Temperature alarm going off

[Andrew1]

I have had an ongoing problem with the temperature alarm that I need help with.
The boat is a 1998, Bayliner 2355 with a 5.0L Mercruiser with as closed cooling system.
The issue is that the temperature alarm is going off with the RPM over 3000 and the temp gauge indicating approx 180F. I confirmed the temperature in the sensor area, the engine block, and the manifolds with an infrared gun and it showed nothing over 175F. Despite these readings, the problem seems to be temperature rather than electrical related because it only starts when the gauge reaches 180F and stops when the gauge drops below 180F
I replaced the temp sensor and nothing changed. If I disconnect the sensor, the alarm stops. Except for this problem, the engine runs smooth and it seems to have enough power. Any thoughts anybody?
Thanks,
Andrew

 

[Haut Medoc]

Re: Temperature alarm going off

Have you pulled the end caps off of the heat exchanger to see if it is partially clogged with debris?.....
When was the last time the raw water impeller was changed?....
Sounds like the alarm is working as it should & your engine is starting to run warm......​

 

[Andrew1]

Re: Temperature alarm going off

I had the whole cooling system checked/replaced including the impeller, the water pump, the heat exchanger, and the thermostat. No problem was found and no change in the alarm condition. At what temperature should the alarm go off? I thought it was around 200F.
Thanks,
Andrew

 

[Haut Medoc]

Re: Temperature alarm going off

That I don't know.....
& you are probably right about the 200*.......:redface:
You were asking for thoughts.....
One other thought is that the alarm sensor itself is going bad.....
I would not know how to tell you to test it though......​

 

[hydrick]

Re: Temperature alarm going off

i had the same problem years ago and once i replaced the sensor it was solved.remember ther's two, mine was the one at the front manifold.
1993 4.3

 

[snosptz]

Re: Temperature alarm going off

I have the same problem. Where is the other sensor other than the one by the thermostat housing?? Did you solve your problem of the alarm going off? If so what was the answer??

 

[Don S]

Re: Temperature alarm going off

Start a new thread with your question. This thread is 2 years old and belongs to someone else.