[KGBnut]

I'm a recent convert to the leak-down test. As alexiskai said, it will tell you not only IF there is a leak, but WHERE it is and how bad it is before you take anything apart.

You test the cylinders one at a time, on the compression stroke and listen for the hiss. If you hear it through the carb: it's the intake valve; through the exhaust: an exhaust valve; oil filler: rings; bubbles in the radiator: head gasket.

It is not a perfect system. You can get confusing results if, for instance, the head gasket is leaking between two cylinders. However, it is a lot of information before any major wrenching.

I built my own leak-down test kit with parts from Harbor Freight for about $25.

Ken