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

Water Pump Impeller Disassembly/Assembly
Water Pump Housing DisassemblySeat Cutter Operation Care
1. This valve seat cutter is developed to grind the valve for
repair. Therefore the cutter must not be used for other
purposes than seat repair.
2. Do not drop or shock the valve seat cutter, or the diamond
particles may fall off.
3. Do not fail to apply engine oil to the valve seat cutter
...
Check 3-7 Stop Watch Inspection
Connect the leads in the same circuit as Check 3-2.
By pushing the upper button each time to set the stop
watch mode.
Connect the insulated auxiliary lead processed insulation
to the terminal [13] as shown in the figure, then stop watch
start to count.
While count the stop watch, conn ...
Refreshing Charge
Remove the battery (see Battery Removal).
Do refresh charge by following method according to the
battery terminal voltage.
WARNINGThis battery is sealed type. Charge with
current and
time as stated below.
Terminal Voltage: 12.0 12.7
V
Standard Charge (see following ...