SWITCH GP 8U9568 - Caterpillar

Problem 8: Engine Overcooling
Probable Cause
Long Idle Periods - When the engine is running with no load, only a small quantity of fuel is burned. Therefore, the heat from the engine is removed too fast. The check valve in the vent line may be missing, or the orifice in the vent line may be missing. When the check valve or the orifice is missing, too much heat is removed from the engine.Very Light Load - Very light loads or a very slow engine speed can cause overcooling. This overcooling is caused by the low heat input of the engine. The installation of shutters helps to correct this condition.Faulty Water Temperature Regulator (thermostat) - A regulator that is stuck open can cause overcooling. Overcooling also occurs when the water temperature regulator is stuck between the following positions: open position and closed position. Coolant leaks that are around the water temperature regulator can cause overcooling. An example would be a vent line leak.Problem 9: Coolant Leaks Outside Of Engine
Probable Cause
Leaks In Hoses Or Connections - Check all hoses and connections for visual signs of leakage. If no leaks are seen, look for damage to hoses or loose clamps.Leaks In The Radiator And/Or Expansion Tank - Apply pressure to the radiator or the expansion tank with the 9S-8140 Pressurizing Pump. Check for leaks. Refer to Testing And Adjusting, "Testing Radiator And Cooling System For Leaks".Leaks In The Heater - Apply pressure to the radiator or to the expansion tank with the 9S-8140 Pressurizing Pump. Check for leaks. Refer to Testing And Adjusting, "Testing Radiator And Cooling System For Leaks".Leaks In The Water Pump - Check the water pump for leaks before starting the engine. Start the engine and look for leaks. If the water pump leaks, repair the water pump or install a new water pump.Cylinder Head Gasket Leakage - Look for leaks along the surface of the cylinder head gasket. Install a new head gasket if leaks are visible.Problem 10: Coolant Leaks At The Overflow Tube
Probable Cause
Faulty Pressure Cap Or Relief Valve - Check the sealing surfaces of the pressure cap and the radiator.