Mercury 15 EFI FourStroke, Service Manual

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3. Remove the lockwasher, belt guide, timing gear, and timing gear key from the crankshaft.
a - Crankshaft
b - Nut
c - Lockwasher
d - Belt guide
e - Timing gear
Thermostat and Exhaust Cover Removal
1. Remove the oil filter. Be certain to wipe up any spills, and dispose of oil, filter, and oil‑soaked rags according to local
regulations.
2. Remove the two screws securing the thermostat cover and electrical bracket.
3. Remove the engine coolant temperature sensor.
4. Remove and inspect the anode. Discard and replace, if it is corroded 50% or more.
5. Remove the five exhaust cover screws. Remove the exhaust cover.
6. Remove the oil pressure switch.
a - Oil filter
b - Thermostat cover/electrical
bracket mounting screws
c - Engine coolant temperature
sensor
d - Cylinder head assembly
e - Anode
f - Exhaust cover
g - Oil pressure switch
7. Remove the cylinder head assembly. Refer to
Section 4B
‑
Cylinder Head Removal
.
8. Inspect the water cooling passages in the block and the exhaust cover for debris.
a
b
c
d
e
63944
63992
a
c
b
d
e
f
g
Cylinder Block/Crankcase
90-8M0125265 eng NOVEMBER 2017 © 2018 Mercury Marine Page 4A-13