If the surface is corroded or if the blades are damaged, replace the impeller

Water Pump Impeller Disassembly/Assembly
Water Pump Housing DisassemblyPiston Wear Inspection
Measure the outside diameter [A] of each piston 5 mm
(0.20 in.) [B] up from the bottom of the piston at a right
angle to the direction of the piston pin.
If the measurement is under service limit, replace the piston.
Piston Diameter
Standard: 75.959 75.974 mm
(2.9905 2.9911 in.)
...
Oil Pump Drive Gear Installation
Install is the reverse of removal. Note the following.
First, engage the oil pump chain [A] to the gears, and then
install the oil pump drive gear [B].
Turn the “OUT” mark [C] to outside.
Apply a non-permanent locking agent to the oil pump drive
chain guide bolt and the oil pump drive ...
Ball Bearing and Needle Bearing
Do not remove pressed ball or needle unless removal is
absolutely necessary. Replace with new ones whenever
removed. Press bearings with the manufacturer and size
marks facing out. Press the bearing into place by putting
pressure on the correct bearing race as shown.
Pressing the incorrect ra ...