28 March 2026

High water temperature of diesel engine will usually cause boiling coolant in the radiator , the power
decreases, the viscosity of the lubricating oil decreases, the friction increases, and even cause the diesel
engine to pull the cylinder and cylinder head gasket burned.
Below are main reasons for the high temperature of the diesel engine and preventions and improvements
● Diesel engine long time overload operation will increase fuel consumption and heat load, resulting in wa
high temperature.So please avoid long time overloaded operation.
● Please check the coolant stock in the radiator and expansion tank, and replenish it in time when the liqu
level is low. Because lack of coolant will affect the heat dissipation effect , and resulting in high temperatu
of the diesel engine.
● If the hydraulic oil radiator and the water radiator are placed in tandem, when the temperature of the
hydraulic oil is high, the temperature of the cold air on the air inlet side of the water radiator will be high,
which will affect the heat dissipation of the water radiator. In this regard, the heat dissipation of the hydrau
system should be overhauled to reduce the influence of the hydraulic oil radiator on the poor heat dissipat
of the water radiator of the diesel engine. 

● Please check whether the fan belt is loose and whether the fan shape is abnormal.If the fan belt is too lo
it is easy to cause the fan speed to decrease, causing the radiator cannot play the due heat dissipation
capacity, and resulting in excessive diesel engine temperature. In addition, the deformation of the fan will
cause the heat dissipation capacity of the radiator to not be fully fulfilled.
● The radiator surface attached debris is the most common phenomenon, the attached debris will reduce
radiator cooling area, the windward area of the radiator, resulting in the heat dissipation capacity of the
radiator, causing high temperature of diesel engine.Therefore, the radiator should be cleaned regularly.
● Insufficient opening of the thermostat will reduce the heat dissipation capacity of the large cycle of the
engine cooling system. If the engine is hot, you can put the thermostat in the water for heating inspection
Generally, the opening distance of the thermostat is 8-10mm.
(Kindly Reminder：Poor performance of the water pump will reduce the coolant flow rate and cause the
diesel engine to become hot.)
● In this regard, check the upper and lower water chambers of the radiator. The temperature difference
between the upper and lower water chambers is generally 6-12°C. If it is too small, the water pump can be
replaced.Too much scale will also affect the heat dissipation efficiency of the fins in the radiator and reduc
the thermal conductivity of the coolant and the cold air. In this regard, the diesel engine cooling system
should be cleaned regularly, and at the same time, avoid using inferior coolant to reduce the generation of
scale.