Low coolant alarm. Which one?

[mudski]

So I had the rear gasket on the lower part of the thermostat housing go on me last week. Coolant was absolutely gushing out. Lucky for me, I have a nose that requires me to use a yard glass to drink from, so I smelt it pretty quick. So thats all fixed, surprisingly easy job to do, and its got me a little concerned now. If I were to ever lose water again, and I have a cold and my schnozz is blocked, I may be up one of those creeks in a barbed wire canoe with no paddle. I really don't want to be cooking my engine....

I have looked at a few different alarm setups.

• Redarc https://www.redarc.com.au/low-coolant-alarm
• Davies Craig http://daviescraig.com.au/product/lo...it-12-24v-1035
• Engine saver http://www.enginesaver.com.au/Toyota_Nissan.htm
• Engine Guard http://www.ebay.com.au/itm/ENGINE-GUARD-EG01-1-New-Model-Temperature-Sensor-Gauge-low-coolant-alarm-/152447318916?hash=item237e917b84:g:PggAAOxyuR5TbBq Q
• EG2 http://www.ebay.com.au/itm/SIMPLE-WIRING-TEMPERATURE-GAUGE-ALARM-Detects-Low-Water-Coolant-EG2-/111976228387?hash=item1a124da623:g:H1YAAOSwstxVQgF K
• Engine Watch Dog http://www.ebay.com.au/itm/ENGINE-WATCHDOG-TM1-NEW-MODEL-TEMPERATURE-SENSOR-GAUGE-LOW-COOLANT-ALARM-/142263205052?hash=item211f8c3cbc:g:BrQAAOSwECZUrEF k
• eBay cheapie http://www.ebay.com.au/itm/Low-Coolant-Level-Alarm-12V-Buzzer-LED-/121532123147?hash=item1c4be1080b:g:89IAAOxyGxxSLdw A

What I don't really want is another display unit on the dash. Just a hidden unit that will scream its titties off when low coolant is detected.
So this knocks out Engine Guard, EG2 and Watchdog. Maybe the Davies Craig one too. Also with the Engine Guard, EG2 and Watchdog, I am not sure how the low coolant part of these kits work, I see no sensor in their kits.

This leaves the Redarc, Engine Saver and the Ebay Cheapie. One on my concerns is will the eBay cheapie and the Engine Saver produce any current through the coolant? Stray currents I really don't want. Then I look at the Redarc unit, Nice and compact, I can hide it away, I can put the sensor in at the bleed hole on top of the thermostat housing, which I don't use anyway, but. The unit self tests every time you turn on the car. I already have two Redarc gauges that do this and to have a third device do it, I reckon will do my head in.

So. Who's running what? What are your thoughts? Are there any other units I have missed?

Thanks in advance...

[threedogs]

What about a Murphy low coolant siren
you could hook up a sender to a reverse style horn
they are small and would tuck under the dash easily

[Turtle_au]

Random thought..... what about a flow switch/meter in upper radiator hose?

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[Coger]

I fitted a datatron, made by "flexible drive agencies". Sensor in top of radiator, module under dash, screams with anguish when activated. www.flexibledrive.com.au.

[stevemc181]

I have the Davies Craig one on my Pajero. I won't be using the same one on the Patrol. It has no self test mode so you never know if its working or not, and if I wash down the engine bay it seems to trigger the sensor, so I am guessing the connection isn't waterproof.

[mudski]

What about a Murphy low coolant siren
you could hook up a sender to a reverse style horn
they are small and would tuck under the dash easily

This also uses a gauge, something I dont want.

Random thought..... what about a flow switch/meter in upper radiator hose?

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Yeah I dont want to be adding adaptors into the hoses. Just means another place for a leak to happen.
I have a spot either in the top of the radiator and also in the top of the thermostat housing, both are there and ready for the job.

I'm leaning toward the engine Saver unit at this stage. I have emailed them and asked about current flow issues causing electolysis, if there is any, with there unit....

[Hodge]

Watchful eye on this.

[Turtle_au]

Random thought mk2....
Trying to remember correct terms, I think it is a voltage divider to drive a LED from 12volts. Basically a resistor one end connected to ignition circuit other to one side of LED. Other leg of LED to earth. Correct polarity of LED and correct resistor size and it will light up.
Now put an insulated probe into radiator and connect to middle of resistor/ LED circuit. When probe in contact with coolant it should hold middle of divider to earth, when coolant drops below probe no earth point and LED will light.

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[Turtle_au]

Got the brain lubed up and decided to draw the circuit up complete with sizing and Jaycar part numbers. LED should be bright enough
LED Circuit.jpg

[mudski]

Got the brain lubed up and decided to draw the circuit up complete with sizing and Jaycar part numbers. LED should be bright enough
LED Circuit.jpg

Yeah wow. Is there any current flow issues causing electrolysis with this setup?