To determine if a faulty water pump is causing high engine coolant temperature, perform the
following:
1. Remove the water pump, (gear case mounted) or (gear case cover mounted); refer to appropriate service manual, cooling system chapter.
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 13-1.
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.
[a] If the torque 68 N·m (50 lb·ft) is satisfied without the impeller slipping, check
combustion gases in coolant; refer to section 13.9.
[b] If the torque 68 N·m (50 lb·ft) is not satisfied and the impeller is slipping,
refer to section 13.8.1.
13.8.1
Water Pump Impeller Replacement
Perform the following steps to replace water pump impeller:
1. Disassemble the water pump and replace worn or damaged impeller for (gear case mounted) or (gear case cover mounted); refer to appropriate service manual, cooling system chapter.
2. Reassemble the water pump with new components as necessary for (gear case mounted) or (gear case cover mounted); refer to appropriate service manual, cooling system chapter.
13.8.1.1
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.
[a] If the engine coolant temperature is 88-96°C (190-210°F), no further troubleshooting
is required. Shut down the engine.
[b] If the engine coolant temperature is not 88-96°C (190-210°F), shut down the engine.
Check combustion gases in coolant; refer to section 13.9.
