Have I got a Cooling Issue

[chris.t]

OK here’s the issue.

I have checked my records and the car had a coolant change May 2023. The car was off road from about October last year til now.

Took the car for a run to see if things were ok after the lay up and noticed that the temp gauge barely got off the zero cold) line. Last year the normal running condition was a ¾ from the cold position and the ¼ position on the gauge.

Ran the car until the fans came on which they did just a little over halfway between the ½ way mark and the ¾ mark on the gauge. When the car was new the fans came on at the 3/4 line. Concluded that the thermostat must be stuck open. Stupidly I didn’t check that coolant was going through the radiator at this stage, I sort of ASSumed that the gauge was telling me it was. I then drove the car and the temperature gauge soon dropped down to the near zero position again.

I’ve just taken the old thermostat out and it was closed. Dropped it into boiling water and it stayed closed. So the thermostat definitely is not right and has now been changed.

Just took the car out for another test. Gauge now reads what it did last year (still lower than when I bought the car in 1991!). Fans come on as described above. When I started the car there was, I think, more than usual condensation vapour in the exhaust gas which did clear when the car was warm.

So I think the gauge is out of calibration for starters but what concerns me is the old thermostat on inspection, stayed closed in boiling water and by running the car until the fans cut in would have damaged the engine. I’ve inspected the oil and there is no sign of coolant contamination.

Your thoughts would be much appreciated, it’s got me baffled!

[Simon_P]

The cooling circuit and the temperature gauge circuit are different.

Use elanscan to see what is actually happening as a startpoint.

[chris.t]

If I could find my blasted lead I would!

Is Geoff S still the purveyor of these?

[Tuga2112]

worth noting that air pockets can be rather tricky to resolve. and take a few miles to move about.

when i did the timing belt, i had one that would only shift when driving, and was soo big, that the whole reservoir went from full to empty when it filled.

[Simon_P]

If I could find my blasted lead I would!

Try the old school way then.
With a DVM measure the resistance on the CTS
Feel the top hose when it goes from cold through warm to too hot to hold read the resistance and compare to the values in the wiki.

[chris.t]

If I could find my blasted lead I would!

Try the old school way then.
With a DVM measure the resistance on the CTS
Feel the top hose when it goes from cold through warm to too hot to hold read the resistance and compare to the values in the wiki.

I really should find out what temp the fans kick in too, so ES is probably the best way to go.

[FunElan]

Ive found my gauge to be out of calibration when the car is dead cold. If I've been driving for a day, stop the car, have a coffee, then start it again 30 minutes later, the gauge responds much quicker. Perhaps our grounds are just a little loose with age?