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Old 06-01-2020, 03:09 AM   #1
Lt. JG
 
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Default Thermostat and alarm replacement

I have an intermittent alarm that has gotten steadily worse since last season. It only happens after engines are warmed up. Iím guessing itís temp alarm (drive reservoir full).

I finally diagnosed it to the starboard motor which runs about 176-177 on the gauge. Port is about 175.

Iím ready to throw some parts at it before paying the marina to troubleshoot as the parts are relatively cheap. My guess is faulty sensor since it sounds like Morse code. I may buy an IR gun just to confirm nothing else is going on. I have a few questions;

1) is that operating temp normal?
2) what areas should I hit with the gun and whatís normal vs cause for concern?
3) I canít get a clear explanation online which sender is the helm gauge vs alarm. Does anyone have the PN for the alarm or can confirm which side of the manifold itís on.
4) I plan to replace the thermostat as well. Is it an easy job to replace thermostat and sensor? Anything I should be aware of beforehand?

4.3 carb alpha 1, raw water cooled.

Thanks!

BTW - painters tape over the engine alarm speaker did the trick to diagnose which engine (both alarms sound identical). If you have another trick please share!


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Old 06-01-2020, 11:23 AM   #2
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The alarm sensor has the tan/blue wire while the helm gauge has a solid tan wire. I would first disconnect the tan/blue wire and operate the boat for some time to confirm the alarm doesnít sound. If it still sounds I would try disconnecting the oil pressure alarm sensor and finally gear lube until you isolate the issue.
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Old 06-03-2020, 02:40 PM   #3
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I don't think that small of a temperature difference would cause the alarm to come on, but not sure what temperature the alarm is set to.
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Old 06-03-2020, 03:26 PM   #4
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Quote:
Originally Posted by Trey5684 View Post
I don't think that small of a temperature difference would cause the alarm to come on, but not sure what temperature the alarm is set to.
The OP is suspecting a faulty sensor so the actual temperature really doesnít matter.
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Old 06-03-2020, 03:48 PM   #5
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Oops sorry mmwjr, I misread and thought op was suggesting reading was correct and wanting to know also if those were normal readings. My mistake.
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Old 06-03-2020, 05:48 PM   #6
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Quote:
Originally Posted by Trey5684 View Post
Oops sorry mmwjr, I misread and thought op was suggesting reading was correct and wanting to know also if those were normal readings. My mistake.
Call me Mike. Nothing to be sorry about.

Yes the OP said gauge is correct but the alarm which uses a different sensor is intermittently going off.
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