enter image description hereSo today I cranked the engine I was rebuilding (Skoda Estelle/120 '72, RWD, rear mounted engine) and while it started, yes, but not without some struggling, I got a lot of white or light grayish fumes. I first did a crank without water, just to see how it goes, and got this kind of smoke but very subtle, out of the water pump and thermostat casing. I guess it is just paint, mounting oil, etc being fried. So the next crank I put the out hose into a bucket: I didn't get bubbles, so I guess compression is not going into the cooling system. But I do got lots of smoke.

I could inspect the chambers visually by looking through the sparkplugs holes: I see some oil there. I wonder if this is because the rings, or it is because I may went too happy with oiling the cylinders when building the engine. In any case: light gray fumes.

Sparks 1, 2, and 3 got a little bit of oil, park 4 got a lot of black carbon. Oil pressure at ~1.500 to ~2.000 rpm is between 4-8 kgf

So: rings? lean carb? mounting oil? wrong timing?

  • 2
    Perform a leakdown test?
    – Ben
    Commented Sep 23, 2017 at 3:07
  • I'm wondering if the rings have fully seated. You may need to go to extreme measures to get your rings to seat. IIRC, you have non-conventional rings, right? Commented Sep 23, 2017 at 12:05
  • 1
    @Paulster2 yes, non-conventional rings. What do you mean with extreme measures? Commented Sep 23, 2017 at 16:48

2 Answers 2


Did you do anything to the exhaust like a cat delete or header wraps? My car had both done and puts out a white smoke like that as well, not sure if it’s the Same problem though

  • Nope, all is fine there... Commented Sep 23, 2017 at 16:48

I would check the oil level and let the engine run for a few minutes. If the smoke stops, stop the engine. After about 5 minutes have passed or the smoke has stopped, check if your oil level is the same and re-inspect the cylinders. If there isn't any oil in the cylinders, you are probably ok. If the oil level has dropped, your rebuilding failed...

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