Replacing Belt And/Or Adjusting Tension - MerCruiser 4.3 TKS User Manual

Section 5 - Maintenance
• 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 a 8 mm (5/16 in.) socket and tighten adjusting the stud to adjust the belt deflection.
6. Using one of the 2 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.).
b. Attach the Kent Moore Belt Tension Gauge to the belt. The gauge has different ranges for new and used belts.
b
7. While holding the adjustment stud at the correct belt tension, tighten the 16 mm (5/8 in.) locking nut.
a
8. Operate the engine for a short period of time and recheck the belt adjustment.
Page 70
mc75130-1
a
a - 16 mm (5/8 in.) locking nut
b - 8 mm (5/8 in.) adjusting stud
b
6119
a - Kent Moore Tension Gauge
b - Serpentine belt
14980
90-8M0053372 NOVEMBER 2010
eng