Another mystery solved.

[oscarvan]

I've finally found a "Consulting mechanic" who will keep me out of trouble, for a fee of course, as I do my own work, and if necessary get his hands dirty if it gets tricky. We discussed my SB engine temperature indications which are suspect at best as they disagree with the IR point and shoot which is consistent across both engines.

We looked at the Instalarm panel and decided that after "BILGE" "OIL" and "FIRE", "HEAT" was engine overheat. He was, like me, unable to locate the sensors for same on the engines.

There was a cut off single white wire sticking out of each engine wiring loom when I got the boat. The surveyor didn't like them. He, nor I, had any idea what they were for.

Then the lightbulb went off and I connected the cutoff wires to ground..... Viola, the "HEAT" alarm went off. Apparently during the engine rebuild 10 years ago the system was disabled for unknown reason.

Morale of that story: Just because your alarm panel tests, doesn't mean it's actually monitoring the parameter !!!

So, I need to connect something to the wires and get overheat warning back. But, rather than a standard sensor in the cooling water I would like to put a sensor on the metal part of the exhaust right where the water gets mixed in. Thinking here is that if the water stops flowing the temperature there spikes instantly and warns me before the actual overheat occurs. Of course this does not protect against a loss of coolant or a thermostat failure which a sensor in the coolant would do.

Is there a common location where the coolant overheat sensor is located? DD 8V71-TI

Thoughts? And re. the sensor on the exhaust any recommendations for a clamp on sensor, normally open, to ground and what temperature value to use here?

Thanks.