Mercury 90 Manual

20
90-10122R30
GB
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MAINTENANCE
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FUSE REPLACEMENT
IMPORTANT: Always carry spare SFE 20 AMP fuses.
The electric starting circuit is protected from overload by an SFE 20 AMP fuse. If
the fuse is blown, the electric starter motor will not operate. Try to locate and
correct the cause of the overload. If the cause is not found, the fuse may blow
again.
1 Open the fuse holder and look at the silver colored band inside the fuse. If band
is broken, replace the fuse. Replace fuse with a new fuse with the same rating.
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CORROSION CONTROL ANODE
2
An anode (a) is installed on the bottom of the transom bracket assembly. Trim
tab (b) is also an anode on the 3-1/4 in. (83mm) diameter gear case. The 4-1/4
in. (108mm) diameter gear case has three anodes. One of the anodes is the
trim tab (b) and two anodes (c) are located on the side. An anode helps protect
the outboard against galvanic corrosion by sacrificing its metal to be slowly
eroded instead of the outboard metals.
Each anode requires periodic inspection especially in salt water which will
accelerate the erosion. To maintain this corrosion protection, always replace the
anode before it is completely eroded. Never paint or apply a protective coating on
the anode as this will reduce effectiveness of the anode.
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PROPELLER REPLACEMENT - 3-1/4 IN. (83MM)
DIAMETER GEAR CASE
WARNING
If the propeller shaft is rotated while the engine is in gear, there is the pos-
sibility that the engine will crank over and start. To prevent this type of
accidental engine starting and possible serious injury caused from being
struck by a rotating propeller, always shift outboard to neutral position
and remove spark plug leads when you are servicing the propeller.
1 Shift outboard to neutral (N) position.
2 Remove spark plug leads to prevent engine from starting.
3 Straighten the bent tabs on the propeller nut retainer.
4 Place a block of wood between gear case and propeller to hold propeller and
remove propeller nut.
5 Pull propeller straight off shaft. If propeller is seized to the shaft and cannot be
removed, have the propeller removed by an authorized dealer.
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PROPELLER REPLACEMENT - 4-1/4 IN. (108MM)
DIAMETER GEAR CASE
6 Coat the propeller shaft with Quicksilver or Precision Lubricants
Anti-Corrosion Grease or 2-4-C Marine Lubricant with Teflon.
IMPORTANT: To prevent the propeller hub from corroding and seizing to the
propeller shaft, especially in salt water, always apply a coat of the
recommended lubricant to the entire propeller shaft at the recommended
maintenance intervals and also each time the propeller is removed.
7 Flo-Torque I Drive Hub Propellers - Install forward thrust hub (a), propeller (b),
propeller nut retainer (c) and propeller nut (d) onto the shaft.
8 Flo-Torque II Drive Hub Propellers - Install forward thrust hub (a), propeller (b),
replaceable drive sleeve (c), rear thrust hub (d), propeller nut retainer (e) and
propeller nut (f) onto the shaft.
9 Place propeller nut retainer over pins (a). Place a block of wood between gear
case and propeller and tighten propeller nut to 55 lb. ft. (75 N·m), aligning flat
sides of the propeller nut with tabs on the propeller nut retainer.
10Secure propeller nut by bending tabs (b) up and against the flats on the
propeller nut.
11 Reinstall spark plug leads.
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4-53
1
N
N
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PROPELLER REPLACEMENT - 4-1/4 IN. (108MM)
DIAMETER GEAR CASE
WARNING
If the propeller shaft is rotated while the engine is in gear, there is the pos-
sibility that the engine will crank over and start. To prevent this type of
accidental engine starting and possible serious injury caused from being
struck by a rotating propeller, always shift outboard to neutral position
and remove spark plug leads when you are servicing the propeller.
1 Shift outboard to neutral (N) position.
2 Remove spark plug leads to prevent engine from starting.
3 Straighten the bent tabs on the propeller nut retainer.
4 Place a block of wood between gear case and propeller to hold propeller and
remove propeller nut.
5 Pull propeller straight off shaft. If propeller is seized to the shaft and cannot be
removed, have the propeller removed by an authorized dealer.

Mercury 90 Specifications

General

Brand	Mercury
Model	90
Category	Outboard Motor
Language	English