1989 Force 85HP Low Compression of Cyc #3

I have a 1989 Force 85HP that

I have a 1989 Force 85HP that just started running poorly. Last week I added a can of Seafoam and filled the tank with fresh gas and oil. Engine was purring along nicely while trolling about 4mph. After about an hour I noticed a slight change and the engine was running slightly rougher. About 30 min later I put the motor in neutral and it died - very unusual for this motor. It would restart but die as soon as I tried to put into fwd or rev. Spark appears good on all cyclinders but the compression on #3 is only 40 psi (105 psi on #1 and #2). Comments? Suggestions?

"your engine is destroyed. Wi

"your engine is destroyed. With only 40 psi in one cyl it will never run. all cylinders have to be over 100 and with in 10% psi of eachother. you may just have a stuck ring if you're lucky. try putting a few drops of a heavy motor oil in the number 3 and run it, on land with muffs. that may build you some compression back up if its just scored. good luck!"

"I put a couple of squirts of

"I put a couple of squirts of 30wt oil in the cylinder. Compression jumped way up to 55psi!! It does run but it's hard to start and there is an intermittent miss. I've got an appointment at a repair shop to bring it in next Friday. Their guess over the phone was a complete rebuild, estimated at $1500-$2000."

yeah it'll never run like

yeah it'll never run like that. sounds like you may have a cracked or chipped piston or ring. for that much money you could about buy a whole engine. good luck

"The comment about the engine

"The comment about the engine being destroyed is opinion.

Certainly it's in trouble, but until it gets opened up, the range of problems is conjecture not fact.

Yes, we could be talking about blown pistons, rings etc or maybe something as esoteric as a cracked bore. All have different levels of effort to repair.

Before taking it in, double check to make sure you're not dealing with something as simple as a blown head gasket."

I pulled the head off Friday e

I pulled the head off Friday evening hoping the problem was the head gasket. No such luck. The gasket is very good but there are significant dings and dents in the top of the piston and cylinder head of cylinder #3. Lots of carbon on top of the piston. There's some cylinder wall scoring in a couple spots. There's also a small spot (1/8" dia) on the edge of the piston top that looks like it's extruded up - like a piece of a ring broke off and squeezed between the cylinder wall and the piston. Cylinders #1 and #2 are nearly perfect.

Easy motor to get a hold of...

Easy motor to get a hold of.... Buy one and keep the old one for parts. Cheap way to get back in the game.