'53 Temp gauge on 12 v.

[Dale Fairfax]

Just got my '53 F-100 (with 337 Lincoln Flathead) running. This was a body off resto-all new wiring on 12 volts but original gauges in dash. We used Runtz voltage reducers on the gauges. The gas gauge and the fuel gauge work fine. The temp gauge rests at max hot. Turn the key on and it moves to cold (but not all the way). Start the engine and within a very few minutes it maxes out on the hot side. The actual engine temp has been checked with a thermometer in the radiator and a heat gun on the heads and it's reading about 180 (and that's after running long enough to actually get to operating temp.) Any ideas? Thread sealant on senders?s

 

[41ford1]

I am not familiar with the sensor setup on the 337. If it's like the Ford there are two sensors. A two terminal post that is basically an over temp switch. It opens the circuit at about 212° The temp sensor is sensor the single terminal post unit. It sounds like the gauge is working. I suspect one of the sensors is bad.
Try:
1. Disconnect the wire from the gauge at the two post switch. Ground it to the block. Turn on the ignition. The gauge should go all the way to cold and maybe beyond. If it does the gauge is good and you have an issue with one of the engine units. Turn off the ignition. If the gauge doesn't go all the way to cold it needs to be adjusted or replaced.
2. Disconnect the other wire at the two post switch. Connect it to the wire from the gauge bypassing the switch. Turn on the ignition and see if the gauge goes to cold. If it does, start the engine and let it warm up. You should see the temp climb on the gauge without going to hot. If this reads good then the switch unit is bad. If it goes to hot and you are sure it at 180° then the single post unit is bad.

 

[53ash]

If your gonna drive alot, you might consider running two modern temp gauges on the motor. Sure don't want to cook a motor due to not knowing the temp.

 

[Merc Cruzer]

Dale:
I have a 53' Merc that had the same problem. I bought new sending units and replaced the gauge with the same results...I finally gave up and installed two manual gauges w/ sending units. This turns out to be a better set up since the original system was marginal at best. With the wire not grounded for the dash gauge, it reads to the top of hot, so I just grounded the wire so it shows cold all the time...mental thing.....anyway it is nice to see the "actual" temp of each head.