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[archiewood]

This is also posted on vauxon.

I'm stripping down an X30XE. Whipped the heads off and all was well except number 6, the head of which was covered in a mm or so of black gunk. The sparkplug was also covered in soot (the others were OK).

Couple of things:

1) What could have caused this? The bore looked clean enough so I'm thinking the piston rings are probably OK, but the cam cover gasket for that bank was leaking pretty badly, so I'm thinking perhaps it was a combination of that and a loose sparkplug? If not, valve stem seals maybe?

2) How can I clean the piston without getting crap down the sides?

The engine is a transplant so I don't know how it was running before, but I'm told it was smooth enough and no smoke was mentioned. It's done about 100k, and the gaskets were fine.

[Marks DTM Calib]

The old trick was to put a pit of grease in the gap between piston crown and bore with the piston at tdc and then scrap the gunk off.....wind the crank round to take the piston down and clear the grease off.

It could be black for a few reasons....if its down to stem seal (not usual on the 3.0) then you would see crud on the valve stems.....its more likely to be a poorly firing cylinder or one that was down on compression (e.g. a loose spark plug)

[archiewood]

Ok, cool. I haven't got a look at the valve stems yet, but that's next on the list. Thanks for the advice about the grease, I'll definitely use that.

[Marks DTM Calib]

Ok, cool. I haven't got a look at the valve stems yet, but that's next on the list. Thanks for the advice about the grease, I'll definitely use that.

If you look in the exhaust and inlet ports of the head.....you will see the stems and be able to tell if there is an issue.....without removing the valves