What overheating alarm to use

[arch007]

Want to install an overheating alarm on betamarine engine.

Panel already has an overheating buzzer but would like to catch engine overheating earlier than the buzzer.

So was thinking of heat alarm on exhaust outlet. There seems to be some that involves a clamp around the exhaust hose.

Install thermocouple on engine block. Maybe on thermostat.

Other types of alarms ?

What do people use ?

Do not want keep monitoring temperature gauge to see if it rises over normal operatinb temperature.

Thanks.

[Sailmonkey]

There are the exhaust temperature alarms. These are most useful to see if the seawater stream has been interrupted.

Then there are alarms mounted to the block.

I’d personally mount an exhaust temp alarm. It’ll react more quickly if you suck up a bag or some other blockage.

[bstreep]

Exhaust temp alarm. Don't be tempted by the cheap ones. We had our engine panel redone by AC/DC - https://acdcmarineinc.com They have a good pyrometer. The guy is a bit full of himself, but they do make decent products.

[Phyrcooler]

As noted, an exhaust overheat alarm is probably the best early warning. Look up the Aquaalarm https://aqualarm.net/exhaust-engine-...gine-p-11.html
Or
https://www.borelmfg.com/

[Bundyon]

Mate, after writing about how good "Engine Guard" is & trying to upload some pictures of them fitted to my boat, I gave up when the lot disappeared to cyber space. Damn hardest site to upload pic's I have ever come across. Mind you I am not a computer boffin.
Imho use these, they are bloody excellent & top quality at a good price.

https://engineguard.com.au/

[Ken Pole]

check out UK-based nasamarine.com. they have a nice unit.

[Simi 60]

This is what I used on main engine and Genset

Has saved us more than once
Cheap insurance
$100 for one, $25 for the other.

https://www.cruisersforum.com/forums...rm-202270.html

[bstreep]

I will caution folks: If the probe is not inside the exhaust (like through a hole), you may not get the overheat warning as soon as you would like. Some exhaust hose can take quite a while to get hot enough to trip those wrap-around sensors.

[jamhass]

I, too like the Aqualarm coolant water flow sensor. It signals low raw water flow, so can often alert faster than many exhaust temp probes.

[CarlF]

I've have the exhaust temp alarm from Borel on two boats and have been happy (although it's never needed to go off)

Realize they do somewhat different things. The engine mounted temp sensor may show an overheat without the raw exhaust water getting dangerously warm.

But a blockage of your raw water intake (by perhaps a plastic bag) will activate the exhaust alarm well before the engine mounted sensor notices. This can give you precious seconds to get the engine shut down.

https://www.borelmfg.com/

[skipperpete]

It’s hard to beat “ Murphy Swichgage” for reliable adjustable set point temp and pressure gauges... electrical or mechanical, US company originally supplying the oilfield engine protection but now marine industry as well.
The make just about every type of engine protection alarm or shutdown system.... even oil pan level. The gauges look a bit industrial but work flawlessly.

[Simi 60]

Originally Posted by bstreep

I will caution folks: If the probe is not inside the exhaust (like through a hole), you may not get the overheat warning as soon as you would like. Some exhaust hose can take quite a while to get hot enough to trip those wrap-around sensors.

So you set a lower temp.
My probes are on the exhaust elbow and set for 55c, they usually run at around 37c in sub tropical waters.

Alarms go off if there is a blockage or impeller fail before the engine temp reaches 85c

[Nani Kai]

Originally Posted by arch007

Do not want keep monitoring temperature gauge to see if it rises over normal operatinb temperature.

My brother is a retired airline pilot. Early in his career he flew for a company that assigned each of their seven aircraft to specific pilots. On my brothers plane he rotated analog gauges in the instrument panel so that when they were at normal operating parameters all the needles pointed straight up. This allowed him to scan the panel and quickly pick out any aberration. That way he didn't have to monitor each gauge individually unless there was a problem.

If your temp gauge is analog this might be worthwhile to consider.

[Cheechako]

Clamp a "snap disc" thermo switch on the metal outlet elbow. Cooling water flow stops? > buzzer goes off pretty fast.
Use an electronic temp sensor to determine your maximum "normal" temp after a long motoring, then size your snap disc just a bit above that.

[Cheechako]

Originally Posted by bstreep

I will caution folks: If the probe is not inside the exhaust (like through a hole), you may not get the overheat warning as soon as you would like. Some exhaust hose can take quite a while to get hot enough to trip those wrap-around sensors.

Put it on something metal, I did the mixing elbow, worked fine.