My IR thermometer measures about 165F to 180F on the radiator near the otter switch and on a black dot painted near the temp sender. the fans come on at about 175 and off at about 165. However the temp gauge is in the red at 165F.
The sender measures between 950 ohms and 600 ohms at 60F on several different tries. At 175F it is 31 ohms. What should the numbers be? I have one reply that it should be:
30C-330ohms
70C-70ohms
110C-11 ohms
I can’t find any tests in the factory manual but have read there is a voltage regulator that could be the problem, How is this best tested?
It appears the PO replaced all the smith gauges with new or at least rebuilt Smith gauges and the sender is new.
The instrument voltage regulator is attached to the back of the fold down instrument panel. It supplies 10V to the fuel and temp gauges. If it wasn’t behaving, the fuel gauge would also be reading high. But you can test directly by measuring the voltage supply at the gauge. Some electronic meters have a problem reading the IVR’s output, though.
Rather than second guess my water guage, and nervously firing my IR reader all over I’d like to be the persnickety type that gets an absolute reading from the sender, straight from the source.
I had a similar issue in my 69 FHC. I started with the temp sender… inexpensive and fairly easy to replace. Make sure you get the crush washer with the new one. When that didn’t make the temp needle go back to where it had registered (for years!) O-R, I bit the bullet and put in a new CoolCat radiator and fans. All good now. I then put in CC’s electronic voltage regulator as well, because that was just more old stuff in that car that could go at any tiime. Didn’t that that complication for fuel and temperature.
