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Cummins/Onan DJ30 — Adjust Valve Clearance

Adjustments · Cylinder head valves

For the Cummins/Onan DJ30, from the Cummins/Onan service manual.

Applies to: Onan (Onan Division of Studebaker Corporation, Minneapolis, Minnesota) Spec T, Cummins/Onan DJA engine

Before you start

  • Check valve clearance when the engine is at room temperature about 70 F

Procedure

  1. Turn the flywheel until the cylinder is on its compression stroke.
  2. Turn the flywheel clockwise an additional 10 to 45 degrees.
  3. Loosen the rocker arm locknut to increase clearance, tighten to reduce clearance.
  4. Check clearance with a feeler gauge between rocker arm and valve.
  5. Set clearance to 0.011 inch intake and 0.008 inch exhaust.

Tools required

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

Specs & values

  • Intake 0.011 inch
  • Exhaust 0.008 inch

Full service-parts list: Onan (Onan Division of Studebaker Corporation, Minneapolis, Minnesota) Spec T →

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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