Crankshaft Sprocket; Removal; Installation; Checking Timing Chain Deflection - Mercury MerCruiser MCM 454 Mag MPI Service Manual

SERVICE MANUAL NUMBER 23

Crankshaft Sprocket

Removal

1. Remove torsional damper and crankcase front cover as outlined.
2. Remove camshaft timing chain as outlined.
3. Remove crankshaft sprocket using crankshaft gear and sprocket puller (J-24420-B).

Installation

1. Using crankshaft gear and sprocket installer, as shown, install sprocket on crankshaft.
2. Install timing chain as outlined.
3. Install crankcase cover and torsional damper as outlined.

Checking Timing Chain Deflection

With timing chain and sprockets installed, check timing chain deflection, as follows:
1. Rotate camshaft (in either direction) to place tension on one side of the chain.
2. Establish a reference point on the block (on taut side of chain) and measure from this
3. Rotate camshaft in the opposite direction to slacken the chain, then force chain out with
4. The deflection is the difference between these two measurements. If the deflection
5. Install torsional damper and crankcase front cover.
Index
90-861326--1 MARCH 1999
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a - Crankshaft Gear And Sprocket Installer (J-1058-20)
point to the chain.
fingers and again measure the distance between reference point and timing chain.
exceeds 3/4 in. (19 mm), timing chain should be replaced.
a - Reference Point
a
a
454 CID (7.4L) / 502 CID (8.2L)
72550
72946
Page 3A-77