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Home›Repair guides›Adjustable Split Pulley Water Pump Belt Adjustment

Cummins/Onan — Adjustable Split Pulley Water Pump Belt Adjustment

A Cummins/Onan service procedure — check it applies to your exact model before use.

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Before you start

  • Clean capscrew threads thoroughly to avoid capscrew breakage during reassembly

Procedure

  1. Remove capscrews joining the sheaves of the pulley
  2. Clean capscrew threads and holes in sheaves thoroughly
  3. Bar the engine over to roll the belt outward on the pulley as the outer half is turned in
  4. Adjust belt tension to proper level
  5. Turn outer sheave to align capscrew holes
  6. Start capscrews and tighten alternately and evenly
  7. Bar engine over one or two revolutions to seat belt
  8. Recheck belt tension

Tools required

  • Socket wrench set
  • Engine barring tool

Specs & torque values

  • 5/16-18 capscrew torque: 10 to 12 ft-lbs
  • 3/8-16 capscrew torque: 17 to 19 ft-lbs

Source: manual:CUMMMINS_OPERATIONS_MAINTENANCE_1978.pdf. Figures and steps are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.