Checking temp

[jimjumper]

I imagine this has been asked multiple times before but I found it a little tough to phrase the question for the search. My Yanmar 240D doesn't have a temp gauge (although I am going to install one) so I purchased a laser temp gauge. Where on the engine does one check for the actual operating temp? I found quite a variety in temp in the upper and lower radiator hoses, upper and lower block, and the sending unit for the idiot light. I've never gotten a reading higher than 180F at any spot but would like to know when I'm using it what is safe.

 

[countrybumpkin]

Best place is at the thermostat housing , that's the water that is coming from the block and headed back to the radiator.

 

[dickfoster]

I imagine this has been asked multiple times before but I found it a little tough to phrase the question for the search. My Yanmar 240D doesn't have a temp gauge (although I am going to install one) so I purchased a laser temp gauge. Where on the engine does one check for the actual operating temp? I found quite a variety in temp in the upper and lower radiator hoses, upper and lower block, and the sending unit for the idiot light. I've never gotten a reading higher than 180F at any spot but would like to know when I'm using it what is safe.

You'd want to read at the temp sensor for the idiot light. If you have an ECU this is likely where the ECU gets its temperature data from too.
The temps had better be different for the upper and lower radiator hoses or something is for sure out of whack.
BTW those non contact thermometers aren't very accurate. Many DMMs today come with a contact thermocouple and a temp function on the meter that will give you a much better and more accurate reading.