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Home›Repair guides›Spark Plug Inspection and Replacement

Onan — Spark Plug Inspection and Replacement

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

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Before you start

  • Engine must be cool before servicing spark plugs

Procedure

  1. Stop engine and allow to cool.
  2. Remove spark plug wire by grasping the boot and twisting gently.
  3. Use spark plug socket and extension to remove spark plug.
  4. Inspect spark plug electrode gap and condition.
  5. Clean or replace spark plug as needed.
  6. Install new or cleaned spark plug and torque to specification.
  7. Reinstall spark plug wire onto plug boot until firmly seated.

Tools required

  • Spark plug socket
  • Extension
  • Spark plug gauge

Specs & torque values

  • Spark plug gap specification: 0.028-0.032 inch

Source: manual:HDKAG Service Manual.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.