Cummins/Onan 10W30 — Spark Plug Inspection and Regapping
Maintenance · Ignition system / spark plugs
For the Cummins/Onan 10W30, from the Cummins/Onan operator's manual.
Applies to: Cummins/Onan GGHE, Cummins/Onan GGHF, Cummins/Onan WSG-1068 engine
Before you start
- Carbon Fouled indicates overly rich mixture; Oil Fouled indicates high oil consumption; Burned indicates excessive engine temperature.
Procedure
- Remove the spark plugs and inspect for damaged or cracked insulators, worn electrodes, or excessive carbon deposits.
- Replace the spark plug if any of these conditions are noted.
- Clean those plugs that can be reused and regap to the amount specified in the Specifications section.
- Clean all dirt and grit away from the spark plug seats before installing.
- Lightly lubricate spark plug threads with high temp anti-seize compound (not required for standby power genset spark plugs).
Tools required
- spark plug gap gauge Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Spark plug gap 0.044 inch (1.1 mm)
Full service-parts list: Cummins/Onan GGHE →, Cummins/Onan GGHF →
Source: Cummins/Onan operator's 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.