150 yamaha twins, rt engine keeps failing

[pine island fred]

good friend has a pair of 150 2 strokes, 2000 models. left eng. fine ,rt eng. on its 3 rd or 4th. powerhead,under extend warrenty. eng. failed again ??? mentioned to me that he flushes both motors at the same time ( not running ) and the engine that fails always has much less water flow spilling out the leg. question. is it possible that the wrong , mismatched, defective, incorrectly installed gasket is being installed when the power heads are swapped out. dealer has been good addressing the problem, but the power head needs zippers now. same mech. at dealer does the work. any ideas appreciated. regards fred

 

[pine island fred]

Re: 150 yamaha twins, rt engine keeps failing

would like to add that motors are low time and not abused. water out of witness holes are the same but that just shows the exhaust is cooling . last new head had all accessories and computer replaced. still has original problem. my last suggestion was for him to find jose and carlos to take it one way to cuba, but at this rate the boat would not make it.

 

[Ray Neudecker]

Re: 150 yamaha twins, rt engine keeps failing

A close examination of the failed motor and pistons should lead you to the cause of the failure. Most failures are related to either fuel restrictions or oiling restrictions. In theory water heating problems should kick off the alarm before failure. If all accessories replaced included carb rebuilds and replacement of the valves in the oiling system and fuel pump, then a fuel restriction between the engine and fuel tank would be the first thing to check. Did the crank or rod bearing go down or did the piston or pistons sieze?

 

[pine island fred]

Re: 150 yamaha twins, rt engine keeps failing

i never saw the engine apart but believe it is always nbr 6 piston that burns/seizes. high temp warning has gone off occasionally after extended periods of idle. never at off idle. shuts motor off and problem goes away on restart. believe this engine is injected but not sure. could the over temp. warning sensor be installed on the cyl. bank that is not nbr 6 cylinder side ? thanks fred. also gulf water temps are well above 90 this time of year