2009/09/30 Water Pump Operation {1361, 7555} Caterpillar

The 322-9662 Water Pump Gp and 307-9843 Water Pump Gp contains a rotary seal that uses the engine coolant as a lubricating medium. This will ensure that an adequate sealing film is created and maintained in order to reduce heat generation.

During normal operation, the seal on the shaft in the water pump will allow a small amount of coolant and vapor to pass over the seal into a chamber area. The chamber area allows coolant that is expelled over the seal to evaporate. The vapor will exit out of the weep hole. In certain environmental conditions and operating conditions, not all of the liquid will be evaporated. If the coolant is unable to evaporate from the chamber the coolant may be expelled from the weep hole. A small amount of coolant from the weep hole is not a failure of the seal. In normal pump operation, a small loss of coolant from the weep hole will occur. A small loss of coolant will be one drop of coolant within a ten second period.

The seal faces can become damaged by debris. The seal will repair any damage within thirty hours of the event in most cases. Coolant level should be regularly checked during this period.

If there is severe damage to the seal on the shaft of the water pump a significant amount of coolant will be lost through the weep hole.

If a coolant leak is discovered near the water pump, it is important to determine if the coolant leak is a new event. Remove the stain from the water pump. Remove the stain from the front of the engine. Check the coolant level. Check the area regularly for signs of a continued leak.

Nonfixable damage to the seal can occur when there is insufficient coolant around the seal. This increases the rate of weep. The leak rate will be more than one drop of coolant within a time of ten seconds. If the leak rate will be more than one drop of coolant within a time of ten seconds or the leakage does not stop after thirty hours, a service engineer should make a more detailed investigation.

The following situations can cause cooling fluid starvation problems around the seal:

• Low coolant level

• Inadequate maintenance

• Air that has not been removed from the coolant system on initial fill

• Leaks within the cooling system

• Boiling of the coolant

Cooling fluid boiling will introduce air pockets into the coolant system. Boiling of the coolant can be caused by the following situations:

• Pressure leak from the cooling system

• Incorrect Glycol concentration

• Restricted air flow around the cooling system

• Restricted cooling fluid flow through the thermostat

In order to maintain the cooling system, refer to Operation and Maintenance Manual for the correct procedures.