1990 70hp yamaha lack of compression

Joined
Jan 7, 2007
Messages
2
There is a compression reading of 75 on CYL 1 and 2
Then a reading of 15 on CYL 3. Without getting to involved with this engine, i would like to know if anyone might have an idea, of what would be the cause of something like this. This unit has been use in Salt water only.I was told that this engine was beggining to overheat, just before they shut it down, and never used it again, (end of this summer). I just purchased this unit with this problem. I took the cover off, where I could see the top of the piston, and checked the walls carfully(all 3) and no apparent scratches,of gauges.Some ideas would be appreciated,as to what I should look for.Thank you, Ed 8)
 

JUSTINTIME

Captain
Joined
Sep 2, 2006
Messages
3,284
Re: 1990 70hp yamaha lack of compression

head gasket
maybe need new rings

have u put a new head gasket on and checked compression?
 
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