RIM AS 5406851 - Caterpillar

Water Pump Operation
Note: The following information applies to 354-4754 Water Pump Kit and 354-4755 Water Pump Kit.The water pump contains a rotary seal. The engine coolant is used to lubricate the rotary seal and maintain an adequate sealing film to reduce generation of heat. During normal operation, a small amount of coolant and vapor will pass over the seal into a chamber within the pump. The chamber allows the coolant to evaporate through the weep hole and the vent holes in the pump.In some ambient conditions and operating conditions, not all the liquid will evaporate. In this situation, the liquid may be expelled through the weep hole. A small loss of coolant from the weep hole does not necessarily indicate a fault in the pump. A small loss is one drop of coolant within 10 seconds.The rotary seal within the pump can become compromised by debris between the seal faces. Usually, the seal will expel the debris within 30 hours of operation. During this period, there may be a significant loss of coolant through the weep hole.The seal may be damaged if there is not enough coolant flow around the seal. In this situation, the leak rate from the weep hole will be greater than 1 drop in 10 seconds.Water Pump Troubleshooting
Before installing a replacement water pump, perform the following procedure:
If a coolant leak is suspected near the water pump, determine if the leak is a new event. Remove any coolant stains from the water pump and the front of the engine.
Check the coolant level. Refer to Operation and Maintenance Manual, Cooling System Coolant Level - Check.
Monitor the area around the water pump regularly for signs of a coolant leak.
Monitor the leak rate from the weep hole in the water pump. If the leak rate is greater than 1 drop in 10 seconds or if the leak does not stop after 30 hours of operation, install a replacement water pump. Refer to Disassembly and Assembly, Water Pump - Remove and Disassembly and Assembly, Water Pump - Install
Before returning the engine to service, check for the following possible causes of insufficient coolant flow to the water pump seal:
Low coolant level. Refer to Operation and Maintenance Manual, Cooling System Coolant - Change.
Maintenance Interval Schedule adherence. Refer to Operation and Maintenance Manual, Maintenance Interval Schedule
Air in the cooling system that was not purged during fill. Refer to Operation and Maintenance Manual, Cooling System Coolant - Change.
Leaks in the cooling system. Refer to Systems Operation, Testing and Adjusting, Cooling System - Inspect
High coolant temperature. For electronically controlled engines, refer to Troubleshooting, Coolant Temperature Is Too High. For mechanical engines, refer to Systems Operation, Testing and Adjusting, Troubleshooting.