I don't seem to be having much luck in my restoration project on the LX565. I recently noticed air bubbles (about 3 bubbles a second) in the coolant overflow tank. No sign of water in the oil or any other problems though. I'm assuming this is a head gasket gone?? The engine is not the original Shibaura but a 2.2 liter Perkins which looks almost identical to the 2 liter Shibaura. I cant say for sure but I think the engine is about 13 years old. Is the head gasket a common problem with these engines and a likely cause of the air bubbles? I'm annoyed I didn't see the problem when I tested the engine before I bought it. The bubbles aren't always visible, but seem to be there when the engine is fully warmed up.