Last summer the water temp was showing 200-205 frequently, which I thought was a bit too hot. Didnt know why, since the elect fan puts out a tremendous amount of air, and the radiator has a new 4 row core. Thermostat is new 185 degree unit, and water pump new also.

So a couple days ago I decided to test the gauge by bringing water temperature to operating levels, and check the radiator with a thermometer, comparing it to the gauge. Since my wife is out of town I had easy access to her bi-metal meat thermometer. We also happen to have a Certified thermometer that goes up to 110 degrees. Brought a glass of water to 105, and put both thermometers in. The meat thermometer was cool by about 15 degrees, so it was adjusted.

Next stop was the barn. Got the water temp to 190 according to the gauge and then went and looked at the thermometer in the radiator. It showed 175.
Ah ha!

A trip to Autozone brought me in front of a Sunpro water temp gauge. I was a little leery of it, but it was $14 less than the Autometer (which would have to be ordered). Asked the salesman about Sunpro's accuracy (like they would know), and they said there hadnt been one returned to their knowlege.
Bought it and tested it in a glass of water heated to 170, using the meat thermometer. The gauge measured 150.

Returned it and ordered an Autometer. They kind of gave me an attitude on the return, too.

Today I installed it, and started the motor, bringing temp to 190 per gauge. Went front, and the thermometer said 190.

Success!!!

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46 1/2 ton with 56 292:thumbsup:

That is cool. It is not to often that you get a faulty gauge, definatly a bonus for you though.

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gotta love a pro street

Um. I have a Sunpro in Ol'Blue and it gets to 180, satys there for the most parrt. Unless I'm in stop and go in D, then it goes for 210. Maybe I should try your technic.....

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Down the two lane blacktop.
Oldskool Is Kool :thumbsup:
Ford Man From Way Back



Check out: hotrodhotline.com for my pictures.

Hey colorado if I was to guess I would have to say your gauge is most likely reading correctly. I assume you have a belt driven fan in Ol'Blue. This is quite normal for the temp to rise when you come to a stop as the rpm goes down the fan is pulling less air through the rad and the pump has slowed down the flow of coolant through the system as well as less fresh air being pushed through the rad just from driving.
Then again I would of recommended 46yblock to flush the block and never would of thought of something as simple as a gauge.

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gotta love a pro street

In my situation everything was new, or new rebuild, including the block. That was why the higher summer temps had me a bit puzzled.
Some of the auto parts houses reportedly have infrared Pyrometers, that can just be pointed at any part, motor, body, radiator, and read out temperature. When I asked about a pyrometer at the local Autozone, they gave me their patented blank look, and then went and got a 4 ball gauge for measuring antifreeze level and freezing point.
The thermometer is a great test if you dont have a pyro. However make sure you calibrate it. Since you wouldnt want to spend 30 plus dollars on a certified calibrating thermometer, just find out the boiling temp of water at your altitude, boil water, put the meat thermometer in, and adjust (the metal ones are adjustable).
After I had gone through this little exercise, I stopped by my retired mechanic friend's house with the truck to say Hi. Kind of proud of my accomplishment started telling him. In mid story he walked into his shop, came out with a pyrometer, and had the temp of the thermostat housing in 10 seconds. Good thing was it was within 2 degrees of the gauge.

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46 1/2 ton with 56 292:thumbsup:

Ya new WP, Thermastate, hose's, and heater core. Need to pull the radiator and clean it. Then go for an Elec.Fan. That should help. But the weather has got to get back to garage temp b4 I venture out to work.

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Down the two lane blacktop.
Oldskool Is Kool :thumbsup:
Ford Man From Way Back



Check out: hotrodhotline.com for my pictures.

Last week I did some driving with the truck. Outside temp was approx. 55. Truck was very slow to warm up. When on the road, with fan turned off, temperature would not go above 150. When standing still it would rise to 190 and require a burst from the fan.
First thought was that the thermostat was stuck open. Then started thinking about other more exotic, less probable causes. Found out that I did not understand the water flow correctly from radiator, to pump and engine, and was given a lesson there from another poster.
Bought a new cheapo steel bodied 195 stat to replace the steel bodied 180. When cleaning the mounting surface of the stat housing on the alum intake, noticed early galvanic corrosion at point of contact between stat and intake. Have been looking high and low for a 292 brass bodied thermostat, since brass would result in less corrosion than the steel. No luck. Was told that tap water high in minerals could contribute to the corrosion, so use distilled. Also was told that the antifreeze type was important, and Zerex GL-5 was recommended by two people, although Ford does not recommend it for vehicles prior to 1999.
A man at Carquest recommended a coolant additive used in diesels, and another person said that it was contraindicated for brass/copper radiators.
Found that the maker of the aluminum water pump and timing cover recommends the use of an anode in the radiator, and the radiator to be grounded, and the use of distilled water.
Located an anode at JC Whitney for $13.
The wife looked over my shoulder today as I was seeking the brass stat on the www. After telling her what I was doing, she made a wisecrack that isnt worth repeating.
The reward is in the journey?

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46 1/2 ton with 56 292:thumbsup: