Temperature gauge accuracy

[Rex T.]

During the 14 months that I have owned my 67 w/ L79 engine, the temperature gauge has always registered no more than the first mark (unless I was in slow moving traffic on a hot day), which I think would be approx 140F??? Anyway, today I pulled the thermostat thinking I would find a 160F stat, but it was actually a 180F. Now, I wonder if the gauge is off or it is the temp sending unit. The car does retain its original Harrisson radiator and no leaks. Any suggestions?

Thanks,
Rex

[Duke W.]

Re: Temperature gauge accuracy

Consider yourself fortunate. Nine out of ten temperature anamoly complaints are overheating.

Put the themostat in a pan of cold water on the stove with a meat thermometer and slowly heat the water to a boil. The stat should begin to open at about 180 and be near full open (or at least over halfway)when the water boils. Thermostats can go out of calibration as they age.

The best check is an IR gun pointed at the radiator outlet hose. This should be done first to determine if the problem is in the sender/gage or thermostat. A lot of modern sending unit replacements are not properly calibrated for the gage. There are reports that the Wells TU-5 gives accurate readings.

Duke

[Rex T.]

Re: Temperature gauge accuracy

Thanks Duke. Is the Wells TU 5 that you refer to a temp sending unit or an IR gun?

Thanks,
Rex

[Jack H.]

Re: Temperature gauge accuracy

The Wells TU-5 is a temp sending unit manufactured and distributed by Wells...

On the accuracy of the temp reporting system, there are MANY posts in the archives. Remember it takes 'two to Tango'...

That means the gauge itself has to be in factory cal AND the temp sender has to conform to original specs. Either or both can be off the mark!