yamaha 150 runs hot at idle speed

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bruster

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I have a 1991 150 horse yamaha outboard. The engine runs great above 1700 RPMS, any lower and it runs hot. I have replaced water pump, both thermostats still runs hot at idle. Any help would greatly appreciated. Bruster
 
SparkieBoat

SparkieBoat

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Re: yamaha 150 runs hot at idle speed

sounds like you may be losing water pressure at your pump maybe..check the seals..also make sure you installed the impeller with the fins turned the correct way.
 
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99yam40

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Re: yamaha 150 runs hot at idle speed

Check the PRV (pressure relief valve) it is probably stuck open
 
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bruster

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Re: yamaha 150 runs hot at idle speed

Hello thanks for the info, I hate to sound stupid but where is the PRV located on 1991,150 horse Yamaha. Bruster
 
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bruster

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Re: yamaha 150 runs hot at idle speed

Thanks to all that helped me with problem. I removed PRV and I think it is the problem, lots of sand and gunk. New part won't be here until next week. Thanks to all and I would reccomend this site to anyone. Bruster
 
SparkieBoat

SparkieBoat

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Re: yamaha 150 runs hot at idle speed

99yam40 is a top notch guy..he has helped a lot of people including me. I know we are all appreciative.
 
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99yam40

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Re: yamaha 150 runs hot at idle speed

I just read these post a lot and am able to remember some of what have read.
Sure wish Rodbolt was still hanging around to answer questions. That was a man full of information.

Bruster, be careful pulling the grommet out and cleaning up every thing. Some have lost the rubber grommet inside the motor, which can block cooling
 
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