1990 70hp merc no compression

[pete s]

My wife surprised me Father's Day with a boat sitting in the driveway. That's the good part. While out today it was hard starting and would not stay running, that's the bad. Could hear uneaven compression when it was cranking, pulled plugs and found middle cyl to have 0 compression.
Whith that said how are these poweheads to rebuild/re ring? I'm an automotive tech so not completely green however I have not rebuilt a large outboard before. Any advice greatly appreciated.

 

[flyingscott]

What is the serial #. I am pretty sure the motor is a blind bore so you will need to find a machine shop capable of boring it. The rebuild kit is available for a reasonable price. As long as everything is in good shape and do the labor yourself $800-$900 dollars should cover it. If something is really wrong with it you may want to replace it.

 

[pete s]

S/N is 0B110490. Looked in cyl with bore scope found top of piston/upper ring land to be gone in a small spot. Oddly enough the cyl wall looks like no gouges (probably wishful thinking on my part). Found machine shop to bore block for 250.

 

[flyingscott]

Your motor is a 1987 model

70

1987

ELPTO

B110054 - B240450

A722297

 

[pete s]

Thank you! I was just about to post I can't find the S/N anywhere. When doing rebuild anything to watch or look for? Or is it pretty straight forward.

 

[flyingscott]

Make sure the sleeves are still in place. Find a good machine shop that is familiar with those motors as you will likely have to bore it.

 

[Mercurylips]

No Title

Thank you! I was just about to post I can't find the S/N anywhere. When doing rebuild anything to watch or look for? Or is it pretty straight forward.

Try looking here for your number

 

[flyingscott]

Try looking here for your number

Serial # is in post #3. I think he meant he could not find the year using it.