Where Measure Engine Temp. with IR

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4 cyl. Ford Engine on Kohler Standby Generator. VERY stout radiator/cooling fan system. My service tech. shot a few IR readings around the thermostat and got 130F +/- and said the unit is running low and needs a hotter thermostat. I shot the oil filter at 175F and the oil pan at 185F.

Where is the best place to take IR readings on an engine to determine and/or interpret if it is operating at the correct temperature?

Thanks
 
Certainly the oil pan and oil filter will be hotter than the coolant. I believe the service tech took the readings at the correct spot, that is at the thermostat. I'm not sure what Kohler suggests but if this was a car engine 175-195 F would be more appropriate and if was a modern GM V8 it would be 210 F.
 
The oil filter will give you close to the oil temps in the oil filter. The oil pan will give you close to the oil temps in the oil pan. The radiator will give you close to the coolant temps in the radiator area where you shoot the temps and the T stat housing the temps of the coolant in that area. I would guess the t stat should be 160* f or higher. The tech is telling you the coolant temps are too low. Why measure the oil temps?
 
The thermostat housing sits on the engine front, perched up a bit, directly in front of the cooling fan. It gets bathed in cool air and I wonder how much effect that has on the IR reading. Ford VSG-413 engine:
805435_vsg411_product.png


Good pic here if my link doesn't work: https://www.manualslib.com/manual/805435/Ford-Vsg-411.html#product-VSG-413
 
From my use of an IR gun on super-heated steam boilers and combustion furnaces, the air temp has little to no bearing on metal surface temps. If I were doing it, I'd also want to know the highest temp on the engine block/heads.
 
I doubt that a temp is spec using an IR gun anywhere on that generator. So no real answer can be given.

I assume it was under load and fully warmed-up before IR temp reading? Is the mechanic trying to say it has a bad T-Stat, low on coolant (air pocket), bad water pump or bad design? If he's using and IR gun, he should be able to tell you why it's running cool since he "knows" it's running cool.

Seems a water cooled generator should have a temp gauge.
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Probably not an accurate way to measure internal coolant temps, since IR is measuring the radiated surface temperature.
 
A thermocouple taped onto the surface with aluminum tape will give a better temperature reading. IR gun will most likely be low because it assumes a black body radiating surface.
 
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