Blue smoke at cold start

1994 PORSCHE 911
45,000 MILES • 3.6L • 6 CYL • 2WD • MANUAL
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SEVAG P
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Hi,

I rebuild an air cooled Porsche engine, new factory (mahle) cylinders and pistons installed, complete seals and gaskets replaced, now during cold start blue smoke appear for a while then disappear,engine run in after rebuild about 70 miles,is it the new rings still doesn't seated properly? manual doesn't mention after engine rebuild how many miles should be engine break in.

Thank you.
Jan 26, 2020 at 11:53 AM
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KASEKENNY
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They should not smoke at all after they are rebuilt. Clearly some may burn out some residual oil from the assembly process but that is just until after they warm up.

If it goes away after it is warm, I suspect the valve guides and seals are leaking. Normally when this is the issue the leak is very small and once the seals warm up they stop and the smoke goes away. Also, if you shut it off and restart it, it will not smoke because the seals are warm.

If it were me, I would replace the valve stem seals and retest it. If this doesn't do it then it is the rings.

https://www.2carpros.com/articles/blue-smoke-from-engines-exhaust
Jan 26, 2020 at 3:18 PM
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SEVAG P
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Hi,

Then engine doesn't need further break in,because we just drive about 70 miles??
Jan 26, 2020 at 8:51 PM
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