System Components; Periodic Maintenance; Drive Belt Tension Adjustment - Mercury MerCruiser MCM 454 Mag MPI Service Manual

SERVICE MANUAL NUMBER 23

System Components

The alternator system consists of the alternator, battery, the ignition switch and the wiring
which connects these components. Refer to wiring diagrams in SECTION 4E.

Periodic Maintenance

Remove all battery cables from battery (before conducting the following check) to
prevent accidentally shorting out electrical system.
1. Inspect entire alternator system for corroded or loose connectors.
2. Check wiring for frayed or worn insulation.
3. Check alternator drive belt for excessive wear, cracks, fraying and glazed surfaces.
4. Check alternator mounting bolts for adequate tightness.
5. Inspect slip ring end frame flame arrestor screen for debris and clean, if necessary, using

Drive Belt Tension Adjustment

1. Install drive belt on pulleys and adjust tension as follows:
IMPORTANT: If a belt is to be reused, it should be installed in the same direction of
rotation as before.
1. Remove drive belt as follows:
NOTE: The upper, right (starboard) idler pulley is the belt adjustment pulley.
2. Install drive belt on pulleys and adjust tension as follows:
3. Loosen 5/8 in. locking nut on adjustment stud. Leave wrench on adjustment stud.
NOTE: Belt deflection is to be measured on the belt at the location that has the longest
distance between two (2) pulleys. Normally this location is between the power steering
pump and the belt adjustment pulley. This location will be different on engines with closed
cooling or models without power steering.
4. Use 5/16 in. socket and tighten adjusting stud until the correct deflection of the belt is
Index
90-861326--1 MARCH 1999
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Also, check drive belt tension and adjust, if necessary, as explained under "Drive Belt
Tension Adjustment," following.
compressed air or a cloth. Screen MUST BE clean, or alternator may overheat.
a. Loosen 5/8 in. locking nut on adjustment stud.
b. Turn adjustment stud and loosen belt. Remove belt.
obtained at location specified above.
CAUTION
CHARGING SYSTEM
Page 4C-7