This is a 1983 Johnson 35 (J35ELCTS) that belongs to my 80 year old neighbor. I offered to help, thought I could fix it but I'm stumped now. Started out with engine not running reliably and shutting off. I discovered a bad water pump impeller and replaced it. Assuming it overheated, I checked compression and found the top cylinder to be 150, bottom was 100. I pulled the head and replaced blown head gasket. Inspected cylinders wall for cracks but didn't find any. Engine starts and runs pretty good now but wants to overheat. Water comes out exhaust fine but no water from pee hole. I can feel a little air from pee hole though when running. It seems as if the bottom of engine runs cool but top gets hot. An IR thermometer will indicate the bottom half of cylinder head at about 140* and the top will get to 200 before the alarm goes off. I pulled the plugs and check the compression again and got 150/150. I then tried some compressed air into the pee hole fitting and air bubbles come out from water pump inlet as expected.. However, since I still had the spark plugs out, I could also hear air escaping from a spark plug hole. If I turned the flywheel by hand, the escaping air would change between the two cylinders. If I turned the fly wheel so both pistons were half way in the cylinder, I couldn't hear or feel any air escaping from spark plug holes.
I'm thinking that there is a leak between the crankcase or exhaust and the water jacket?. Where to look for this leak? Any help would be sincerely appreciated.
I'm thinking that there is a leak between the crankcase or exhaust and the water jacket?. Where to look for this leak? Any help would be sincerely appreciated.
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