Low coolant alarm. Which one?

I've had the Engine Saver in mine for several years. Nice & simple & self tests each time ignition is turned on. Easy to fit to the TD42, just screws into the thermostat housing. Probably much as Turtle's diagram, but with a self test function & a buzzer (loud) as well as the LED. Expensive for what it is, but cheap for what it does.

Mine came on for the first time not long back, just after I changed coolant which needed topping up.

Harder to miss an audible alarm than just a light. The self test is essential imho, otherwise you have no idea if it is working.

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Originally Posted by mudski

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

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Wow, now I have to drag out my metalurgy books. Maybe by choosing the right probe material could make it actually reduce corrosion.

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On electrolysis & low coolant alarm http://www.enginesaver.com.au/Engine...C_DC_Page.html

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Originally Posted by mudski

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

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I wondered the same thing. Pretty sure the commercial units with a probe use an AC current on the sensor to get around the corrosion issues.

https://www.redarc.com.au/low-coolant-alarm

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Features

AC sensing to avoid corrosion
Suitable for 12 volt and 24 volt systems
The buzzer operates if the sense wire in the system is broken
Built-in anti-slosh delay
Output for external alarm and/or indicator

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At 14 volts with a 560 ohm resistor the max current would be 25 mA and only whilst the ignition is on. With positive voltage on the probe any electrolytic action would mean any corrosion would be on the probe.
The bigger problem in vehicles is the galvanic action between dissimilar metals. A mixture of aluminium and iron causes the aluminium to corrode, and this occurs 24/7. That is why coolants need to have corrosion inhabitants. If you used a zinc or zinc plated probe then it would act as a sacrificial anode to both iron and aluminium.

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We were talking about this yesterday, a workmate has the Redarc & has fitted the probe in the top hose using a Davis Craig adapter.
As I see it the top hose and the thermostat housing will have coolant in them right up to when the radiator is empty as the water pump will pick up coolant from the bottom of a half full radiator & pump it through the engine, thermostat & top hose.
My suggestion was to instal a probe in the ZD30's radiator cap which is just a blanking cap & has no pressure relief. It is at the very top of the radiator and would give earliest warning.
Graham

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Originally Posted by GeeYou8

We were talking about this yesterday, a workmate has the Redarc & has fitted the probe in the top hose using a Davis Craig adapter.
As I see it the top hose and the thermostat housing will have coolant in them right up to when the radiator is empty as the water pump will pick up coolant from the bottom of a half full radiator & pump it through the engine, thermostat & top hose.
My suggestion was to instal a probe in the ZD30's radiator cap which is just a blanking cap & has no pressure relief. It is at the very top of the radiator and would give earliest warning.
Graham

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I know with my Davies Craig one in the top hose of the Pajero, that it will set the alarm off with about 1/2 a litre missing. They are pretty sensitive to dropping levels.

I have 2 of the eg-01/02 with 2 sensors, so 4 total. 1 sensor hooked up to monitor water temps in and out of radiator, second monitor is being used on oil, working on hooking this up tomorrow on oil filter and oil cooler. They are simple, robust and aussie made in cairns QLD. The designer is readily avail and spare parts easy to get - have pinched a sensor wire twice - but my error in installation caused that. Happy with the gear and small to mount in the car.

I just spoke to a bloke who has the redarc unit. I asked him about it, since I remembered your thread.
He said the unit takes DC volts, from the car so 12VDC. But the sensor is fed AC volts from the unit..... Hope it helps .

So I looked up the PDF file for it.

http://www.nissanpatrol.com.au/forum...id=71223&stc=1

I ordered the Redarc low coolant unit today. I bought a Redarc brake controller last week and was impressed with the quality of the construction.