MAINTENANCE OF COOLING SYSTEM
SECTION I. WATER PUMP AND WATER PUMP DRIVE
Water is circulated by a centrifugal water pump mounted on the right bank side of the block. The pump is driven
by an idler gear from the crankshaft.
Coolant flows from the water pump volute into the center of the V cylinder block, then around lubricating oil
cooler elements. The center of the "V" serves as a water distribution manifold to supply a flow of coolant through
the aftercooler elements and around cylinder liners.
From the liner area, the coolant flows into individual cylinder heads through passages between valves and
around injector "wells". From the cylinder heads coolant flows to the rocker housing (water outlet manifold) then
to the thermostat housings. At the thermostat housings, coolant is returned to the water pump via a bypass tube
until engine coolant temperature activates the thermostats. Coolant flow is then directed through the radiator.
Coolant circulated through the aftercooler is also returned into the thermostat housings.
7-2. WATER PUMP DISASSEMBLY. See Figure 7-1.
Remove water pump in accordance with paragraph 4-54 of the Operator and Organizational Maintenance
Remove the capscrew (1) holding the impeller on the shaft. Use the 3375265 puller and remove the water pump
impeller (3) and pump drive key (2) from the water pump shaft (12).
Remove the large retaining ring (4).
Support the drive end of the water pump body (13) and press the bearings (9 and 10) and shaft (12) assembly
from the water pump body (13) by applying pressure to the impeller end of the shaft.
Before disassembling the bearing and shaft assembly, measure the installed diameter of the retaining ring (8) at
90 degrees to the retaining ring gap. The diameter must be 1.351 inches (34.32 mm) or less. If the diameter is
greater than 1.351 inches (34.32 mm), the retaining ring engagement is inadequate and shaft machining is
required to bring the installed retaining ring outside diameter to this measurement.
Remove the water pump seal and seat (5). Drive the water pump seal (6) and oil seal (7) from the body.
Discard the seat and seals.
Use the 3375326 bearing separator to support the outer ball bearing (9) and press the water pump shaft (12) from
Support the inner ball bearing (10) on the 3375326 bearing separator, remove the retaining ring (8), and press
the shaft from the bearing. Remove the bearing spacer (11).
7-3. WATER PUMP PARTS INSPECTION. See Figure 7-1.
Inspect the ball bearings (9 and 10). Rough or worn races indicate possible damage to the shaft diameter and
the pump body bore. Discard the bearings if damaged.
Visually inspect the water pump body (13) for cracks, corrosion, and excessive wear. Measure the body bore. If
it is larger than the maximum specifications replace the body. Maximum bore specifications are as follows:
Body bore (outer bearing): 2.8431 inches (72.215 mm) maximum.
Body bore (inner bearing): 2.4493 inches (62.212 mm).
Body bore (oil seal): 1.500 inches (38.10 mm).
Inspect the water pump impeller (3) for cracks or erosion to the extent that it will retard the coolant circulation.
Replace if damaged.
Measure the water pump impeller (3) bore and shaft diameters. There should be a minimum of 0.001 inch (0.03
mm) press-fit between the shaft and bore mating surfaces. Replace if damaged.