"Home Made" Temp Alarm

[Brentathon]

Not sure if anyone has an issue with the way I did this, but since my 1991 boat didn't come with the Temp & Oil alarm system, I bought the Merc temp switch (p/n 48952), and simply wired-up a 12 Volt source from my ignition switch.
I would have to jump the wire to ground to test the alarm, and if the temp switch closes (from overheat), I can shut the alarm off with a on/off switch.
I'll still probably glance at the temp gauge quite often....it's become a paranoid habbit through the years.....

 

[Pete104]

Re: "Home Made" Temp Alarm

Why do you want to turn it off?

 

[Johnson110]

Re: "Home Made" Temp Alarm

Where and how much did you pay for that alarm 48952 ? I need one for my thermostat, They go for about 70 bucks looking for one!

 

[Bondo]

Re: "Home Made" Temp Alarm

Ayuh,... I made 1 years ago with an ole seatbelt buzzer,...
Just ground it through a sender/ switch...
Toggle or not is yer choice...

 

[Don S]

Re: "Home Made" Temp Alarm

Why do you want to turn it off?

When the alarm does go off, and you have to keep going no matter what, it's nice to be able to shut the noisy thing off. You know at that point it's overheating, you don't need the buzzer to keep reminding you.
On the oil pressure alarms that come on when you are starting the engine, I have installed momentary push buttons for people that don't want to hear the alarm screaming first thing in the morning in a quiet anchorage when starting the engine.

 

[Pete104]

Re: "Home Made" Temp Alarm

My point was, it's telling you that something is "wrong"! My thinking was to ignore the [alarm]. But if he wants that, more power to him!

I wonder if he will ever keep us informed?!

 

[Brentathon]

Re: "Home Made" Temp Alarm

I got the temp switch from boatfix.com.

I added an on/off switch mainly so if/when I overheat (hopefully never), I don't have a continuous annoying beep going on; I could reach under the dash and shut it. And the second reason would be in case the switch fails in a closed position.....although, that may be quite unlikely.
I would never simply ignore it.....overheating is perhaps the most scary condition....and perhaps the most common killer of marine engines.

 

[ENSIGN]

Re: "Home Made" Temp Alarm

The switch makes it to easy to ignore the problem.Most people don't have the common sense to turn the ignition switch OFF,you don't have to keep going

 

[Dshow]

Re: "Home Made" Temp Alarm

Given the OP design, how would one know when the fuse blows or corrosion makes a bad contact unless you test frequently? I would not want to kill the engine on an overheat or you would loose any cooling flow. I would put it in neutral and increase the idle speed.

Edit: If you believe a restricted cooling input or bad impeller is the root cause, It may not make sense to idle the engine more... Bottom line, you need to have an idea of root cause and then decide course of action.

 

[Brentathon]

Re: "Home Made" Temp Alarm

Given the OP design, how would one know when the fuse blows or corrosion makes a bad contact unless you test frequently?QUOTE]

Yes, I made a simple jumper wire, that I can touch one end to the positive terminal of the Temp switch, and the other end touch any clean spot on the engine (i.e. ground) to hear the buzzer. I plan to do that whenever I lift the hatch and inspect the engine/bilge/oil, etc., which is quite often.

My main idea from all this is: This switch is better than NO switch. In an overheating condition, every second counts....especially at cruising speeds. I KILLED and outdrive AND an engine from an overheat condition.....it happens real fast.
A flow switch on the incoming water from the drive would be another good alarm....but, I don't think I have the energy to mess with that.

 

[Howard Sterndrive]

Re: "Home Made" Temp Alarm

thanks for posting this Brent... looks good!