As this is a question that comes up a lot on this forum, I thought I would do a write up on temperature testing using both an infra red thermometer and a K type thermocouple.

I did this testing a while ago when I was working in a military calibration laboratory.

The write up in PDF so it can be downloaded. Please feel free to as questions.

 

From what I've read, which isn't much, IRs with an emissivity of 0.95 are mainly aimed at organic surface readings - for cooking and food, in other words. So I suspect any IR with a fixed emissivity won't be as good when reading rubber and metal in an engine, right?

 

It will be good for rubber, like a hose; but shiny metal will give false readings.

 

Thanks. Rubber's the main thing I'd want to measure, as as far as I can tell, the hottest part of my engine after a run is the coolant rubber pipes running to the top of the rad.

 

Most IR pyrometers are set at 0.95 emissivity from the factory, even the Fluke, although these expensive IR's have user setting to adjust emissivity.

0.95 is fine and on the Fluke 572 changing to 1.0 only makes a few deg difference.

Most important thing to be aware of is DTS (distance to spot ratio) if you hold the IR too far away it will measure everything in its spot. As was mentioned try to avoid shiny surfaces, black is best.

 

Cool. Or, rather, hot....
So the rubber hoses would be ideal targets then, from a suitably close distance.

 

If you've seen Star Wars you already knew lasers look cool but are inaccurate.

Thermocouples are the tool of a Jaguar mechanic. Not as clumsy or random as a laser. An elegant tool from a more civilized age.

 

I dunno kid. Hokey gizmos and ancient electronics are no match for a good temp-label on your hose.*
Perhaps something like this....
Temperature Labels

*Disclaimer: I have no idea if this is actually true of course. But they seem like an interesting idea...

"Handyman Solo. I'm mechanic of the Jaguar XJS. Louie here tells me you're lookin' for passage on the Interstate system?"
"Yes indeed, if it's a fast car."
"Fast car? You've never heard of the Jaguar XJS?"
"Should I have?"
"It's the car that made the Kegger Run in less than twelve breakdowns. I've outrun State troopers. Not the local bike cruisers mind you, I'm talking about the big Crown Vics now. She's fast enough for you, old man."

 

things sure have changed, we used to just reach down and grab the part to see how hot it was , and run hand along for flow check!

its quick and simple, by the time you get the gages and tools out ,temps have changed anyway! LOL.

Egads, i'm showin my age!

 

Actually I do do that. Or more like a gentle touch when it comes to the hotter parts....
The problem is, I don't know the difference between really hot and far too hot....

Mind you, when I first drove my car, and was having problems with it getting too hot, I needed an old towel around my hand to release the bonnet catch as the heat was searing. After the new rad and hoses and thermometers, which were done basically as soon as I got her, I can reach in bare-handed, though there's a definite different between a run where she doesn't reach full operating temperature (usually due to not being too long and having good flow through due to speed, not due to just driving for five minutes and stopping) and a run where the thermostats kick in (I assume) like in heavy traffic or hotter days or faster driving.