TUBE AS 2786612 - Caterpillar

Damage of the components or a fire may be caused if the coolant overheats due to any reasons. Two types of overheating protection devices are fitted as fail-safe equipment. One is the thermostat for overheating protection, and the other is the thermo-fuse for dry heating protection.Action when the thermostat for overheating protection activated.
The electrical system opens the solenoid valve circuit to stop fueling by activating the thermostat for overheating protection when the temperature of the engine coolant exceeds 95 degrees C. Simultaneously when the thermostat for overheating protection activates, the OVERHEAT warning light (red) comes on for quick notification to the operator of overheating. Immediately turn the operation switch back to the OFF position (the engine pre-warmer stops completely when the RUN indicator light goes out in 3 to 5 minutes). Check the following items if the OVERHEAT warning light comes on before the temperature of the engine coolant reaches the operating temperature (check with the engine coolant temperature gauge).1 Check that all valves in the hot water circuit are fully opened. Check that any section of the piping does not have high resistance.2 Check that air is not trapped in the hot water channel. Check that the engine is not in dry heating condition.3 Check that the engine pre-warmer is not operating at low temperature due to malfunction of the thermostat (temperature control).Action when the thermo-fuse activated.
The electrical system opens the solenoid valve circuit to stop fueling by melting down the thermo-fuse when the temperature around the thermo-fuse reaches approximately 100 degrees C. Replace the thermo-fuse according to the following procedure. 1. First turn the operation switch back to the OFF position.2. Investigate and correct the cause of thermo-fuse meltdown. (Check that air is not trapped in the heat exchanger, the engine is not heated dry).3. The thermo-fuse can be removed from the housing by unscrewing 2 setscrews. Replace the thermo-fuse as shown in the fig. (Confirm the thermo-fuse is for 100 degrees C).4. Operate the engine pre-warmer again after investigating the cause of overheating and replacing the thermo-fuse. However, do not substitute the thermo-fuse with one of higher temperature or a steel wire because the thermo-fuse is important fail-safe equipment.