Variable temp guage after overheating advice please !

[bigdods]

A week or so back the chim overheated due to a failed otter - it was only for a minute or so as I pulled over and stopped. Lost about a litre or so of coolant, but once she had cooled down I checked the header which still had a little water in and swirl pot was still full. Replaced otter, fans cut in and out everything fine.

But today went for a spin and noticed the temp guage swinging from 50 to 70 then back to 60 up to 70 down to 50 ... etc... Got home cool down check swirl pot and expansion tank - still full. Heater working ok so water is circulating. Seems to be rev related, ticking over guage reads ok but rev it up (sat on the drive) and it starts swinging about. Until the fans cut in at about 80, then it sits at 80 no amount of revving makes it budge as long as the fans are running.

Im thinking the when she overheated its cooked the sender ? All advice gratefully received !

Cheers

Dodsy

[Cider Andy]

If you suspect the temperature sender, you could always try the Land Rover one (up on top behind the distributor, next to the injection system coolant temperature sensor).

Wire in a 120 Ohm resistor in series - posts on here suggest it's a more accurate reading than the original.

[that daddy]

Yes much more do it,no regrets.

[IPAddis]

Cider Andy said:

If you suspect the temperature sender, you could always try the Land Rover one (up on top behind the distributor, next to the injection system coolant temperature sensor).

Wire in a 120 Ohm resistor in series - posts on here suggest it's a more accurate reading than the original.

I'd happily do this if someone could explain why my concerns about a single point of calibration are unfounded.

Basically, a 120 ohm resistor might give a perfect reading at 80 degrees. However at 50 degrees it could be miles out.

Anyone tested it with an IR gun?

Ian A.

[that daddy]

just done this to my brothers chim,works spot on runs aroun 80 fans cut about 90ish,what more do you want

[bigdods]

Fans are supposed to cut in at 82 arent they ? With my new otter fitted last week they cut in at around 82 and back out just below 80.....IIRC 90 is the land rover otter which TVR replaced with a lower temp version.

Havent got the bible to hand to check all this out but thats what I recall.

[That Daddy]

Thermostat opens at 82 so doubt your fans should be cutting then(unless your gauge is off)my fans cut in around 90ish,usual cruising temp 80ish.