A couple months ago after acquiring this boat (1986 Winner Escape 17'), I took compression readings on all four cylinders after warming up the engine. #1-130, #2-118, #3-115, #4-70 (all in psi). After squirting some oil into the #4 cylinder, it went up to 90 psi. Motor has not idled very well since I got it. Now is worse. Checked compression today: #1-130, #2-110, #3-110, #4-25 (squirting oil into cylinder did not improve reading). I have not performed a leak-down test yet. No water in oil and oil still looks good (changed it when I got the boat in March with Quicksilver part synthetic 25W-40). No oil usage after ~10+ hrs of running. Seems to use a lot of gas. 140F thermostat (new in April) and runs at 165F max, but never at 140F. Plugs look good except the #4 not as clean as the others and slightly sooty but not oil soaked. Runs very good above 1200 or so RPMs, but doesn't seems to lack power. I have not run it above 3200 RPM. I am ready to remove the head, and am hoping it's a bad head gasket and/or valve issues.
Any thoughts or recommendations?
Will I cause more damage to the block or head if I continue to run it?
Any thoughts or recommendations?
Will I cause more damage to the block or head if I continue to run it?