FAN AS 3998500 - Caterpillar

the temperature of the oil that is in the oil gallery. The maximum oil temperature that is allowed for this engine is 110 °C (230 °F). If the temperature of the engine oil is high, inspect the engine for the following causes.Check for problems that could cause high cylinder temperatures. Inspect the engine for the possible causes of high cylinder temperatures:
Restriction in the air inlet system
Restriction in the exhaust system
Faulty fuel injector (misfiring cylinder)Note: Excessive lugging of the engine can also cause high cylinder temperatures. Be sure to evaluate engine operation as a contributor to a complaint of increased oil temperature.Check for high cooling system temperatures. Inspect the engine's cooling system for the possible causes of high cooling system temperatures:
Restriction in the coolant system
Restriction of coolant flow in the oil cooler
Not enough coolant in the coolant system
Loose fan drive beltCheck for problems with the engine's lubrication system. Inspect the engine for possible problems with the engine's lubrication system:
Restriction of the oil cooler oil flow
Engine oil cooler bypass valve that is sticking
Incorrect oil level in the oil pan