Sum of all Fears! Broken Rod(s)?

[parsleap]

Bad day on the water yesterday. Running 1993 Yamaha 150 ProV up to full throttle (first time boat has been fired up in two years). At around 43 mph, 5100 rpm, engine started to lose power and commenced an awful rattle sound. In a matter of a few seconds, the engine quit and locked up - starter couldn't budge it. On land again, when in gear, cannot budge prop. I've never had an engine break a rod or rods, but I imagine this is what has happened. A little background is that two years ago my brother in law used this boat, and despite my telling him all the parameters within which to operate the boat, he bragged later that the boat did 65 mph. The problem is that this boat only does about 48 mph tops! I think he was running the thing at 6500 rpms, but because of the dash readout, thought he was running 65 mph. Lord only knows how long he ran it at 6500 rpm. I did trim it up a bit too high yesterday, and hit about 6100 rpm, but very quickly brought the prop back down and settled at about 5100. Anyway, just trying to confirm what I'm afraid has happened. Anyone ever broken rod(s) and seized up a motor? Any comments on expected repair costs (i'm afraid to ask). Any good alternative solutions in fixing/replacing?

Distraught!

 

[99yam40]

Re: Sum of all Fears! Broken Rod(s)?

lean fuel will melt pistons and not enough oil will get the bearings is what I understand. with it sitting for 2 years, I would lean towards the lean fuel burn. But who really knows until you tear it down and see what happened and how much the repair is going to be. don't forget to fix what caused it to do what it did.
Loaning your hole in the water you throw money into, to anyone is never a good idea but I donot know if it had anything to do with it seizing.

 

[parsleap]

Re: Sum of all Fears! Broken Rod(s)?

I thought about the lean fuel problem, and that could be it. Like you said, just have to tear it down (or pay someone hansomely to do so) to find out. The motor has auto oil injection, and had plenty of 2-stroke oil. I had started and idled the boat early that morning for 20 minutes or so, and had made one short run at 2/3 throttle without problem. It's possible that the oil pump crapped out, but it was at least seeming to work earlier in the day (good smoke in the exhaust at idle).

 

[99yam40]

Re: Sum of all Fears! Broken Rod(s)?

the pumps usually do not go bad something plugs up. filter.lines.check valve, etc.
Pop the heads and have a look see, maybe only one piston.

 

[Trent]

Re: Sum of all Fears! Broken Rod(s)?

How about dropping your lower unit and see if thats why it is locked up first?? Check the easy stuff first. Pull the plugs and look at them. Any damage to the sparkplugs?