Universal M25: strange water temp alarm behavior

[sorcererdog]

Universal M25. On startup, water temp alarm goes off, beeping and flashing. Faster RPMs make beeping go faster. Coolant is full and flowing. Temp is cold (as I say this happens immediately on startup). Has just started doing this after five or six outings. Has anyone ever experienced this? Thanks, Roger

 

[Ralph Johnstone]

Firstly, welcome to the site.

This sounds like a partial short in your temperature switch (alarm) circuitry. The reason for the increase in the speed of the beeping is that your alternator is turning over faster and slightly increasing the voltage of your 12V supply i.e. your batteries.

Are you OK with hunting down an accidental ground ?

 

[sorcererdog]

Yes--will check this out. Thanks

 

[JoeWhite]

I am not new to this problem. In my case the alternator bracket was broken or cracked allowing the alternator to vibrate more and its upper bracket was causing the engine to vibrate more. This caused the high temperature by-metal strip to vibrate excessively and making contact internally to its case. You can test this by pushing hard on the alternator bracket while the engine runs and see if the alarm stops.
Let us know what you find.
Visit my website regarding this problem

Sail La Vie | 1999 Catalina 36 MK II

mei1970.org

 

[Ralph Johnstone]

This caused the high temperature by-metal strip to vibrate excessively and making contact internally to its case.

It sounds like you're referring to a high temperature alarm for an alternator while the OP is having a problem with his high temperature coolant alarm.

Close but no cigar .

.

 

[JoeWhite]

Ralf. I am refering to the coolant high temperature alarm sensor that is located at the top of the engine at the front.

 

[Ralph Johnstone]

This caused the high temperature by-metal strip to vibrate excessively and making contact internally to its case.

My apologies for my misread here.

With the reference to the high temperature by-metal strip , reading along quickly with all the details about the alternator, I mistook this temperature sensor as being associated with the alternator which was being discussed.

Mea culpa and I'll remember to read a little slower next time.

Close but no cigar .

PS. The cigar's in the mail.

 

[sorcererdog]

Thank you for your suggestions. Will check this out and let you know.

 

[JRT]

The coolant temp alarm is a sensor on the the lower port side of the engine. It is very well know that Catalina used a blade connector that will shake lose with engine vibration. You have to fold forward the engine hatch, lie flat with a flashlight, on the bottom side between the engine and head bulkhead to see it. It's a total pain to fix. I'm almost certain the increase noise is just because it is shaking around a lose connector. I've replaced mine with a marine grade connector and it helps, but still comes lose every now and then.

 

[sorcererdog]

Discovered short circuit at the panel (which was a total b*tch to open with the wheel/autopilot still in place). Screaming and flashing stopped. So far so good. Thanks for all the great suggestions. I really appreciate this group.

 

[Ralph Johnstone]

Discovered short circuit at the panel

Congratulations .

Can you now short out the temperature sensor at its terminals just to be sure all is in order with the high temperature coolant alarm circuit ?

 

[Tom J]

Discovered short circuit at the panel (which was a total b*tch to open with the wheel/autopilot still in place). Screaming and flashing stopped. So far so good. Thanks for all the great suggestions. I really appreciate this group.

Yeah, much easier to just pull the wheel off, and the autopilot is just a quick disconnect. This is a good time to grease the wheel hub, and make sure the wrench for the wheel is handy, since the wheel will have to come off in a hurry if you need the emergency tiller.