1992 75HP Warning Buzzer

I have 92 75hp merc, while out on the water this weekend there was some debris floating around from the recent rains. Motor rain fine all morning then later in the day the over heating buzzer sounded. At an Idle there is a steady stream coming out the back and the buzzer sounds. Once up to 30 mph the buzzer goes off, then slow down at the dock and the buzzer comes back on..

Next day I run it with a flusher on it the driveway, buzzer sounds as soon as it starts up then goes off. I let the motor run for 10 minutes at idle and at up to 1500 rpm's with a steady stream coming up the back (noticed some water coming out the shift linkage hole, not sure if its suppose to) in all of the 10 minutes of running on the flusher the buzzer never came on after the initial start up for 2 seconds. Was the water from the hose putting enough pressure up in the impeller to act like when I was at crusing speed?

Is the sensor bad?

Did I pick up some debris in the water intake & now its gone?

Is the impeller bad?

Thanks for any help.

Re: 1992 75HP Warning Buzzer

Ok took the boat on the water last night.

Sat at the dock idling for 10 minutes with no buzz, keep my hand on the motor didn't seem hot. A few more minutes the warning buzzer came on. The motor still didn't seem to hot to the hand, put the boat in gear and started moving at a slow pace and the motor temp dropped right down, but the buzzer still was sounding. Get up to crusing speed for a few minutes and it will go off after a few minutes. I couldn't find the sensor on the right side of the motor, tan wire I think. Is it behind a cover on that side??

Help please.. :%

Re: 1992 75HP Warning Buzzer

Sticky thermostat or weak water pump.

Re: 1992 75HP Warning Buzzer

Silvertip said:

Sticky thermostat or weak water pump.

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Someone also suggested it could be a blown head gasket creating a pocket in the head.. Sound possible? Where is the thermostat located on this motor