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Low to no compression on #3 cylinder

J

jetpc4

New member
"I have an early 70's merc

"I have an early 70's mercury 85 horse. I just bought it, so dont know a whole lot about the history, but the motor seems to be really clean. i pulled the spark plugs and did a finger check on the compression and the #3 cylinder has very little if not zero. Whats the next step? totally tear down? or is there any other trouble shooting ideas you may have?"
 
"you can remove the side cover

"you can remove the side cover to have a look at the cyl itself. If its not scored then you can decide for yourself if its worth fixing. If you think the rings are broken you can take a small screwdriver and push on the ring, it should spring back. You also need to check for a hole in the head, or crack. These engines are made without a head and cast as one piece. They just have a water jacket cover. Sounds like too much work."
 
"As a guess, the rings are &#3

"As a guess, the rings are "welded" in the piston grooves. (Seen this before.) Only cure is a new piston and rings and a hone job--at the least.

Sorry.

Jeff"
 
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