I have not to date ever seen a multi cylinder diesel later model engine after 1960 without a thermostat, back then is when diesels first became the engines of choice in every thing from earth moving, trucking, farming and stationary motors Generators and irrigation pumps , mind you I have replaced thermostats where some goose had removed them in places like the Simpson desert to the high snow country, Even big Air cooled diesels have some sort of thermostatically controlled air baffles /vents or fans to maintain constant running temps .
These days most professional diesel service centers use regular oil sampling mostly for engine warranty reasons, Cat do it some times for free for research on their bigger engines, oil sampling will tell if an engine has been running hot or cold or other issues that might become a problem in the future, the oil tells the story. computers can tell lies.
The very first things to be inspected if an engine has been running hot are you guessed it, the thermostat and radiator or cooling system pressure, simplest bits first.
These days most professional diesel service centers use regular oil sampling mostly for engine warranty reasons, Cat do it some times for free for research on their bigger engines, oil sampling will tell if an engine has been running hot or cold or other issues that might become a problem in the future, the oil tells the story. computers can tell lies.
The very first things to be inspected if an engine has been running hot are you guessed it, the thermostat and radiator or cooling system pressure, simplest bits first.