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Blue smoke when idling; turbo?

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, 850 R, 850 T5-R, 850 T5, 850 GLT
1997 - 2000 S70, S70 AWD
1997 - 2000 V70, V70 AWD
1997 - 2000 V70-XC
1997 - 2004 C70

JimBee
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Blue smoke when idling; turbo?

Post by JimBee » Thu Jul 28, 2016 5:17 pm

Recently, while driving around the city slowly on a couple of errands, I've noticed that if I'm idling for long traffic light or otherwise waiting in a line for 4 or 5 minutes, quite a lot of blue smoke starts from the tail pipe.

I don't see any on start-up and never on hard acceleration like kicking it down getting onto the freeway, and the oil level isn't going down.

I'm wondering if the smoke has something to do with the turbo.

Any suggestions?

tryingbe
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Re: Blue smoke when idling; turbo?

Post by tryingbe » Thu Jul 28, 2016 5:32 pm

Year, make, model?

Oil level not going down? How about coolant level?
85 GLH, 367 whp
00 Insight, 72 mpg

JimBee
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Re: Blue smoke when idling; turbo?

Post by JimBee » Thu Jul 28, 2016 9:33 pm

It's a 96 850 turbo auto trans. Dyno oil.

Oil is staying full. Actually, it might be a bit overfull, right to the top of the flat end of the dip stick where it was after last time I changed it. I've only been driving that car a couple hundred miles a month, if that much. The oil does seem clean, no froth or any sign of anything else that I'm aware of.

The coolant level goes down a little every hundred or so miles, not sure where that's going. There's no obvious leak and no white smoke out of the exhaust.

At idle, when I've been driving around slowly and the engine is hot, oil is igniting somewhere internally and going out the tail pipe. It doesn't puff blue smoke like you might expect after driving at highway speeds, or goosing it for short distances.

There aren't many ways oil can get into the combustion chamber(s), either up from the bottom through the cylinders, or down from the top. I doubt it's coming up from the bottom past the rings (which are new) it would be smoking at acceleration and at start up after highway driving and the oil level would be dropping.

If it were draining down through the valve guides/seals (which I assume have not been replaced), wouldn't I see tail pipe smoke when I start the engine after sitting over night. I watch for that and it always starts with no smoke. Probably unrelated, but on really muggy, hot days, although the engine temp stays right at 3:00 o'clock, the exhaust seems unusually stinky.

I suppose the turbo gets hot enough to ignite oil that might be leaking in there, or oil in the turbo could ignite in the cat. But why would it only leak during idle (after idling for maybe 4 or 5 minutes) when the engine is hot and has only been driven gently around the neighborhood? Like I said, it doesn't happen during or after aggressive acceleration or driving at highway speeds.

The smoke is clearly from burning oil and quite a lot at idle. When I rev the engine and get back under way it completely clears up.

Thoughts?

tryingbe
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Re: Blue smoke when idling; turbo?

Post by tryingbe » Thu Jul 28, 2016 10:05 pm

Check the turbo for shaft play, if shaft play is minimal and no wheel contact with the housings, valve stem seal are probably worn.

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85 GLH, 367 whp
00 Insight, 72 mpg

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erikv11
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Re: Blue smoke when idling; turbo?

Post by erikv11 » Thu Jul 28, 2016 10:05 pm

Leaky P80 turbos are very rare. Leaky P80 valve stem seals are very common. Just saying ...
'95 854 T5-R, Motronic 4.4, 185k
'96 855 NA, 145k
'98 S70 NA, 220k (living out west)
'98 V70, T5 tune-injectors-turbo, LPT engine, 285k
'06 S60 R, 165k
'99 Camry V6 :shock: 125k
gone: '96 NA 850 210k, '98 NA V70 182k

JimBee
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Re: Blue smoke when idling; turbo?

Post by JimBee » Fri Jul 29, 2016 10:11 am

Maybe a thousand miles ago I checked the turbo shaft. It spun freely with no end or side play. The oil lines in and out were clean. It has had clean oil before that and since. Unless something catastrophic happened the shaft should be okay.

So, yeah, those valve stem seals would be suspect. I actually have a 2.3 cylinder head pulled from a junker that I could rebuild and just swap it on. It's just sitting in inventory, so I might do that (sometime ; -). That head has a couple of bent valves. I had the planed surface checked for trueness and it was within spec.

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Re: Blue smoke when idling; turbo?

Post by tryingbe » Fri Jul 29, 2016 10:35 am

It's easier to swap the valve stem seals than change the head.
85 GLH, 367 whp
00 Insight, 72 mpg

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Re: Blue smoke when idling; turbo?

Post by beigg » Fri Jul 29, 2016 12:47 pm

Either way, timing components will need to be removed and then repositioned. Removing the turbocharger to fully inspect its condition wouldn't hurt at this point for your particular situation.
ugh smh 850 Turbo fridge

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