Inspecting; Replacing And/Or Adjusting Tension - Mercury MerCruiser MCM 454 Mag MPI Service Manual

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Inspecting

1. Inspect drive belt for the following:

Excessive wear

NOTE: Minor, transverse cracks (across the belt width) may be acceptable. Longitudinal

cracks (in direction of belt length) that join transverse cracks are NOT acceptable.

Glazed surfaces

1. Remove drive belt as follows:

a. Loosen 5/8 in. locking nut on adjustment stud.

b. Turn adjustment stud and loosen belt. Remove belt.

2. Install drive belt on pulleys and adjust tension as follows:

a. 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 dis-

tance between two (2) pulleys. Proper tension is 1/4 in. (6 mm) deflection with moderate

thumb pressure.

b. Use 5/16 in. socket and tighten adjusting stud until the correct deflection of the belt

c. While holding adjustment stud at the correct belt tension, tighten 5/8 in. locking nut.

d. Run engine for a short period of time and recheck belt adjustment.

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is obtained at location specified above.

5/8 in. Locking Nut

5/16 in Adjusting Stud

SERVICE MANUAL NUMBER 23

90-861326--1 MARCH 1999

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