Mercury 25 EFI Service Manual page 30

Maintenance
3. Remove the spark plug leads to prevent the engine from starting.
4. Remove the six screws securing the water intake housing, and remove the water intake housing.
5. Straighten the bent tabs on the impeller nut retainer and remove the impeller nut.
b
6. Pull the impeller straight off the shaft. If the impeller is tight, use a hammer and a block of wood to rotate the impeller
clockwise on the shaft until the keyway is directly above the flat on the shaft. This will free the jammed key and allow
removal.
Installation
1. Lubricate the driveshaft, shear key, and impeller bore.
2. Place the plastic sleeve inside the impeller and install impeller, shear key, shims, nut retainer, and impeller nut.
3. Turn the nut tight on the shaft to remove any play between the impeller and shaft. If the tabs on the retainer do not line up
with the flats on the nut, remove the nut and turn the retainer over and tighten the nut again.
Page 1B-16
a - Tabs
b - Impeller nut
a
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a - Plastic sleeve
b - Impeller
c - Shear key
d - Shims
e - Nut retainer
f - Impeller nut
a
b
c
d
e
f
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© 2016 Mercury Marine
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90-8M0105568 eng MARCH 2016