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1994 120hp Force motor rebuild?

J

JM10902

New member
I have a 1994 120 force that had a leak in the exhaust gasket that allowed water in the 1st cylinder. There is some scoring on that piston and I am not sure how I should go about either fixing the motor or just finding something else. Any suggestions?
 
Re: 120 Force motor rebuild?

JM1092, I now suspect I have a similar problem with my 1996 Merc sportjet 120 (force powerhead). I thought it was flooding but when I took it out a second time, exhaust gases blew out of the no 1 cylinder when I removed the spark plug. I did not notice any water in the cylinder so I suspected a reed valve problem. The reed valves looked good. The first time I took it out it ran great initially for 15 minutes and when I powered back to idle it died. Couldn't get it restarted. The temperature didn't go above 150 degrees the whole time so I don't suspect a crack. I guess I'll have to check the exhaust gasket now. Any suggestions ?
 
Re: 120 Force motor rebuild?

JM10902, since you've already torn down your motor to get to the exhaust gasket, were there any tips that might help me when I do the same on my powerhead.
 
Re: 120 Force motor rebuild?

I actually didn't tear it down myself. I had a person who repairs motors do it. Sorry I can't help.
 
Re: 120 Force motor rebuild?

I initally thought that the the exhaust plate or cylinder may have cracked but it ran well for 15 minutes without the cylinder temperature exceeding 150 degrees F. I was very careful of the temperature as it had been sitting for a couple years. It was running great until I throttled back to idle and it died. I guess I won't know until I get into it. I understand a cracked exhaust plate is not uncommon with this engine.
 
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