[Fot] Faulty Water Temp Gauge?

[Glenn Franco]

Gary
If you don't want to spend the $ on an infrared temp device, Lisle (and 
many others) makes a drop in thermometer that goes in the radiator neck.
I have been using these for years without incident. At least you will be 
able to measure the true coolant temp and see when the thermostat opens.
Of course start with a cold engine. You can't measure on the run but you 
can't with the infrared either.The infrared will only provide surface temps.

If you have a fluke with or similar VOM with a receptacle for a 
thermocouple, you can insert the thermocouple under the upper radiator 
hose (or any other place you desire) into the coolant. Run the 
thermocouple wire into the passenger compartment and you can monitor 
your coolant temp at any speed or condition. We use to run hundred of 
these during vehicle development tests.

I agree with the other posts that it's likely a voltage stabilizer or 
bad sending unit, but you never know definitively until you test.
Good Luck
Glenn Franco

vintage.racer at comcast.net wrote:
> Hello All: 
>
>
> Need some opinions on what I think might be a problem with my 1969 TR6 water temp gauge is an electrical unit. Scenario: recently, I've noticed the car running a bit hot, ie, the needle within an 1/8" of the red zone on the gauge. I recall at normal operating temp, the needle should be closer to half way (ambient daytime temps in the 80 - 90 degree range). Once the needle reaches this "hot" location, it never seems to come back down at all, regardless of whether I'm at speed or stopped. To me, this is not normal. 
>
>
> What I've done so far: flushed the cooling system, filled with about 35% anit-freeze, remainder with distilled water; added a few ounces of Water Wetter; new temp sensor, new thermostat (180 degree), timing checked and spot on. So far no difference in the way the gauge reacts, indicates the engine is still running hot so I'm wondering if I might have a gauge going bad. Anyone have an experience with a faulty water temp gauge? Does it gradually go bad and give false readings? Thanks. 
>
>
> Gary 
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