Your compression is good and if the intercooler piping doesnt have oil in it, we can rule out the turbo/ too much crank case pressure. I would say your valve stem seals are bad.

 

No. .200mm is .008". Sparkplug gap is .020"

Compression is fine for cold engine.

 

so it should be 0.020” equals 0.50mm?

 

Compression test; did you add oil to see if the numbers increased ?

 

evoryder and letsgetthisdone are on the right track.

what cylinders look like that? do they share an ignition coil? Those are definitely badly oil fouled. Valve stem seals are likely. if you have a boroscope you can peek into the cylinder with it and look at the piston walls to see if they are gouged. I doubt it though due to your compression numbers.

Valve stem seals are likely and typically will leak oil into the combustion chamber when the engine is off as the oil drains back down to the pan. A key indicator when they fail is blue smoke at start up that clears up when the car gets warm. bad stem seals will not show up with leakdown/compression test.

 

cylinders 1 and 2 have a little bit of oil sat in top of the cylinder. I did borescope and couldn’t see anything obvious with the cylinder walls. As for blue smoke, there is a little on startup, so from what your saying, there’s my issue?

many thanks

 

Leak down test

 

nope. Will try that. Cheers

 

Going off what has been said above, that won’t show if stem seals are passing?

cheers

 

Does it smoke when you were under WOT? Hopefully it's the valve stems and not the oil piston ring failure. Let us know how it goes with the new plugs in.

 

I can’t say as I’ve noticed tbh. I’ve read there’s a tool that allows the seals to be replaced with the head in situe?

 

Yes, something like this.

https://www.euroexportinc.com/mitsub...alve-seal-kit/