If any one of the parts is damaged, replace the mechanical seal as a unit.
Rubber Seal [A] Mechanical Seal [B]

Water Pump Housing Assembly
RadiatorStarter Motor Disassembly
Remove the starter motor (see Starter Motor Removal).
Take off the starter motor through bolts [A] and remove
the both end covers [B].
Pull out the armature [A] out of the yoke [B].
NOTE
Do not remove the circlip [C] from the shaft.
Remove the starter motor terminal lock ...
Radiator and Cooling Fan
Check the radiator fins for obstruction
by insects or mud. Clean off
any obstructions with a stream of
low-pressure water.
WARNINGThe cooling fan spins at high
speed and can cause serious
injuries. Keep your hands and
clothing away from the cooling
fan blades at all times.
...
Air Switching Valve (Service Code 64)
Air Switching Valve Removal/Installation
Refer to the Air Switching Valve Removal/Installation in
the Engine Top End chapter.
Air Switching Valve Inspection
Refer to the Air Switching Valve Unit Test in the Electrical
System chapter.
If the air switching valve [A] is normal, check ...