25 hp Mercury compression

[terryneal]

I recentaly took my 25 hp mercury motor in for a tune up. They said my compression was 120 psi and said it needed to be rebuilt. I was wondering if it realy does need to be rebulit or not? Also, what should the compression be?<br />Serial number: 5805206 (not sure on the year)

 

[Hooty]

Re: 25 hp Mercury compression

Your engine is a 1980-81 model. <br />There are no factory compression specs.<br />If the engine needs rebuilding, it's not because of the compression. Testing compression is a means to compare one cylinder to the other. If the difference between the highest compression of one cylinder and the lowest of another is no more then 10% the engine is good to go. <br /><br />c/6<br /><br />Hooty