Thread: Cooling system strangeness

Originally Posted by PhilipA

Have you just pulled the plug off the sensor and cleaned it?
Nanocom takes the signal from the ECU ie the sensor. If the plug is dirty both will read low.

I have a separate dry sensor next to the wet ECU one so I have a good idea how they corelate.
Regards PhilipA

Yeah, I’ve cleaned it to within an inch of its life…. As fuel temp is also low that exercise was more in hope than conviction.

Originally Posted by Markf

Well being a D2 there is no end to “stuff”. Today between Kiata and Belair the temp gauge dropped. No red light all seemed ok. Plenty of coolant in the tank, coolant circulating ok, hoses not pressurised, no visible leaks, oil ok, etc. Hooked up nanacom and it said 66.5 deg C. Hmmmm. Car ran like a charm up Mt Barker towing our 750kg camper with temp topping out at 72.5. My guess is that the thermostat is stuck open. Oh well I suppose it’s an opportunity to flush the cooling system and fill it’s with brand new red leaky stuff.

Hi Mark
Reckon your self diagnosis is correct. If you don't want to replace with "the red leaky stuff", I find the Blue OAT from penrite isn't as leaky

I finally got enough time to get the thermostat out and what a production that was. While I was grovelling around under the car I caught a glimpse of the engine mounts and the look to be as kaput as the thermostat, dammit. As suspected the thermostat is as kaput as the engine mounts. It won't even close if I stick it in the freezer for 30 minutes. Tomorrow will be fun putting the new (genuine) thermostat in and filling it all up with plain demineralised water which I'll drain after a day or so and refill with some leaky red stuff - I have enough for a couple of Td5's on hand...

Originally Posted by Markf

I finally got enough time to get the thermostat out and what a production that was. While I was grovelling around under the car I caught a glimpse of the engine mounts and the look to be as kaput as the thermostat, dammit. As suspected the thermostat is as kaput as the engine mounts. It won't even close if I stick it in the freezer for 30 minutes. Tomorrow will be fun putting the new (genuine) thermostat in and filling it all up with plain demineralised water which I'll drain after a day or so and refill with some leaky red stuff - I have enough for a couple of Td5's on hand...

Glad you found the issue.

With the various leaks and top ups since my rebuild over the last six months it was suggested by a mechanic friend that I should change the fluid over as the concentration is probably bad one way or the other. The interesting thing he said was to blow the system dry, suggesting to put an air hose into the bleeder and pressurize the system then take off the drain plug. Hadn't heard of such a thing before but he assures me that it will get all the fluid out...

So I finally got around to flushing the whole cooling system.
When I dropped the coolant to change the thermostat it had green coolant so I decided to fill it with rain water and carry on until I had time.
It took a LOT of rainwater to get the last tinge of green out of the coolant. Just draining it via the drain plug I only got about 6 litres out and after a refill with rainwater and a drive to get the thermostat open it still ran green. I think I disconnected every hose and pumped it full of rainwater until it overflowed from the filler. A couple of hundred litres I reckon.
There is not the slightest tinge of green now...

Seeing as I had concentrate I drained as much as I could - 6.5 litres - and just refilled it with concentrate to make up what should be the 13 litres that it allegedly holds. Job done and the coolant test kit from Nulon says 50% concentration...