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1988 mk3 Supra 7mgte auto, almost 120,000 miles
Runs good but smokes very bad especially after boost. New head gasket and had the head redone and machined 1000 miles ago. compression tested and 5 were 150-180 psi and the 1st cylinder was 120 psi being the lowest.
So my question is what could be causing the smoke? The piston rings are worn no doubt but the compression seems solid except for the 1st cylinder but it really smokes a lot more than one cylinder of blow by that’s for sure. Maybe bad turbo? Or valve seals? Or pvc? I installed a catch can after hoping it would help and it did not. Any feedback would be appreciated the smoke is pouring out of my valve cover exhaust side and cam position sensor And is white. The car doesn’t overheat. I really don’t have the time to do a whole rebuild on this motor right now and am hoping it’s not the rings as the car still runs and drives good but when you come to a stoplight smoke is pouring out your hood. It leaks oil too and oil get in my spark plug galleys and I have no idea how and I have to change plugs often. Also in my intake tubes, probs turbo, I don’t think a blown turbo would cause as much crankcase pressure as I’m getting tho.
 

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so the smoke is coming from where?
if you have a new head gasket they should have done new valve cover gaskets too so you shouldnt be leaking oil into the plug tubes. check to see if the VC bolts are tight.
take your oil cap off and see if you get a lot of blow by but the best thing to do would be a leak down test.
also, you have a 30 psi spread between cylinders, i'm not sure what stock compression is on a 7m but 30 is a pretty big difference.
 

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  1. Valve cover, small puffs of smoke out of oil cap when I take it off, I did leak down test but only first cylinder and some air was getting past rings into crankcase.
 

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Turbo oil seals. Smoking after boost and also on startup is a sign. If you can take the intake pipe off and check the turbo for side to side play that is a start. Oil all up in intake can also be a turbo oil seal. Both sides (exh and intake) can leak.

Prob a combo of oil puking out (valve covers) and ancient turbo seals
 

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Fix those valve cover leaks. One of my college mk3's had a horrible valve cover leak that produced under-hood smoke similar to what you describe.

Catch can shouldn't be needed to not smoke. Start with basics first. Get rid of any oil leak you can find in the engine bay.
 

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Discussion Starter #6
Thank you for feedback looks like I’m getting a new turbo👍🏼and tighting down valve covers first. Hopefully rebuild the bottom end next year if problems persist
 
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