1984 Mariner 9.9C Factory Compression

[cchildr84]

I have a 1984 Mariner 9.9C motor Serial #682C-049356. It has great compression; even at 120psi in both cylinders. I don't have manual for this book, so I was curious if anyone new what the factory compression was. Is 120psi what it was from the factory. Just a question out of curiosity. Your help is appreciated.

 

[Texasmark]

Don't know but in my 90 hp service manual, 120psig was the top of the mountain.......Ok on the high side, MAY have problems below. A lot can affect your compression. Most learned folks rely on cylinder balance rather than an absolute number for that reason.

 

[cchildr84]

I guess I'm not really following your comment above. I'm not having any issues with this motor what so ever. It's one of the best motors I've ever had. I was just curious how those numbers compared to factory numbers. It probably doesn't have 20-30 hours on it. I know since around 1994 my family nor my self have probably not even put 10-15 hours on it. It runs great and starts on the first pull every time.

 

[Texasmark]

Might consult the factory. Might get an answer.