Cummins/Onan 205AJ — Tappet adjustment
Adjustments · valve train
For the Cummins/Onan 205AJ, from the Cummins/Onan operator's manual.
Applies to: Cummins/Onan AJ series
Procedure
- Remove valve compartment cover and blower housing.
- Crank engine by hand until intake valve opens and closes.
- Continue turning flywheel slowly until flywheel mark aligns with TC mark on gear cover.
- Check tappet clearance per Table of Clearances.
- Use 7/16 in wrench for adjusting screw and 9/16 in wrench for tappet.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- .010 in - .012 in for intake and exhaust valves
Full service-parts list: Cummins/Onan AJ series →
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.