I don't remember where I got this list, maybe TF:
IR CHECKLIST
Alternator: Wave the IR pyrometer around the alternator case while holding the trigger, use the highest reading.
Exhaust, dry and wet: No part of the exhaust system that can be touched should exceed 200°F. Ideally, the wet portion, the parts that rely on hose and fiberglass pipe, shouldn’t exceed 160°F. Use the same scanning technique as you would with the alternator, looking for the highest temperature.
Stuffing box: For both conventional and dripless, scan the stuffing box as well as the cutless bearing if one is installed in the shaft log just aft of the stuffing box. The temperature shouldn’t exceed 30°F above the temperature through which the vessel is moving.
Coolant expansion tank (where the pressure cap is located):
The temperature should be very close to that shown on your dashboard instrumentation, if it isn’t, there’s
a problem.
Oil pan: Measure temperature at the vertical halfway mark on the side of the pan; ideal oil temperature is between 180°F and 220°F.
Thrust bearing, if equipped: Each manufacturer has its own protocol for maximum allowable temperature. Generally, anything over 165°F is an indication of a problem.
Finally, engine room checks aren’t very useful if they aren’t carried out regularly. While you can’t check this space too often, doing so once every hour or two makes it likely that you’ll identify problems before they become critical.