Head bolt leak.

[Ian Williams]

This is an interesting thread, like Jim I have in the past lapped heads and blocks, fitted gaskets with a smear of grease and not had issues. More recently I have been having the top of the blocks and heads very lightly skimmed by the machine shop who do my reboring, they obtain a nice fine finish and only remove the barest minimum of metal. However I have recently started to discover issues both on engines I have built and on engines where head gaskets were fitted by others. There is evidence of water seeping across the gasket into the bores, this leaves rings of pitting around the bore at whatever height the piston was sitting and also sometime damage to valve seats. Occasionally there is evidence of water bubbling up the central stud where the gaskets get hottest and are under most stress, other times nothing until the engine is stripped for a valve grind or other work. This is a new one for me, I have still to come up with a conclusive answer, gaskets have changed we no longer get Payen, and I am not lapping heads but having them ground. I would immediately suspect the latter if it were not for the fact that other engines have exhibited the same issues where they have not been through my hands.