Checking Temperatures With An Infrared Tester

Shadetree

Shadetree

Well-known member
A few weeks ago I checked the temperature of my heads and radiator on my 21 stud V-8 with an infrared temperature gun while the engine ran at a fast idle. I also ran the electric fan I had previously installed during the testing. It was evident that the #4 and #8 cylinders run hotter than #1 and #5. I would guess this is normal as they are the farthest away from the cool water source.


I started the test with a cold engine at 9:45 AM and stopped at 10:25 AM. I wasn’t smart enough to get the ambient temperature but it was probably in the mid to high 70’s.

These temperatures were taken just before shut down at 10:25 AM: The temperature gauge in the car showed at the top of the normal range.

Radiator:
Top- 183°
Bottom- 156°

Engine:
#1 Cylinder-182°
#5 Cylinder-180°

#4 Cylinder-203°
#8 Cylinder-194°


Five minutes after shut down with the electric fan running I checked the radiator:

Top-183°
Bottom-140°

The only conclusion I gather is the rear cylinders run hotter and the electric fan is effective. I had done a compression leak test earlier on with negative results.

Yesterday morning my wife and I took the car on a 70-80 mile trip and the temperature was in the high 70’s to low 80’s. It ran super with the temperature gauge indicating about 160°. The only time I used the electric fan was in town.

Shadetree
 
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I use my infrared thermometer all the time. It's a great way to find out exact temps throughout the system, radiator, t-stats, heads, etc.
Matt
 
It is a good tool and very reasonably priced. As far as accuracy I don't know how good it is, but when comparing from one location to another it shouldn't matter that much.

Shadetree
 
The laser thermometer shoots a cone which widens the further your away from the object. So the closer your are the more your able to pin point the temp. Dark dull objects respond the best. Wrapping electrical acts as a insultor. Black or dark green works the best. my 2 cents..... Gordon
 
I've noticed that gmc. When I'm 2-3ft away from the engine and check the lower part of the heads it seems to pickup the exhaust as well. It'll shoot up to 230.
 
Harbor freight has them, also at the tool vendors in the flea markets. We did a roast on the gas grill and I used one to set the temp inside the cover. Nice to have to check if you have a cylinder miss firing, great tool. Mine has a common 9 volt battery so replacement is not a big deal.
 
I think Harbor Freight has them for $27.95 minus 20% off plus a free gift. I have one and it works fine and is very accurate. I would be very careful not to get the light to close to the plug wires, it will fry it. I am speaking from experience. I remember someone saying to wrap the gun in aluminum foil.The only difference I see between the inexpensive one and the expensive one is the range, some will read over 1000 deg. and harbor freight reads around 500 deg.
Don
 
[QUOTEThe only difference I see between the inexpensive one and the expensive one is the range, some will read over 1000 deg. and harbor freight reads around 500 deg.
Don[/QUOTE]

I use a 500 degree rated one from HF to gauge my wood stove.
I've had it up to over 700 degrees. It reads progressively and I have no reason to doubt it is reasonably accurate.
 
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