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Mercury 125 died under power

R

reeltimeray

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I have a 2000 Mercury 125 s/n

I have a 2000 Mercury 125 s/n OTO87957. I spent all day on the lake fishing in 15 to 20 MPH winds and 3 foot swells. At the end of the day we were headed away from one dock going to the take out. After leaving the no wake zone we started to bring the boat to plane and it seemed sluggish so I pushed the throttle all the way. Just after that the motor quit. I tried to restart the motor and it would only kind-of run with the choke in. At that point I quit trying to run the motor. I got the boat home and pulled the spark plugs and the bottom cylinder squirted water out. I looked at this site and it looked like I might have a gasket problem. I checked the compression and the bottom two cylineders had 135 and the third had 130. The top cylinder had zero (yes zero) I squirted oil in the cylinder and still zero. What is the next step?
 
"power head let go. Pull the s

"power head let go. Pull the side cover off the exhaust, look into the cylinders. sleeve's popped?"
 
"Sorry, sounds major. Any pis

"Sorry, sounds major. Any piston or ring chunks floating around inside. Pull the head off as well, so you can see all the damage....hopefully the crank is ok."
 
Thank you for all the advice.

Thank you for all the advice. I pulled the cover off around the spark plugs and found 1/3 of the cylinder missing. It came off in one piece so I don't think there alot of metal in the engine. Does anyone know what could have caused this failure?
 
"Not sure where the chunk came

"Not sure where the chunk came from...piston? cylinder liner? block? 1/3 of a piston or cylinder is going to leave some serious scaring, bent rods etc...any metal in the engine will take out roller bearings and more than likely end up wedged between pistins and clyinders doing more damage. If engine is salvageble at all it had to be taken completly apart now."
 
"here is a picture. Any ideas

"here is a picture. Any ideas? Yea it's totaled.
249779.jpg
Engine
 
"Wow, seesm starnge that the p

"Wow, seesm starnge that the piston loks relatively unscathed. First guess would be a casting flaw in the head. Fatigued and let go? The lower edge of the part missing (by the piston top) looks very straight/even following the top of the piston. Or it gulped enough water and hydrauliced causing it to let go. When you get the rods out where you can sede them I would expect that one to be bent if that is the case."
 
When you look at the missing p

When you look at the missing piece you can see carbon on some of the break so it's not like a hydrolic lock and busted all at once. If you look at the other cylinder you can see a crack forming in the same place. At this point I'm thinking about just going with a rebuilt unit. I don't even know where to start looking for a block. If I did find a block compared to a car or truck motor how difficult is it to rebuild?
 
"It is possible it got realy h

"It is possible it got realy hot at some point and then was restarted to soon, cold water shock on hot metal resulting in a crack which then let go sometime later. Could be why the coating on the head looks like it is flaking off on both heads shown. Look at the crank for any damage before you decide what way to go."
 
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