Gauge reading hot

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mean58fury

mean58fury

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Hello everyone. I get the temperature gauge reading hot on my 1963 Valiant slant six, but when I pull over there is no boil over from the radiator. Is the car really hot or is the gauge malfunctioning? I replaced the temp sender. The gauge goes to hot after 15 to 20 minutes of driving. Does anyone have any idea why this would happen?
 
If it pegged to H , things to check for would be a short in the wire causing it to ground, possibly the wrong sender for that year, or you have an actual cooling system issue.
You have no boiling over or overflow hose puking?
 
Here is the first thing I'd do. Get yourself an IR thermometer. They sell them at Harbor Freight for about $25 all the time on sale. Then check the actual temp on the radiator and at the thermostat housing. You can also read the temp at the thermostat housing and see when the thermostat is opening. You will wonder how you ever got along without it.
 
We even stock the little IR thermometers at O'Reilly now. They are pretty nice.
 
If you look at the "H" on the gauge as a goalpost and the needle stays between the uprights you are okay. The radiator pressure cap raises the boiling point to about 240 degrees.
 
Thank you everyone. I happen to have an IR thermometer and will do as you said. The car also clearly needs a tune up as it appears to be misfiring somewhere. I just purchased it so I'll have to go through it.
 
mean58fury said:
Thank you everyone. I happen to have an IR thermometer and will do as you said. The car also clearly needs a tune up as it appears to be misfiring somewhere. I just purchased it so I'll have to go through it.
Click to expand...
I bit my lip to withhold mention of head gasket failure. Then you went and mentioned a skip.
Fill the radiator , leave the cap off and let it idle. Watch for a continuously repeating air bubble. Good luck
 
The gauge starts off as cold then goes to the middle in a few minutes and then very close to the H within 15 to 20 minutes of driving. The head gasket is a possibility and I will check it out. Thanks for the responses.
 
I checked the radiator cold and the coolant level was normal. I didn't start the car as I don't like running it in the garage and I was too lazy to back it into the driveway. I will diagnose it next weekend. Thank you everyone for your help.
 
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