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Leaky valve stem seals

Help, Advice and DIY Tutorials on Volvo's extremely popular car line -- Volvo's 1990s "bread and butter" cars -- powered by the ubiquitous and durable Volvo inline 5-cylinder engine.

1992 - 1997 850, including 850 R, 850 T-5R, 850 T-5, 850 GLT
1997 - 2000 S70, S70 AWD
1997 - 2000 V70, V70 AWD
1997 - 2000 V70-XC
1997 - 2004 C70

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rmorse
Posts: 114
Joined: Mon Aug 01, 2011 10:36 am
Year and Model: 96 855R
Location: Maryland

Leaky valve stem seals

Post by rmorse »

Hey all,

I have blue smoke after long idle, compression is GOLDEN. 178 to 180 on every cylinder. Car has ~125k miles on it, 1996 855R. Entire PCV system was changed about 4 months ago.

So, question....How soon do I have to fix the stem seals? Also, what happens if I don't fix them for another year or so? This jobs scares the piss out of me. Most advanced job engine-wise I have done is the timing belt on my 98 V70. I have changed the entire front end before (struts, LCAs, tie-rods, axles, etc) but I have never opened up an engine before so this scares me. I kinda want to put it off as long as possible. The car doesn't seem to be using much oil, btw. I have driven about 500 miles since the last oil change, no noticeable change in oil levels.


TL;DR: Will I hurt my engine if I drive around with bad stem seals.

jimmy57
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Post by jimmy57 »

Not likely to be valve stem seals.
Was the kit for crankcase breather OEM or URO? The Uro stuff often has hose failures.
Turbo leaking is far more likely. Oil burned through engine usually produces no smoke but turbo leak directly into exhaust will cause smoke with low leak amounts. is the exhaust pipe connection to turbo showing oily residue?
One of the seals in exhaust side of turbo is a miniature piston ring. It can get stuck in its groove and let oil past that goes straight into exhaust.
You may be a good candidate for Seafoam treatment. There are lots of how-tos on here for that.

jwebster
Posts: 20
Joined: Mon Sep 12, 2011 9:03 am
Year and Model: 2000
Location: Dallas

Post by jwebster »

If it is valve stems, there is no real concern other than the oil consumption. Keep an eye on your oil level so that it won't run dry. The repair is easier than you think. The biggest thing you need on your first engine repair is time. If you have time, then with a little research you'd be completely competent. Jimmy57 is probably right about the cause of the smoke. If its the valve stems it can create the amount of smoke you are speaking of but the oil consumption would be very noticeable.

jblackburn
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Post by jblackburn »

I disagree. Blue smoke does mean that you're burning oil in the combustion chambers, so the turbo isn't leaking it into the exhaust- that would produce grey smoke.

I know for sure that I have leaky valve stem seals, and I do get an occasional small puff of blue smoke on start-up, but usually nothing noticeable after idle or on start-ups after the car has been driven within a few hours. My car burns about 1 qt/3000 miles.

To answer your question: leaky valve stem seals can eventually lead to burned exhaust valves. That usually happens when it gets very, very leaky and starts burning a ton of oil. I have chosen to ignore mine for the past 50,000 miles as it's more effort than I have time to put into it right now, and oil consumption really hasn't gotten any worse at all.
'98 S70 T5
2016 Chevy Cruze Premier


A learning experience is one of those things that says, "You know that thing you just did? Don't do that."

mercuic: Long live the tractor motor!

jwebster
Posts: 20
Joined: Mon Sep 12, 2011 9:03 am
Year and Model: 2000
Location: Dallas

Post by jwebster »

I'm taking both of you at what you propose because I don't know about the turbo. Burnt oil being turned into grey smoke is the difference between these two opinions and I'm just not aware how blue smoke can be turned into grey. My experience with valve stems is that there is so much pressure in the engine that there is no slow leak. But it could be just that in this case. You'll know when you get in there.

boosted5cyl
Posts: 1100
Joined: Fri Jan 29, 2010 12:52 pm
Year and Model: '98 V70 T5, '99 S80
Location: St. Paul, MN

Post by boosted5cyl »

Smoke after long idle is not likely to be valve stem seals. Its typically elsewhere if its after a long idle period.
Does it smoke immediately when you start it up after sitting for while? If not, its pretty unlikely to be leaky stem seals. Usually the seals first manifest themselves by leaking oil into the cylinders when the motor is stopped, then when you next start it, this oil is burned off. Burning oil after a longe idle period is more likely to be turbo related. In extreme cases the oil will leak past the stem seals at idle to an extent that its visible, but in this case it will still leak when the motor is stopped, so you will still get the smoke on startup no matter what.

It doesn't have to be a major cause for concern, but for sure keep an eye on it. Also, your compression and still be good with poor oil control rings, which can lead to oil burning too.
'04 XC90 2.5T AWD (Angus) 134K.
'99 S80 T6 (Medusa) 214k. On borrowed time LOL
'98 V70 T5 (Vivienne). RIP @ 228K. Spun rod bearings.

Klausc
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Post by Klausc »

Everything Jblackburn said is correct. When a turbo leaks oil directly into the exhaust, the smoke will appear as a white cloud! Just like watching an air show and seeing the old planes leave a trail. Most white block turbos will leak oil on the intake side, which gets drawn to the throttle body eventually. Some of that oil will condensate in the intercooler and your long idle could be letting that oil heat up and get burned. You could pull the lower hose off the IC and check for standing oil.

If you ever decide to get new valve stem seals, bring the head to a very good local machine shop and let them recondition it for you. All 20 valves and seats and seals. They will do a better job than any shade tree mechanic could ever do. While the head is off, you could rebuild the turbo.
Klaus
If I had a larger garage, I could have more Volvos.

rmorse
Posts: 114
Joined: Mon Aug 01, 2011 10:36 am
Year and Model: 96 855R
Location: Maryland

Post by rmorse »

Wait wait wait. Now I'm mega-confused. Everything I have read says that blue smoke after long (20 min) idles is valve stem seals. I would be thrilled if it is the turbo, since I want to upgrade it anyway. There is no puff at startup.

When I take the pipe off the top of the engine that goes into the turbo, there is definite oil buildup.

jblackburn
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Post by jblackburn »

Some oil in that pipe is normal, but they shouldn't be oozing oil at the connections to the rubber pipes on the way down to the intercooler.

If it is, I'd be looking at the PCV system hoses again. Is there positive pressure again? Is everything still connected as it should be? As Jimmy said above, the URO kits are junk.
'98 S70 T5
2016 Chevy Cruze Premier


A learning experience is one of those things that says, "You know that thing you just did? Don't do that."

mercuic: Long live the tractor motor!

rmorse
Posts: 114
Joined: Mon Aug 01, 2011 10:36 am
Year and Model: 96 855R
Location: Maryland

Post by rmorse »

Ok, I'll give it a look-see. Just as a refresher, what is the best way to check the PCV? There is no smoke coming out of the dipstick...

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