Volvo MD 2020C - Overheating Alarm Activated

[rscary]

I would be very Interested to hear anyone's comments on this the problem of mine. Basically the over temp alarm went off recently when sailing my Moody S31. It was around 10 minutes after starting the engine. After some investigation and having changed the exhaust elbow, thermostat, cleaned the heat exchanger, checked fan belt tension all to no avail I began to think about the sensor itself. The problem was strange in that after every component changed and test the alarm would always go off around 10 minutes from starting the engine from cold. In the end I disconnected the sensor lead to the instrument panel and guess what? the alarm still went off!! I managed to obtain a DVM with a thermocouple and took readings around the engine and found an average temperature under load at 2000 rpm of around 70 degrees C.

This provided me confidence to continue running the engine but the problem still exits. I'm having to switch the alarm off at the instrument panel where it kills the sound but still continues to flash. This is okay in the short term but not something I want to put up with. Not only that I obviously need an alarm that provides me true overheating issues not false. I am now thinking about installing a temperature and alarm independent of the integrated system.

Thanks for you help

Regards

 

[VicS]

If the high temperature alarm sounds with the sensor disconnected it is very probably due to a fault in the panel or possibly a wiring fault. Confirm though that the wire you are disconnecting is a white/brown wire.

I note that you did not say anything about changing the raw water pump impeller. This would be near the top of most peoples lists of things to try but your temperature measurements do not indicate that it needs changing