Triumphrat

pinhead

I have a 68 t120 engine that seems to be leaking oil from the head gasket on both sides at the back of the cylinders near the pushrod tube. I still have good compression on both the combustion chambers (over 120psi). My question is, since this is my first triumph build, is this a normal leak? Is it the head gasket leaking or the top of the pushrod tube?

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If it isn't pinstriped, it's not done.

jimmy bush

There is no oil passage through the head gasket. It is probably coming from the push rod tube. Second choice would be the rocker box gasket. If they leak, there is a possibility the oil is seeping into the head bolt hole and coming out the head gasket but that is a very remote possibility.

slicktero

Oil seeping down a head bolt and then coming out at the head gasket surface is not as remote as Jimmy Bush may think. I have been repairing Brit bikes for 39 years, and oil coming down the head bolts is common. Usually two things cause this: 1) The head has been milled considerably in the past. To the point that the original pushrod tube orings are actually now too thick and causing a certain amount of bowing of the head . 2) Cheap rocker box gaskets that do not have proper wire reinforcing. Watch out for wire reinforced gaskets that are thick, they are about as bad as non-reinforced gaskets. I always use thin wire reinforced gaskets, or solid copper rocker box gaskets, and coat both sides of the gaskets with Three Bond gasket sealer. This always works for me. I hate having to warranty oil leaks, but doing the rocker gaskets this way, I rarely, if ever, get a leaker these days.