Low compression / oil from breather

[cwalsh]

Hello all - I’ve done a search on the forum but couldn’t fund much info pertaining to my specific problem.

Took the boat out last weekend for some night fishing (3.0l OMC) and on the way back to the marina it started running rather bad, shut her down and noticed that oil was coming out of the valve cover breather (not horribly bad, but enough to cause a concern) after I started her back up she would just bog down and die if I tried to gun it under a load, but if I put the boat in N and gave it some gas it would rev up just fine.

Got it home and did a compression test the next day and from cyl1 down it was 110,110,75,50 :facepalm: I am kind of lost on what could be wrong, I just did new pistons and rings going on four years ago and there are not many hours at all on the motor after the rebuild so I can’t see the issue being bad rings. I squirted some oil into the cylinders and re-did the compression test and the numbers stayed the exact same, no change.

Now I have been told that being two adjacent cylinders and the compression being low that it could possibly be a head gasket leak between the two cylinders?

Just looking for some thoughts before I tear into it.

Thank you.

 

[Maclin]

Re: Low compression / oil from breather

I think I would remove the head and take a look. You could do a cylinder leakdown test on each cylinder to see if it is valves, pistons, or gaskets, but in almost any case you will need to remove the head anyway to begin fixing so I would do that.

 

[Bondo]

Re: Low compression / oil from breather

Hello all - I’ve done a search on the forum but couldn’t fund much info pertaining to my specific problem.

Took the boat out last weekend for some night fishing (3.0l OMC) and on the way back to the marina it started running rather bad, shut her down and noticed that oil was coming out of the valve cover breather (not horribly bad, but enough to cause a concern) after I started her back up she would just bog down and die if I tried to gun it under a load, but if I put the boat in N and gave it some gas it would rev up just fine.

Got it home and did a compression test the next day and from cyl1 down it was 110,110,75,50 :facepalm: I am kind of lost on what could be wrong, I just did new pistons and rings going on four years ago and there are not many hours at all on the motor after the rebuild so I can’t see the issue being bad rings. I squirted some oil into the cylinders and re-did the compression test and the numbers stayed the exact same, no change.

Now I have been told that being two adjacent cylinders and the compression being low that it could possibly be a head gasket leak between the two cylinders?

Just looking for some thoughts before I tear into it.

Thank you.

Ayuh,.... Pull the head, 'n Look.... I'm guessin' either the head gasket, or Detonation ate the pistons,...

Or Both....