Yamaha T8 Rigging Manual page 92

Outboard Rigging Guide - 2001
If you have trouble locating these impellers
on the market, contact your dealer.
Some calls have been received regarding dif-
ficulty removing the impeller. The impeller
doesn't corrode with the shaft because there is
a delrin sleeve separating them. What can
happen, however, is that the driving torque
causes the flat on the shaft to "cam" or wedge
the key in the impeller.
To relieve this wedging, rotate the impeller
on the shaft until the keyway in the impeller
is perpendicular to the flat on the shaft. This
can be done with a soft hammer on a block of
wood, or by using a C-clamp on one blade
and bumping the clamp.
The impeller is now free to pull it. If neces-
sary, use two wood levers, about 3/4" x
1-1/2" x 12", wedged under the blades against
the housing flanges to assist with removing
the impeller.
9. Some larger displacement jet drives have
experienced a performance problem above
4500rpm up to 5500rpm. On affected units,
there may be little or no change in boat speed,
only more noise. What may be happening is
impeller cavitation. This can happen if the
impeller liner is pushed too far into the foot.
Look up into the jet from the bottom of the
foot. If the liner is pushed too far in, there is
a lip that the water must go around. To correct
the problem, remove the grates and grind
down this lip to make a smooth path for the
water.
Jet Drive Eng. Mtg., Maintenance,
Shift Cable Instruction, Service Info.
Overhaul Procedures
NOTE: It is recommended that these procedures
be performed by only your authorized Yamaha
Outboard Motor Dealer.
Disassembly
Refer to "Assembly and Installation" (page 2-23),
and reverse the procedures outlined here.
Bearing Housing
1. Remove the large beveled circlip from the
bearing housing. Gently warm the housing
with a torch until it is just too hot to comfort-
ably touch.
CAUTION:
Do not apply too much heat because the seals
may be damaged.
2. Holding the driveshaft vertically, bump the
impeller end of the shaft against a wooden
block until the housing slides down off the
bearings.
3. Note the direction of thrust faces of the bear-
ing(s), and press the bearing(s) off the drive-
shaft. Leave the round thrust ring on the shaft
unless it is damaged. Remove the seals from
the bearing housing and upper seal housing.
Clean all parts thoroughly and remove all
burrs.
NOTE: The inner seals are located on both sides
by spiral seal-retaining rings that must be
removed prior to extraction of the inner seals.
4. FOR 40 AND 50 MODELS ONLY:
Before pressing on the collar, first, install the
coated thrust washer with the gray Teflon
coating facing the bearing. Note the direction
of the thrust face, and press the new bearing
onto the shaft, pressing against the inner race
only. Press against the thrust ring, locking it
in its groove.
FOR 90 AND V4/V6 MODELS ONLY:
Using Yamaha special tool #YB-06075, note
2-29