Cummins/Onan 205AJ — Valve service
Repair & overhaul · cylinder head
For the Cummins/Onan 205AJ, from the Cummins/Onan operator's manual.
Applies to: Cummins/Onan AJ series
Before you start
- Do not pry cylinder head; avoid breaking cooling fins.
Procedure
- Remove aluminum cylinder head; do not pry; rap edge with soft-faced hammer.
- Use valve spring lifter to remove split valve spring locks.
- Clean carbon deposits from cylinder head, piston top, valves, guides.
- Replace burned, warped, or worn valves.
- Grind valve faces to 44° and seats with 45° stone; seat band width 2/64 to 3/64 in.
- Remove all grinding compound; check each valve for tight seat.
- Lightly oil valve stems and reassemble; adjust valve clearance.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Valve face angle 44°
- Valve seat angle 45°
- Seat band width 2/64 in - 3/64 in
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.