why did my 90 hp yamaha blow up??????

[redbull660]

I have a 1994 yamaha outboard 2 stroke jet on my 94 hewes craft. Last year it quit running. It would run fine and then just shut off, It did this 3 times so I put it on the traler and did a compresion test and one cylinder was way down to only 10 pounds of compression. I have recently ordered a new powerhead threw Iboats, but am concerned on why this happened. I have been talking to a guy and he says that It should not be the oil pump because it runs off of a gear on the crank shaft. Before it quit it would run fine and then shut off like it ran out of gas. <br /><br />I did take the head off and found that there was a lot of corrosion inside of the water jackets. Do you think maybe it got to hot. Thanks, any info would be greatly appreciated.

 

[rodbolt]

Re: why did my 90 hp yamaha blow up??????

hello<br /> before installing your new powerhead rebuild the carbs. a leanout can cause piston failure,replace the fuel pump. bad pumps,and yes they do go bad, can take out pistons. clean the oil tank and lines. test or replace the checkvalves. replace the water pump. <br /> pictures of the piston may help ID the cause of failure. when was the last test of the alarm system?<br />also test your overheat sensor.<br /> most powerhead failures are caused by the failure of another subsystem. all work or the mule quits.

 

[bigbrownbuku]

Re: why did my 90 hp yamaha blow up??????

i would go with replacing the oil line checks and the oil pump. its cheap piece of mind. also recondition your waterpump.

 

[redbull660]

Re: why did my 90 hp yamaha blow up??????

I just ordered a new oil pump, water pump, water pump impeller, carb kits and a fuel pump. When I get this done it should be good as new. Thanks guys

 

[Yepblaze]

Re: why did my 90 hp yamaha blow up??????

Make sure you get the carbs all equally operative, as this might be suspect of the source for the catastrophic failure. <br /><br />Or it will happen again. <br /><br />If your motor was 100% when you got it, you should have noticed the day when it just didn't run like it was. That should have been the clue to things that followed.<br /><br />Also if applicable, confirm ignition timing is within spec.