89 model 150 xr4 Merc, was running just fine down the lake then all of a sudden locked up? Any ideas? im pretty motor savvy but not to much on the internals? Im thinking rod? But what would cause it?

could be the driveshaft, could be a number of different things , Sounds like the gearcase is fine. Did you mix oil with the gasoline, or does the motor have a functioning oil injection system? Remove spark plugs and spray motor with penetrating oil. Maybe she will unseize.Are you trying to turn flywheel by hand?or is starter not engaging?Did you blow bluish smoke? 

 

yes has oil injection and it is working, i tried to turn by hand and with starter goes around so far and stops.. 

 

Sounds like a connecting rod to me if it was seized and you got it loose it wouldn't stop partways. Something caused it to seize maybe it stopped pumping oil or maybe the water pump sucked something in.

Had that happen to me on an '87 XR2.  Forgot to hook up the 3-gal remote oil tank.  Even though the tank on top of the engine was full, without the remote tank connected the system didn't pressurize.  Locked up running across the south end of Okeechobee.  Toasted the whole powerhead...

Sheew thanks guys