Over-Temp alarm installation

[Dubed]

Good Morning.
I want to install an overtemp alarm (audible) on my MCM 3.7 190
Finall have the motor running great after a complete rebuild.
I monitor the temp and oil pressure constantly but it only takes a minute to overheat, and other than a failed elbow, this is the #1 cause of death to this motor.
Does anyone have a # for a kit that works well? I did see a Sierra kit, but want to make sure I get one that will work and be loud enough to hear.
I assume the new sensor can go right into the t-housing where the plug is, next to the temp sender.

 

[Alumarine]

I installed a Sierra MP41400 Oil/Temp kit a few years ago.
I mounted the buzzer under the dash. It is plenty loud enough.

 

[Dubed]

I installed a Sierra MP41400 Oil/Temp kit a few years ago.
I mounted the buzzer under the dash. It is plenty loud enough.

Thanks.
Thats the one I was looking at, but they arent alwasy the best quality. I was hoping someone else was using it.

 

[Bondo]

Thanks.
Thats the one I was looking at, but they arent alwasy the best quality. I was hoping someone else was using it.

Ayuh,..... If you don't like the buzzer, replace it with a horn off a car,....

 

[Scott06]

Thanks.
Thats the one I was looking at, but they arent alwasy the best quality. I was hoping someone else was using it.

you dont need to buy a kit . You can make your own just take power off the ignition on circuit the two switches can be OEM merc ones to make the ground connection to the block as in attached diagram. Would just make sure the temp switch is correct for the 3.7 that is overly sensitive to over heats vs other engines.

 

[Dubed]

you dont need to buy a kit . You can make your own just take power off the ignition on circuit the two switches can be OEM merc ones to make the ground connection to the block as in attached diagram. Would just make sure the temp switch is correct for the 3.7 that is overly sensitive to over heats vs other engines.

Interesting, easy enough. Thank you.
I especially like the "Disco Ball" option. I haven't seen it offered in any kit.

 

[Dubed]

you dont need to buy a kit . You can make your own just take power off the ignition on circuit the two switches can be OEM merc ones to make the ground connection to the block as in attached diagram. Would just make sure the temp switch is correct for the 3.7 that is overly sensitive to over heats vs other engines.

So, the kit is $40 for the 2 sensors and buzzer. Cant really go wrong with that u guess. Then just wire according to your diagram. Sounds like a plan

 

[flashback]

You probably will need to add a relay if using a disco ball..

 

[Dubed]

You probably will need to add a relay if using a disco ball..

Yeah but I'll finally get a bunch of hot chicks on the boat!

 

[flashback]

I'll be the relay!

 

[Dubed]

I'll be the relay!

At my age, hot chicks means Cornish hens fresh out of the oven!

 

[flashback]

At my age, hot chicks means Cornish hens fresh out of the oven!

Yeah I can relate.. but we still can dream...!

 

[Scott06]

Yeah but I'll finally get a bunch of hot chicks on the boat!

All chicks and disco balls aside looking at the specs for that kit the temp switch trips at 200 F. Not sure if that is too high for a 3.7? I was under the understanding that the 3.7 was very intolerant to even minor overheats before it spits a head gasket.

Not sure if others here can confirm if that temp is low enough to do anything for you on a 3.7

 

[Dubed]

All chicks and disco balls aside looking at the specs for that kit the temp switch trips at 200 F. Not sure if that is too high for a 3.7? I was under the understanding that the 3.7 was very intolerant to even minor overheats before it spits a head gasket.

Not sure if others here can confirm if that temp is low enough to do anything for you on a 3.7

Yes I saw that spec. Been searching but not seeing much else out there. 175-180 would be nice. Would also be nice to find a kit where you can set what temp kicks off the alarm. I suppose 200° would be better than letting it climb even higher, may save the day

 

[flashback]

You might be able to add or subtract resistance on the sensor by adding a simple resistor somewhere in the circuit. The electronic wizards around here could verify...

 

[Scott06]

You might be able to add or subtract resistance on the sensor by adding a simple resistor somewhere in the circuit. The electronic wizards around here could verify...

Its not a sensor it is a switch. It is open or closed electrically speaking

 

[Dubed]

Its not a sensor it is a switch. It is open or closed electrically speaking

You are correct

 

[Dubed]

All chicks and disco balls aside looking at the specs for that kit the temp switch trips at 200 F. Not sure if that is too high for a 3.7? I was under the understanding that the 3.7 was very intolerant to even minor overheats before it spits a head gasket.

Not sure if others here can confirm if that temp is low enough to do anything for you on a 3.7

I found a 190° switch at Seaboard. I would love to have it at go off @175 - 180°, but cant seem to find one

 

[Dubed]

I dont mean to "over-post on this subject, but is there any reason this wouldn't work? On at 185, off at 175°. It controlls an electric fan. I can't see any reason it needs a "marine" rating as long as its wired correctly.

 

[Bondo]

I dont mean to "over-post on this subject, but is there any reason this wouldn't work? On at 185, off at 175°. It controlls an electric fan. I can't see any reason it needs a "marine" rating as long as its wired correctly.

Ayuh,..... I think the 200* would be best, the 190* is pushing it,.....
At 175*, the alarm will probably be going off when ever you run it very hard,....