Hi,
I have a 96 GS that I have been working on here and there for about a year. I finally got it running but it is exhibiting some white smoke from the exhaust on occasion. Sometimes it does it when I first accelerate, and sometimes when I decelerate, but never 100% of the time.

I decided to do a compression test and got 148-150-150-151. I wasn't sure that I had the car warmed up enough, so I drove for about 20 minutes and tried again. This time I got 151-150-160-170. Weirdly enough, everything I have read says it should take 3-5 cranks to produce the result in each cyl. In my case it took about 20-25 cranks to get the number...

I also had the exhaust manifold off for a bit and looking at the inside of the ports, the head is chock full of carbon. Cyl 3 looked like a cave with carbon mounds choking the port. When I pulled the plugs, which are brand new, there was oil on the threads, and a few rubbery flakes on it. I also saw similar flakes when I drained the oil. I am also currently throwing codes p 1294 and p0352...

Thoughts?

Forgot to mention. The car does not overheat. There are no leaks as well. Any help/ideas would be greatly appreciated.

Are you sure it's white smoke? My guesses would be rings, valve seals, and head gasket, in that order.

I am pretty positive on the smoke being white, but it pretty much only seems to do it when I am driving and not when it idles in my driveway....

Do a leak down test. That will give you a better understanding.

shakeandbake said:

Do a leak down test. That will give you a better understanding.

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What he said. You need to figure out where the cylinders are leaking.

Ok, will do. Interestingly enough, I put on a pcv valve(not sure why one wasn't on there), and the check engine lights are off. Car didn't smoke on a quick drive. However, the car runs hot, now. Coolant level is good. Car doesn't overheat but the needle got to about 3/4 the way up(and stayed). Likely would have overheated had the radiator fan not turned on, but even with the fan on, the temp gauge wasn't coming down....

You'll know more once you do the leak-down test. We're just speculating until then.

Leakdown was 4-6% across all cylinders. I had a shop do it to make sure that I didn't do it wrong and they said that the rings and head gasket were fine, but if there were valve stem seal problems, that that wouldn't show in the leakdown.

So... Low compression, leakdown looks good. Has to be the valve stems, yes?

E-CLIPS97 said:

Leakdown was 4-6% across all cylinders. I had a shop do it to make sure that I didn't do it wrong and they said that the rings and head gasket were fine, but if there were valve stem seal problems, that that wouldn't show in the leakdown.

So... Low compression, leakdown looks good. Has to be the valve stems, yes?

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The leak down test should have ruled out the head gasket, but there can still be a dynamic issue with the rings. Those hot engine compression numbers concern me. Try putting a little motor oil in each cylinder and run another compression test, before tearing into the valves.

Not sure what you mean by a dynamic issue with the rings. And I can do a wet compression test, but I also am not sure what you mean by the "tearing into the valves" comment...

E-CLIPS97 said:

Not sure what you mean by a dynamic issue with the rings. And I can do a wet compression test, but I also am not sure what you mean by the "tearing into the valves" comment...

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Yeah, do a wet test to check rings.

I think Paul just mistyped on the valves comment

E-CLIPS97 said:

Not sure what you mean by a dynamic issue with the rings.

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That means a problem with the rings sealing when the pistons are moving. A leak down test won't catch that kind of problem because the pistons aren't moving.

E-CLIPS97 said:

but I also am not sure what you mean by the "tearing into the valves" comment...

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I mean rule out the pistons before replacing the valve stem seals. Was it really that unclear?

VelocitàPaola said:

I mean rule out the pistons before replacing the valve stem seals. Was it really that unclear?

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Yeah, I couldn't get "before" out of the "but".

Makes sense now

bullettdsm said:

Yeah, I couldn't get "before" out of the "but".

Makes sense now

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No worries, I didn't get the before from but either, but it does make sense.

VelocitàPaola said:

That means a problem with the rings sealing when the pistons are moving. A leak down test won't catch that kind of problem because the pistons aren't moving.

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So what causes this? And what's the fix?

E-CLIPS97 said:

So what causes this?

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Cracked rings. Worn cylinder walls.

E-CLIPS97 said:

And what's the fix?

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New rings. Honing the cylinder walls. Basically a rebuild.