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Yamaha 150 four stroke (Twins) running hot

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military369

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Hello and thank you up front for any advise I receive.

My father has Twin Yamaha 150 four strokes that are running hotter than they should. The temp runs right in the middle, half way mark at 3,000 rpm. Once you go to 4,000 rpm the temp goes to 3/4 and jumps a 1/4 in the guage. Both guages are reading the same temps. Both motors have been fully serviced, new impellers, plugs, thermostats, complete job, big job. I believe the two guys performing the work were there for 8 hours doing the full maintainance. The motors have right around 130 hours on them. Also, this problem did this same thing before the maintainance.


Any help and advise would be greatful.
 
OK, it's happening in the water off the trailer. Are the alarms sounding or are your gauges just showing high temp? Gauges may be reading incorrectly if no alarm is sounding.
 
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military369 said:
The alarms are Not sounding, just the guages are showing high and only at 4000 rpm. 3000 rpm the guages read right in the middle. The boat is on a boat dock in the back yard, no trailer, its on a lift.
Click to expand...

Not to mention, the engines are not in the red they are getting to 3/4 on the guages, seems a bit too high on the guages. Thats why the alarms are not going off.
 
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Get an IR temp gun. You can get one at Sears. Shoot the temp of the engines while they are running. If the alarms are not sounding, I would say you do not have a problem. That engine is computer controlled and if there was a problem it would be tripping an alarm and shutting the engine down.

Are the temp gauges new or old?
 
If this is the norm then I thank you for all of your time and your effort you put into this, you have been great! I think the IR temp gun is a great, saftey idea. Thank you again.
 
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