12:00

Thanks Erik, I stand corrected . I would also suggest doing a seafoam treatment through the intake to clean away deposits, and ATP AT-205 to re-plasticize your valve stem seals, as well as PCV service.

Post by **misha** » 05 Feb 2016, 17:54

I agree with erikv11.
I had clogged flame trap which produced blue smoke from the exhaust and excessive oil consumption a long time ago.
Cleaned all of it,removed flame trap and all of that disappeared.

FastYellow · Post by **FastYellow** » 05 Feb 2016, 18:29

I picked up my Gul Yellow T5R from original owner who had it since new. I am slowly getting the car to stage zero.
227k on her. Just performed timing belt, hydraulic tensioner, water pump and rollers with Volvo parts. The car fires up and runs great. I changed distributor cap n rotor and uses Volvo OEM plugs. There were oil leaks due to rear camshaft seals that have also been replaced by me using OEM Volvo seals.
Car has also new coolant reservoir and coolant.
Now I noticed the car smokes through dipstick. And also blue smoke comes out tailpipe when revved after warm.
I thought it was because of a dying turbo
Dry Compression numbers are cyl #1 150 cyl #2 145 Cyl #3 150 Cyl #4 155 Cyl #5 150
What do you guys think.
Thanks for all your knowledge

Post by **misha** » 05 Feb 2016, 18:32

I would say valve stem seals are bad.

Post by **rspi** » 06 Feb 2016, 07:33

Pretty good compression numbers. Was the engine hot?