Cooling System Filling Procedure Caterpillar

Problem:

The engine cooling and bus heater systems can be difficult to fill properly. Incorrectly filling the engine cooling system can leave air trapped in the system, causing loss of engine water pump flow and engine overheating. In severe cases, cylinder head gasket failure and piston seizure can result.

Solution:

This situation is under investigation. Until a permanent solution is found, follow this fill procedure (provided by Thomas Bus):

1. Open all gate valves.

2. Open the drain cock on top of the engine.

3. Open the valve on the front heater using the heater controls.

4. Remove the radiator cap.

5. With the engine NOT running, turn the heater booster pump ON.

6. Monitor the outlet of the drain cock.

7. Add coolant as required.

8. When all air is purged (indicated by a steady stream of coolant flowing from the drain cock), close the drain cock.

9. The total volume of coolant added should be 2 to 2 1/2 gallons if the heater circuit is being filled. (If both the engine and heater systems are being filled, the capacity is 4 1/2 gallons.)

10. Start the engine and add coolant as required.

11. Install the radiator cap.

After the vehicle has been placed in service, monitor the coolant level frequently and top off as required.

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