Series 50 – Section 27.8 Faulty Water Pump

Section 27.8
Faulty Water Pump

To determine if a faulty water pump is causing high engine coolant temperature, perform the following: ‪

1. Remove the water pump (gear case mounted); refer to "4.2.2 Draining and Removal of Water Pump" .
2. Turn the water pump over and install J 35687 , water pump impeller slip and lash tester, into the tapped holes provided in the impeller; see Figure "Measuring Water Pump Drive Gear Run-Out" .
   

   Figure 1. Measuring Water Pump Drive Gear Run-Out

3. Clamp the water pump drive gear in a vise, with the impeller facing up. Use soft jaws to prevent damage to the gear teeth.
4. Using a 1/2 in. drive torque wrench in the hole provided in the center of the slip-lash tester, apply 68 N·m (50 lb·ft) torque in either direction. The impeller must withstand 68 N·m (50 lb·ft) torque without slipping.
   1. If the torque 68 N·m (50 lb·ft) is satisfied without the impeller slipping, check combustion gases in coolant; refer to "27.9 Combustion Gases in Coolant" .
   2. If the torque 68 N·m (50 lb·ft) is not satisfied and the impeller is slipping; refer to "27.8.1 Water Pump Impeller Replacement" .

Section 27.8.1
Water Pump Impeller Replacement

Perform the following steps to replace water pump impeller:‪

1. Disassemble the water pump and replace worn or damaged impeller; refer to "4.2.3 Disassembly of Water Pump" for (gear case mounted).
2. Reassemble the water pump with new components as necessary; refer to "4.2.4 Assembly of Water Pump" for (gear case mounted).

Section 27.8.1.1
Test Engine with Repaired Water Pump

Perform the following to determine if thermo-modulated fan replacement resolved high engine coolant temperature:‪

1. Start and run the engine.
2. Run the engine through its operating range with no-load for approximately 5 minutes, allowing the engine coolant to reach normal operating range.
   1. If the engine coolant temperature is 88-96°C (190-210°F), no further troubleshooting is required. Shut the engine down.
   2. If the engine coolant temperature is not 88-96°C (190-210°F), shut the engine down. Check combustion gases in coolant; refer to "27.9 Combustion Gases in Coolant" .