Determining water temp w/an IR thermometer?

Like a lot of cars, my 57 has a temp gauge with no more than C at one end and H at another. The car spends a lot of time towards the H end of the gauge, but I don't know exactly how hot that actually is. So before I install a new temp gauge, I thought I'd just point an IR thermometer at the radiator and hoses.

So here's my question: assuming just for the sake of argument that the IR thermometer is accurate, if the reading on the return hose is 165, how much higher/lower might the actual water temp be? Is there a better place to measure? The radiator itself was ~145.

Am I making this too complicated? Is there an easier way?

Try the water neck on the radiator, not the rubber hose. The metal will track more closely with the water temperature. Then you could get the inlet and outlet hoses and see how much the rad is actually doing at that point in time...

IIRC, an infrared thermometer is going to display a rough average of teh temperatures in its field of view. I do not think it would be accurate at all in this application.

A gauge that bolts directly into the head of your 57 chevy is like 15$ at autovanceapazone. I would plug it in temporarily and drive the car around. Try to look at your existing guage and the new temp gauge to get a decent comparison.

Hope this helps.

Rob R.

In reply to wvumtnbkr:

Why do you assume it's a Chevy?

I know the better solution is to get a secondary gauge, I was just trying to (temporarily) make do with what I have in the garage.

Best I can remember my IR gun was within 10 degrees of my water temp gauge, point at the water neck.

Will wrote: Why do you assume it's a Chevy?

Fun game, I'll take another guess. Heinz 57?

2002maniac wrote:

Will wrote: Why do you assume it's a Chevy?

Fun game, I'll take another guess. Heinz 57?

Saucier.

In my profile garage.

With an IR you want to shoot the hose or metal that is flat black any other color or gloss black you will need to adjust the emissivity setting.

An IR thermometer will not give an accurate temperature of water unless the water is aggressively moving (as in a small whirlpool) . It's emissivity of water is different than solid materials. In the food industry we used IR thermometers to verify product temperatures. We had to check calibration of the IRs against a mercury thermometer in a container of water mixed violently while shooting the IR. Not that easy to do in a radiator.

Aim for the water neck on the intake. Is the stock setup electrical or mechanical?

In reply to Kenny_McCormic:

Well, the stock gauge that came with the car was mechanical. The stock sender that came with the engine is electrical. The gauge now operates as electric.

$5 meat thermometer stuck in the radiator fins as close to the upper rad hose as possible is going to give you a better reading. You'll just have to wait for the old girl to get fully hot, then pull over and look at the thermometer.

Pretty car. Sounds like a great build too!

Will wrote: In reply to wvumtnbkr: Why do you assume it's a Chevy? I know the better solution is to get a secondary gauge, I was just trying to (temporarily) make do with what I have in the garage.

No idea why I made that assumption. I think I actually read it like that. My brain equates 57 to Chevy. Weird.

And no, I am not a Chevy guy. Or a Ford guy. Or a Mopar guy.

Good luck with the diagnosis!

Rob R.

Does your car's "water temp" gauge measure water temp or the cylinder head temp?