The Thermo King Alarm 18 can be described in the following table:
| Alarm 18 Thermo King | |
|---|---|
| Yellow. High temperature of the diesel engine coolant. | |
| If the unit shuts down, repair immediately. Otherwise, report the alarm at the end of the day. |
The microprocessor utilizes the engine coolant temperature sensor to monitor its temperature. If the coolant temperature rises above an acceptable level, the microprocessor records alarm codes 41 and probably 18. The microprocessor may also shut down the unit.
Fault Code 18 Thermo King:
A high coolant temperature could cause the engine to overheat in a shorter period than usual.
- Check for low coolant level or leaks.
- Start by inspecting the Thermo King equipment thermostat.
- The thermostat may be faulty or covered in dirt; it should be cleaned and checked for recurring errors.
- Check if the water pump is functioning correctly.
- Pressure wash the radiator if necessary.
- A dirty radiator can hinder air circulation, leading to overheating.
- Verify if the motor oil is at its usual level.
- Check if the oil has its normal consistency; diesel can mix with engine oil in case of leaks.
How the Engine Cools:
The diesel engine cooling system transfers heat generated by combustion and friction to the environment. The system includes engine coolant, propelled by the water pump, driven by the diesel engine.
Once the engine coolant has traversed all spaces and equalized the engine temperature, the mixture of water and coolant significantly increases in temperature. It is then transported to the engine radiator.
The radiator, typically made of aluminum, consists of channels that aid in cooling the liquid flowing through the ducts. Hot water enters the radiator from one reservoir and must pass to the other reservoir through small panel ducts, transferring heat to cooler surroundings. The air from driving passes through the panel on the exterior of the ducts, collecting heat and lowering its temperature.
- Support.
- Fuel injection line.
- Cylinder head cover.
- Exhaust manifold.
- Water pump.
- Gearbox cover.
- Crankshaft pulley.
- Oil sump.
- Oil level switch.
- Level rod.
- Oil filter.
- Fuel injection pump.
- Air intake.
What to Do with Alarm 18:
- Verify if Alarm 18 is a result of genuine overheating or a false reading.
- Diesel engines are designed to operate in a temperature range between 80°C and 100°C. The cooling system’s function is to maintain the temperature within this range for optimal engine performance.
- Check the liquid coolant level and eliminate possible leaks.
- If the equipment’s thermal load (products) is too high, the cooling circuit pressure increases, causing the diesel engine to exert more effort, leading to overheating.
- To check engine overheating, use a thermometer pointing at the thermostat box, at the temperature switch or sensor location, and verify temperature values.
- If the temperature is correct, then check the temperature sensor and connections causing the erroneous Alarm 18.
- If the engine temperature is indeed high, check the water pump and radiator fan belts.
- Verify if the cooling system operating pressure is excessive (some systems or above 7 psi (48 kPa)).
- Check the radiator for airflow obstructions or damaged fins.
- Check temperatures above and below the thermostat; it should be open at 160 to 190 F [71-88 C].
- Verify thermostat operation by checking for a significant temperature differential indicating a stuck-closed thermostat.
- Use a thermometer to check temperatures at the radiator inlet and outlet. The differential should be greater than 25 F (14°C).
- Clean the radiator if the temperature differential between the inlet and outlet is low.
- Rule out internal hose obstructions as they can collapse, causing a restriction while the engine is running. Hoses can also internally degrade, restricting the flow of diesel engine coolant.
- Thermostat housing.
- Gasket.
- Thermostat 180 F (82 C).
- Gasket.
- Water pump.