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Home›Repair guides›Cummins/Onan›Valve clearance adjustment MJC/RJC

Cummins/Onan — Valve clearance adjustment MJC/RJC

Adjustments

From a Cummins/Onan service manual — check it applies to your exact model before use.

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Procedure

  1. Adjust valve clearance in firing order 1-2-4-3 sequence.
  2. Set timing for number 1 cylinder and adjust its valve clearance.
  3. Turn flywheel 180 degrees clockwise for number 2 cylinder; adjust clearance.
  4. Turn flywheel 180 degrees clockwise for number 4 cylinder; adjust clearance.
  5. Turn flywheel 180 degrees clockwise for number 3 cylinder; adjust clearance.

Tools required

Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.

Specs & values

  • MJC/RJC intake 0.015 in (0.38 mm) cold
  • MJC/RJC exhaust 0.020 in (0.51 mm) cold

Source: Cummins/Onan service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.

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