IR measurement for engine temps

[51_Meadowbrook]

I have read so many different answers to this that I decided to ask the wise folks here. I am trying to see where my gauge is reading in relation to the engine temperature but I’m not sure where exactly where I should be pointing the gun. Some say to point it to the upper radiator hose. Some say to point it on the metal of the water pump. Some say point it on the head. Each one of those spots produced a different temperature, especially the spot on the head near the exhaust port. Is the coolant temp going to be the same temperature as the metal engine? Where is the best spot to check the engine temp?

[Merle Coggins]

The thermostat housing would probably give you the best representation of the coolant temp returning to the radiator. You could also check the temp at various spots along the head to be sure there aren't any hot spots. And if you check the head  temp just above the temp gauge bulb that would give the best comparison to what your gauge is reading. Keep in mind that coolant temps can change quicker than the cast iron of the head, so your IR gun will only show you an average temp of what the coolant is doing. If you check at a core plug it could be more accurate, assuming there isn't a bunch of crud packed up behind the plug.

[51_Meadowbrook]

Essentially I’m trying to figure out why my Cadillac is vapor locking. I know this isn’t the site for that but it is a standard car issue and I have a ‘51 Dodge so I’m in the club but that thing doesn’t overheat anymore. I was reading the temperatures of the inner and outer radiator tubes and they are 209 and 185. To me that indicates that the radiator is cooling like it should. The water pump only has a couple hundred miles on it. The engine block was flushed. I’m not sure what would cause the heat in the engine like that. 

[zHxIxPxPxIxEz]

On 7/16/2019 at 11:39 PM, 51_Meadowbrook said:

Essentially I’m trying to figure out why my Cadillac is vapor locking. I know this isn’t the site for that but it is a standard car issue and I have a ‘51 Dodge so I’m in the club but that thing doesn’t overheat anymore. I was reading the temperatures of the inner and outer radiator tubes and they are 209 and 185. To me that indicates that the radiator is cooling like it should. The water pump only has a couple hundred miles on it. The engine block was flushed. I’m not sure what would cause the heat in the engine like that. 

My engine was hot tanked on rebuild. I had some plumbing issues to sort out, and asked the guys here why i wasnt getting coolant out of the engine drain plug. Low n behold, She was still dirty! Just like the guys said. 

To clean it out i went to highest watter jacket opening, and fit a conector for an air line (a shop rag) . with it open, hot, and outside i smacked it with the air gun. Allot of nasty gunk came out, and fixed some localized issues i had. 

mabey try blowing the block out