Serpentine Drive Belt; Checking; Replacing Belt And/Or Adjusting Tension - Mercury MerCruiser Tow Sport 5.7 LHS Manual

Serpentine Drive Belt

Inspecting the belts with the engine running may cause serious injury or death. Turn off the engine and remove the ignition
key before adjusting tension or inspecting belts.
a
e

Checking

Inspect the drive belt for proper tension and for the following:
• Excessive wear
• Cracks
NOTE: Minor transverse cracks (across the belt width) may be acceptable. Longitudinal cracks (in the direction of belt
length) that join transverse cracks are NOT acceptable.
• Fraying
• Glazed surfaces
• Proper tension ‑ 13 mm (1/2 in.) deflection, with moderate thumb pressure, on the belt at the location that has the longest
distance between two pulleys.

Replacing Belt and/or Adjusting Tension

IMPORTANT: If a belt is to be reused, it should be installed in the same direction of rotation as before.
NOTE: Belt deflection is to be measured on the belt at the location that has the longest distance between two pulleys.
1. Loosen the 16 mm (5/8 in.) locking nut on the adjustment stud.
2. Turn the adjustment stud and loosen the belt.
3. If a new serpentine drive belt is required, remove the old belt and install a new belt onto the pulleys.
4. Put a wrench on the adjustment stud 16 mm (5/8 in.) locking nut.
5. Use an 8 mm (5/16 in.) socket and tighten the adjusting stud to adjust the belt deflection.
6. Using one of the two methods following, check for correct deflection.
a. Push down with moderate thumb pressure on the longest stretch of belt. Proper deflection is 13 mm (1/2 in.).
90-8M0086943 DECEMBER 2014
eng
a - Idler pulley
b - Circulating pump pulley
c - Crankshaft pulley
d - Alternator pulley
e - Seawater pump pulley
b
d
c
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WARNING
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mc75130-1
Section 5 - Maintenance
Page 51