293
GEARCASE
GEARCASE TYPES, 75 – 90 HP
12
GEARCASE TYPES, 75 – 90 HP
PROPELLER SERVICE
Inspection
Carefully examine p ropeller and o utboard f or the
following:
• Damaged blades and sign s of pro peller cavita-
tion (burned paint, etc.)
• Spun or overheated inner hub
• Worn or twisted spline s and ina dequate lub ri-
cant
• Damaged or missing converging ring (if applica-
ble)
• Damage to outer hub area
• Worn, missing, or incorrect thrust washer and
spacer
• Correct size and style
• Check for ben t or damaged propeller shaft and
twisted splines.
Refer to Propeller Hardware Installation on
p. 294.
Propeller Selection
Water testing with various p ropeller designs an d
sizes is the best method of propeller selection.
The co rrect propeller, und er no rmal lo ad condi-
tions, will allow the engine to run near the mid-
point of the RPM oper ating range at full throttle.
Refer to SERVICE SPECIFICATIONS on p. 10.
If the propeller blades have too
much pitch, the engine will operate below its
normal range at full throttle. Power will be lost,
and powerhead damage could occur. If the
propeller blades have too little pitch, the
engine will operate above its normal range and
damage from overspeeding could occur.
Outboard Model
Gearcase
Type
General
Comparison
Service Procedure
Comparison
(L) Models with
20 in. shaft
“S”
Unique housing, shafts,
gears, and bearings
Similar
(X) Models with
25 in. shaft
“O”
Unique housing, shafts,
gears, and bearings
A WARNING
When servicing the propeller, always shift
the outboard to NEUTRAL, turn the key
switch OFF, and disconnect the battery
positive (+) cable so the outboard cannot
be started accidentally.
A CAUTION
Selection of the wrong propeller could
reduce engine service life, affect boat per-
formance, or cause serious damage to the
powerhead.
008329
30%
40%
50%
60%
70%
80%
90%
100%
2000 3000 4000 5000 6000
Operating Range
Peak HP
H
o
r
s
e
p
o
w
e
r
RPM
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