SWITCH-NEUTRAL 8T8653 - Caterpillar

After the engine has been started for three minutes, the engine coolant temperature exceeds 108 °C (226 °F) for more than four seconds.System Response:The Electronic Control Module (ECM) logs the event. The ECM will derate the engine power by 12.5 percent for each degree celsius above 108 °C (226 °F). The maximum derate is 25 percent of full power. The ECM will restore full engine power when the engine coolant temperature falls to 106 °C (223 °F) for 20 seconds.Possible Performance Effect:
Low powerTroubleshooting:Test Step 1. Check the Engine
Check the cooling system for problems.
Verify that the cooling system is filled with coolant to the proper level. If the coolant level is too low, air may be allowed to enter the cooling system. Air in the cooling system will cause cavitation and a reduction in coolant flow.
Check the quality of the coolant. Refer to the Operation and Maintenance Manual for coolant recommendations.
Check for air in the cooling system. Air can be introduced into the cooling system in different ways. The most common cause of air in the cooling system is the improper filling of the cooling system. Refer to the Operation and Maintenance Manual for the proper filling procedure for your engine.The next likely cause is combustion gas leakage into the cooling system. Combustion gas can be introduced into the cooling system through damaged liner seals, cracks in the liners, a damaged cylinder head, or a damaged cylinder head gasket.
Check the cooling system hoses and clamps for damage. Clamps that are damaged and hoses that are leaking can usually be discovered during a visual inspection.Hoses that have no visual leaks can soften during operation. The soft areas of the hose can kink or the soft areas of the hose may collapse during operation. This can restrict the coolant flow. This can cause the engine to overheat. Check the hoses for soft spots.Internal cracks can also develop in cooling system hoses. This type of deterioration usually produces particles that can build up in the cooling system. This may cause a restriction in the coolant flow through components. Check the hoses for spots that are hard or brittle.
Check the water pump. Remove the water pump and check for damage to the impeller. A water pump with a damaged impeller will not pump an adequate amount of coolant through the system.
Check the operation of the water temperature regulator. A water temperature regulator that does not open, or a water temperature regulator that only opens part of the way can cause overheating.
If the cooling system for this application is equipped with an expansion tank, check the shunt line for the expansion tank. The shunt line must be submerged in the expansion tank. If the shunt line is not submerged, air will be introduced into the cooling system.Check the shunt line for a restriction. A restriction of the shunt line from the expansion tank to the inlet of the water pump will cause a reduction in water pump efficiency. A reduction in water pump efficiency