Mercury 25 EFI Service Manual page 425

3. Remove the impeller and drive key from the driveshaft.
a
b
4. It is recommended that the impeller be replaced whenever the gearcase is being serviced.
NOTE: If the impeller is not going to be replaced, do not install the impeller in reverse rotation to its original state as the
vanes have taken a set. The vanes will crack and break shortly after the outboard is returned to service.
5. Remove the water tube grommet from the pump cover. Inspect the grommet for wear or damage. Replace the grommet as
required. When installing the grommet into the pump cover, align the grommet tabs with the holes in the pump cover.
6. Inspect the pump cover for damage from excessive heat ‑ charring, blistering or discoloration. Replace the cover as
required.
c
a
7. Remove the water pump cover gasket.
a
IMPORTANT: The circular groove formed by the impeller sealing bead should be disregarded when inspecting the liner
and face plate. The depth of the groove will not affect the water pump output.
90-8M0105568 eng MARCH 2016
a - Water pump cover
b - Grommet
b
c - Tabs
d - Holes
d
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© 2016 Mercury Marine
a - Impeller
b - Drive key
21037
a - Water pump cover gasket
Gear Housing
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