Rotax 657 with Broken Wrist Pin or Separated Piston

[randomguy]

Ok, some of you (especially Dr. Honda and wabbit1211) have been following a thread to diagnose my engine issues. (Thanks a TON btw.....) I've now pulled the engine all the way out and have spent some quality time with it.

I took the head off while still in the boat and watched the tops of the pistons move. Not much to be seen there. Now that I've gotten it out, I took the intake assembly off as one big sub-assembly. I've now been manually cranking the FW and watching through the intake holes.

And it's not good news. One of the pistons appears to have separated. The head is moving from above, but when looking through the intake hole, the skirt is stationary and I'm assuming galled in the bore. So I suppose that there's a possibility that the conn rod is still good, but I'm not sure at this point.

So here's my question. Should I assume that I *may* be able to get away with a top end kit and disassemble from the top side? Or should I give in and just tear into it from the bottom?

I guess I'm kinda hoping that I could get away with a top end kit and leave the crankcase in one piece. Anyone think this is a bad assumption or should I just proceed with a top side tear down and see what happens?

 

[Dr Honda]

if the bottom is original... I would just bite the bullet, and do a full rebuild. If you do a top end, the crank may let go in a short amount of time.

BUT..............

Ge the jugs off, and remove the pistons, and see how smooth the crank rotates. Any rough spots, or movement on the rod bearings... and don't chance it.

 

[randomguy]

Great advice, thx again. Jugs are off. Mag side con rod is bent. How the crap does that happen? So actually I was wrong, the piston appears ok. I was seeing the back side of the sleeve, not the piston.....

So apparently now the crankcase will def have to be opened. I'm obviously in for at least a con rod. What else? To be honest, I've got $1200 in this boat and trailer. However, I work at a machine shop and have access to a static balancer and V blocks and indicators and stuff. Should take the crank out and check for runout and then see what it looks like?

Should I buy a rebuilt engine and put it in? Should I quit and part this thing out and try to sell the trailer? Man, what a pain in the a$$.