Yamaha F2.5C, Service Manual, Page: 43 / 184

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Changing the gear oil
1. Tilt the outboard motor up slightly.
2. Place a drain pan under the drain screw
1
, remove the drain screw, then the
check screw
2
and let the oil drain com-
pletely.
3. Check the oil for metal and discoloration,
and its viscosity. Check the internal parts
of the lower case if necessary.
4. Insert a gear oil tube or gear oil pump
into the drain hole and slowly fill the gear
oil until oil flows out of the check hole and
no air bubbles are visible.
5. Install the check screw and quickly install
the drain screw.
Checking the lower unit for air
leakage
1. Remove the check screw
1
, and then
install the special service tool.
2. Apply the specified pressure to check
that the pressure is maintained in the
lower unit for at least 10 seconds.
CAUTION:
Do not over pressurize the lower unit, oth-
erwise the oil seals can be damaged.
NOTE:
Cover the check hole with a rag when remov-
ing the special service tool from the lower
unit.
3. If pressure drops below specification,
check the drive shaft and propeller shaft
oil seals for damage.
Checking the propeller
1. Check the propeller blades and splines
for cracks, damage, or wear. Replace if
necessary.
Recommended gear oil:
Hypoid gear oil
SAE: 90
Oil quantity:
320 cm
3
(10.8 US oz, 11.3 Imp oz)
Leakage tester: 90890-06840
Lower unit holding pressure:
100 kPa (1.0 kgf/cm
2
, 14 psi)
Control system / Bracket / Lower unit