Crankshaft; Removal; Cleaning And Inspection - Mercury MerCruiser MCM 454 Mag MPI Service Manual

454 CID (7.4L) / 502 CID (8.2L)

Crankshaft

Removal

1. Remove engine from boat.
2. Drain crankcase oil.
3. Remove as outlined:
a. Starter.
b. Flywheel housing.
c. Drive coupler/plate and flywheel.
d. Belts.
e. Water pump.
f.
g. Spark plugs.
h. Oil pan and dipstick tube.
i.
j.
4. Turn crankshaft to align timing mark with camshaft mark.
5. Remove camshaft sprocket or gear.
6. Remove rear main seal.
IMPORTANT: Inspect bearing caps for orientation marks prior to removal. If no mark-
ings exist, make suitable marks before disassembly so that they can be reinstalled
in their original locations.
7. Make sure all bearing caps (main and connecting rods) are marked so they can be rein-
stalled in their original locations.
8. Remove connecting rod bearing caps, then push piston and rod assemblies toward
heads.
9. Remove main bearing caps and carefully lift crankshaft out of cylinder block.
10. If new main and/or connecting rod bearings are to be installed, remove main bearing
inserts from cylinder block and bearing caps, and/or connecting rod bearing inserts from
connecting rod and caps. Install new bearings following procedures outlined.

Cleaning and Inspection

1. Wash crankshaft in solvent and dry with compressed air.
2. Measure main bearing journals and crankpin dimensions with a micrometer for
out-of-round, taper or undersize (see "Specifications").
3. Check crankshaft for runout (by supporting at front and rear main bearings journals in
V-blocks) and check at front and rear intermediate journals with a dial indicator (see
"Specifications").
4. Replace or recondition crankshaft if not within specifications.
Index
Page 3A-74
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Crankshaft pulley and torsional damper.
Baffle and oil pump.
Timing chain/gear cover.
SERVICE MANUAL NUMBER 23
90-861326--1 MARCH 1999