1970 mercury 115hp comression question

Isaacm1986

Isaacm1986

Lieutenant Junior Grade
Joined
May 20, 2009
Messages
1,086
So i have a 1970-71 mercury 115 hp, the motor runs good, we got everything working on it, did a compression test this morning and 5 cylinders are at 150psi, but the top cylinder (6th cylinder) is only 90psi. what does this mean? is it ok to still use the motor? any thoughts would be helpful.

thanks
 
achris

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Re: 1970 mercury 115hp comression question

This means that there is something wrong with the top cylinder. If you keep running the engine you risk further damage, depending on what is wrong.

Chris.......
 
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