Help powerhead explosion 1990 Mariner 200 hp

" Dear all,

I need some h

" Dear all,

I need some help and advice. About 3 weeks ago my 1990 Mariner 200 HP developed a crack in the powerhead (I think this is right - the metal casing that the houses the cylinders and pistons) such that it couldn't be sleeved and had to be rebuilt - or so I was told. I had the entire thing replaced replete with new carburators (3), gaskets, 2 new pistons etc. The powerhead itself came from a used engine. The mechanic found the part and rebuilt the engine. We tested it together running the engine for an hour. It was fine. Yesterday, I took it out for the first time and ran it. About 1 hour in, it suddenly began to make a loud cranking noise and about 3 seconds later simply died. When I opened it up, I was shocked to see the entire powerhead my the top left cylinder had burst apart, the rods had been thrown along with about half of the engine. The mechanic has basically said to me "that is the way the cookie crumbles. Probably some contamination in the gas tank that lead to over compression in the cylinder causing it to explode." Is this a viable reason? What should I do. PLease help!!! Is my engine dead? "

No such thing as over compres

No such thing as over compression in a cylinder. I think somebody made a mistake assembling parts that spin at 5000RPM.

" Thanks, Sparky, can you thin

" Thanks, Sparky, can you think of any reason the whole thing would blow apart like that? - I mean I have never seen anything like it before, the whole top left cylinder casing was simply destroyed. Could there have been small fractures in the used powerhead installed? What do you think? "

I cannot say without the part

I cannot say without the parts in front of me.Take the motor apart and examine the parts.The cause will likely show up .Cracks in parts that have been there for a while are "dirty" .Cracks that result from a catastrophic failure would be "clean".A fatigue crack is usually dirty for part of it and clean for where it finally let go.

" Thanks sparky, I will do so.

" Thanks sparky, I will do so. Should be pretty easy as it is already blown apart. "

Hey i had the exact same prob

Hey i had the exact same problem with a 120 force engine. After the rebuild about 10 hours of running it came apart. Threw a rod thru the block. I decided to take it to another mechanic and after he tore it apart he found that some roller bearings were missing. He concluded that they were left out during the rebuild. The original mechanic said there was nothing he could do about it. I spoke with an attorney and all i could do was to report him to the BBB. I did that and also painted big lemons on the cowl and paid the business across the road a few dollars to place the motor there. Had a sign to contact me if they wanted to get a motor repaired. After a week the mechanic agreed to refund half the cost he charged me.