low compression

[hl]

first time this year to use a boat and found the engine seemed lock-up. He said it ran perfect the last time out last summer. This is a 1992 70 hp. We sprayed some oil in all 3 cylinders and got the engine to come lose. The compression was from top to bottom - 120 , 60, 120. We did not attempt to crank the motor. Is this motor shot or can anything be done outside of a rebuild?

 

[racerone]

Fairly common for the # 2 cylinder to have issues.--------Remove cylinder head and have a look in there.-------Likely a scored cylinder / piston is the issue.

 

[Bosunsmate]

As above, might be lucky and just a head gasket gone is the issue

 

[hl]

Would a bad head gasket cause the lock-up?

 

[Bosunsmate]

Would a bad head gasket cause the lock-up?

Nope but, many motors that are left sitting an are not winterised will have a lock up when tried to start up in a few months and have nothing permanently wrong with them.So the lockup might be just incidental.
Seems unfortunately like you forgot the first rule of buying a motor- check compression yourself:frusty:

 

[jimmbo]

deleted

 

[emdsapmgr]

If the head gasket were leaking, water could get into that middle cyl. That could cause a hydraulic lock.