Thermostat; Removal - Mercury MerCruiser MCM 454 Mag MPI Service Manual

CLOSED COOLED (FRESH WATER) MODELS

Thermostat

Removal

NOTE: If coolant flow is restricted or fails to occur, a wire should be repeatedly inserted into
all drain holes to ensure there are no obstructions in passages. Remove petcock, if neces-
sary, to insert wire completely into drain hole.
1. Drain engine block by removing drain plug. Be sure to drain both port and starboard
sides.
Starboard Side Shown (Port Side Similar)
2. Disconnect hoses from thermostat cover.
3. Remove thermostat cover attaching bolts and lockwashers, then remove cover and
gasket.
4. Remove thermostat from thermostat housing.
Index
Page 6B-10
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a - Hose
b - Drain Plug In Exhaust Manifold Elbow
a
a - Thermostat Housing
b - Thermostat
c - Gasket
d - Thermostat Housing Cover
a
b
c
d
SERVICE MANUAL NUMBER 23
74130
75746
90-861326--1 MARCH 1999