mjwolsky

I have a '82 930 with a K29 turbo and a 1 bar spring. Recently I have noticed some blue smoke in the rearview mirror when I let off the gas. I had a buddy drive it while I followed and noticed it puffs a little smoke when he lets off the gas and a little when changing gears but not when idling or accelerating (either while accelerating gently or while using boost). The engine still pulls just as hard as it always has and doesn't seem like it has any less boost than it has had in the past. Is this most likely turbo seals going bad? Any reason why I can't keep driving it as is or will I damage something by not getting this fixed right away? Also, if the smoke was due to piston rings, wouldn't it smoke all the time, not just while letting off the gas? What symptons would valve guide wear look like?

Thanks for any advice you might be able to give!

A930Rocket

I would say worn valve guides (and maybe seals). If it's not too bad, you can keep driving it. At least until it looks like the bug man coming through the neighborhood or your spark plus start to foul out too much.

There's a way to check valve guide wear by loosening the rockers and trying to wiggle the valve stem with a screwdriver. I don't recall the amount of play, but it will give you an idea if they are worn out.

mjwolsky

I read somewhere that overfilling the oil can cause the Intercooler to collect oil and smoke for quite a while. When my mechanic changed the oil before I put the car away for the winter last fall, he overfilled the oil and I took it in this spring to have him drain some out. This is the first year I have noticed that it smokes while letting off the gas and also smokes more than I remember it doing in previous years when I start the car. I removed the IC tonight and let it sit in it's side for a couple hours and there is at least 2 or 3 ounces of oil that collected in the end of the IC. How much oil normally collects in an intercooler? I am going to clean it out really well, reinstall it and see if there is noticeably less smoke. Maybe it's not worn valve guides or blown seals on the turbo, but just a bunch of oil in the IC??? Any thoughts?

Mark Houghton

This topic (oil in the air passages and turbo compressor pipe) was discussed just recently. General consensus from a fair number of follks is that a small film of oil in the IC seems fairly common, probably due to most motors having a fair number of miles on them. But 2 to 3 ounces is way too much in my opinion. If you know for sure that your mechanic did indeed overfill your oil, then that's most likely the culprit.

After cleaning it out, you may still see smoke for awhile until all the excess oil leaves other areas that are similarly coated (all airways post-air cleaner).

Geoffrey

It may very well be the seals in the turbocharger going bad. I see this most frequently.

mjwolsky

Thanks for the feedback! I'll have to do a little more digging around to figure out if it's turbo seals going bad. It's a KKK k29 turbo. Would you recommend having it rebuilt or just buying a new one? If rebuilding it is the way to go, who would you recommend I use? Thanks!

A930Rocket

Kevin at Ultimate Motorwerks.

The K29 is a big huffer. What mods do you have? There are newer turbos out there that might be better suited to your car.

mjwolsky

It has 3.4L yellowbird pistons and sleeves, an aftermarket intercooler with no markings on it but I think it is Billy Boat, B&B dual exhaust system and headers, the bigger turbo, fuel enrichment, adjustable wastegate, that's all I can think of right now.

onboost

Post some couple of pics to include engine shots

mjwolsky

Here are a few pics that I took last year:

drmatera

sweet ride. my buick GN would smoke on decel when the turbo was going bad.

mjwolsky

I had to order a couple O rings for each side of the intercooler. When I get everything put back together and up and running I'll post what I find...hopefully no more smoke!!

mjwolsky

The O rings came today! I got the intercooler put back on, got her warmed up and drove her around for a while and gave the turbo a good workout. I hardly noticed any smoke at all like I did before. I pulled the Intercooler off when i got home and let it sit on its side for 10 minutes or so and about a teaspoon of oil had collected in the inlet. I'm guessing that's from residual oil in the other passageways working its way through the system like Mark Houghton had pointed out. I'll keep an eye on it for the rest of the summer and with any luck the valve guides are just fine and the turbo seals are still intact. Thanks for all of the feedback and advice!

Quick question - When you overfill the oil, how does it manage to get past the turbo and into the IC? Is it due to too much oil pressure forcing it past the seals?

Mark Houghton

What the hell is THAT! Certainly not duct tape? Shame on you!

Overfilling on oil should not cause the turbo seals to blow or push oil by them. An over-full oil tank can overflow into the air box via the vent hose attached, sucking that oil through all airways. That's my understanding, though I've never experienced it.
I've always got a small oil film visible in my IC pipe after the turbo, as do many people. Just a sign of a nice, loose, powerful engine and I live with it. With any luck your issue will go away with the IC cleaning and the now proper oil level. If not, then seals or guides as already mentioned.

mjwolsky

LOL! No, it's not duct tape. =) I think it is just the way the light is reflecting off a scratched surface. Thanks for the explanation.

Mike