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Exclude the thermostat problem, this part is broken will also lead to Shangchai generator overheating

July 11, 2022
A diesel generator set recently overheated while generating electricity, the fault appeared suddenly, the problem may be in the thermostat. But after checking, the thermostat was fine. So what is the cause of this Shangchai diesel generator overheating?
Diagnosis: If the engine has overheated and the fault appears quickly, there may be a problem with the radiator cap. If the radiator cap can not maintain the pressure of the cooling system. Then the Tao point will be lowered. This may lead to overheating of the engine.
A very common cause of diesel generator sets overheating is a bad radiator pressure cap. The radiator pressure cap is used to maintain the cooling system pressure and when the cooling system pressure increases, the boiling point of the coolant also increases. If the cooling system pressure decreases (a bad radiator pressure cap), the boiling point also decreases. Check the pressure cap using a pressure cap and cooling system tester. If the radiator pressure cap does not maintain the cooling system pressure, the tester will make a sound.
Repair method: Check the radiator cap using the following procedure, taking care to make sure the cooling system is at room temperature before starting work.
(1) Remove the radiator cap
(2) Place the pressure cap on the pressure tester as shown in Figure 1-1. Turn the pressure cap to seal it on the pressure tester as you would on a radiator.
(3) Use the pump on the pressure tester to increase the pressure on this cap.
(4) Make a note of the pressure at which the pressure cap begins to open. When increasing pressure with the pump, the pressure will not eventually rise any higher.
(5) Make sure that the pressure cap releases pressure when the pressure reaches the pressure setting shown on the cap.
(6) If the cap begins to release pressure when the pressure falls below this point, the cap is defective and replace the pressure cap.
(7) Also check the pressure cap vacuum valve. One method used to check the cap valve is to look at the upper radiator hose. If the upper radiator hose collapses after the engine cools, the vacuum valve may be faulty or clogged. If the valve is plugged base or damaged, it will not allow the pressure in the cooling system to equalize when it is being cooled. If this happens, replace or clean the vacuum valve to fix the problem.
Overheating of diesel generator sets will cause the power of the unit to drop and affect normal operation. Once the overheating phenomenon occurs, users should find the cause to fix it in time.