The Stovebolt Site Forums The Shop Area Engine Shop overheating damage found - what to do now?

If you want to really find out where your compression is going to make yourself an adapter to inject compressed air into the cylinder, I made mine by dismantling a sparkplug, take ceramic out and grind smooth just above the hex head, knock out everything in the center, grind the little tip off the end. Weld or braze a female pipe adapter on to the hex head and screw a quick disconnect into it. This will allow you you to connect it easily to your air system. Get your #5 cylinder to the top dead center and lock it in place, in your case you could probably just put it in low gear. Turn the air on with about 30 psi and listen for air leakage, if it's the exhaust valve it will come out the tail pipe, if it's an intake valve it wil be heard in th carb, if it's rings it will blow into the crankcase and you'll hear it at the vent, if it's head gasket it may blow out the side, I'm not sure exactly on that one. On aircraft we use 80 psi, so if you don't hear it up the air pressure. Hope that helps, at least you will know exactly where and what your problem is with out pulling the head. Dave