Dodgy Head Gaskets

Recently reconned an 850 RH10 head, and fitted a no brand name copper flame ring composite gasket. This all went fine up to the 3rd torque up when unexpectedly, it blew on the right hand side just on starting it up.

On removing it, whilst undoing the head bolts, the one on the right rear had a unusual slack - tight - slack sensation which I seemed to recollect had also occured when we first fitted the head. On removing the head, the gasket was not so much blown as torn! This was adjacent to the right rear head bolt and on closer inspection, it was oval not round, and almost all others exhibited out of round. What has happened is that this gasket did not have perfectly aligned bolt holes and the worst one had the head of the bolt chew into the edge of gasket as we fitted it.

The replacement was a different type, plain steel flame ring composite and we fitted it to the cylinder deck first with all bolts just to ensure it was accurate and no possible overlap. It was good, but again these aftermarket no name products are a concern. Its worth doing a dry fit and checking the accuracy of the gasket simply to avoid this extra work and disappointment.

Mick

ML, I had bad no-name head gasket too (850 w/RH10). It had narrow copper flame rings. But the flame rings were too small and nearly "bridged" the combustion chambers. The rest of the die cut openings were too big. Also, it was assymetrical. The tool that punched it out must have been very dull because the edges were ragged and deformed (photo attached). I was scared to use it, so I got a good one!