low compression

[gary giummule]

I just pulled my exaust manifolds as the engine was overheating. I used a temp gun in different locations on top of the engine and got readings well above 200. My gauge on the boat showed a normal 160. While I had easy access I ran a compression check with a new compression gauge and got low readings between 45 and 55 psi. The boat seems to run strong till I noticed one riser much cooler than the other. Do I need to recheck compression when engine is warm? Doesn't seem the engine would hardly run with readings so low. Any help would be appreciated. I have a 1986 volvo 225 engine.