Engine temperature scan

Where is the most accurate place to scan the engine area with a thermal temperature gun to compare to the temperature gauge? Thermostat housing? Radiator hose?

Andyrv6av8r said:

Where is the most accurate place to scan the engine area with a thermal temperature gun to compare to the temperature gauge? Thermostat housing? Radiator hose?

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The back of the thermostat (Aluminum Crossover pipe), will give you the most realistic indication of engine temperature.
The dash gauge sender is in the front of the head in about the hottest point on the engine.
The senders and gauges are notoriously inaccurate. Since the fan control switch is in the water crossover pipe
close to the thermostat, that is the best way to determine if the engine cooling system is working.
On any of the numerous vehicles I have owned, worked on and driven, if the fan system
cycles on and off when you are driving, I judge the system is working correctly.
If the fan comes on and does not cycle off.... Abort your mission.

Be careful with those IR temp guns. They are wildly inaccurate especially on reflective metal surfaces. Hoses read right but you are reading external temperature vs internal temperature.

Mine works as advertised with the fan cycling on and off. I replaced my electrical gauge with a mechanical one a while back. However that gauge stopped working and I replaced it again with the same unit. Those two gauges read within 5 degrees of each other so I guess I'm OK.

911joeblow said:

Be careful with those IR temp guns. They are wildly inaccurate especially on reflective metal surfaces. Hoses read right but you are reading external temperature vs internal temperature.

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Also, many people think that the temperature is measured exactly at the laser spot. In reality, those IR guns have a quite large spot in which they measure the average surface temperature. In cheap guns, the diameter of that spot can be 1:5 of the distance (say, you point the gun from 20 inches, then the spot has 4 inches diameter). Better ones have a 1:10 spot. Not really a problem if you know this, but I always laugh when people point a temp gun at some piping at the ceilling (so several feet away) and then declare the temperature to be 82.78 ° F.....

Would using a FLIR camera provide more accurate readings?

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ANY IR device would be more accurate then the factory gauge and sender if you ask me....

Taken with a flir one

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