Thread: Piston discoloration - 300Tdi

Pistons need approx .002" gap, the oil film on the skirt helps support it In the bore.

That pattern is normal.

That is the injector spray pattern you see.

Originally Posted by rick130

Pistons need approx .002" gap, the oil film on the skirt helps support it In the bore.

That pattern is normal.

Thanks! I can continue with the engine job

clean that surface of your block though. till its good enough to eat off. and check for warping whilst you have it all off. and ignore me if you already know all this. i used some additive to my fuel as well and the pistons were spotless. i forget which one. rick130 recommended it in a thread i believe. i think was redline r2-d2 or somethings starwarsy like that.

Originally Posted by Fausto79

clean that surface of your block though. till its good enough to eat off. and check for warping whilst you have it all off. and ignore me if you already know all this. i used some additive to my fuel as well and the pistons were spotless. i forget which one. rick130 recommended it in a thread i believe. i think was redline r2-d2 or somethings starwarsy like that.

Oh right, I never really thought that fuel additives would clean the pistons...
I used to use F-10 and now i will try the 'Fuel Doctor' additive once i get this new engine running.

I have cleaned the surface of the block thoroughly but i haven't sanded it or anything like that - should I? I don't really want grit or abrasive fibers going in the oil ports as it is not a total rebuild and the block wont be being washed out...

I used scotch brite and a soft wheel disc on my air tool. Cleaned it up nice and shiny. Don’t want anything too rough that will scratch block.

New Cylinder Head

Not sure if pics work anymore but it was a fairly soft spinning wheel and carby cleaner. You want block face spotless and test for flatness whilst at it. I think 5thou absolute maximum warp but i may need to be corrected on that.

Originally Posted by Fausto79

clean that surface of your block though. till its good enough to eat off. and check for warping whilst you have it all off. and ignore me if you already know all this. i used some additive to my fuel as well and the pistons were spotless. i forget which one. rick130 recommended it in a thread i believe. i think was redline r2-d2 or somethings starwarsy like that.

Redline RL2

The pistons and chambers were spotless on mine, too.

And ditto with the scothbrite and carby cleaner and get the deck immaculately clean.
And this is especially important if using an MLS head gasket.