Do note that the commonly available, that is something other than what the U.S. Military or N.A.S.A. might have, "I.R. Temperature Guns" are often prone to interpreting the values being sought improperly; as this is a referred value that can be influenced by, among other things, the specific items' emissivity, surface material, including color & finish texture, and then there's also interference from the environmental factors.
Also realize, that even "if" accurate, this value is only as of the actual surface, aka not the "core temperature". So for example, if "shooting" the radiator core (tube & fins), that which is being presented is the "surface temperature", not the actual water temperature within; and as with something like this, the difference "should" be significant!
Scott.
Also realize, that even "if" accurate, this value is only as of the actual surface, aka not the "core temperature". So for example, if "shooting" the radiator core (tube & fins), that which is being presented is the "surface temperature", not the actual water temperature within; and as with something like this, the difference "should" be significant!

Scott.

