Cummins/Onan — Decompression Release Adjustment
Adjustments
From a Cummins/Onan service manual covering: 205D3A, 3DJA, 3DJA-1E2236, 3DJA-3E2236. Check it applies to your exact model before use.
Applies to: Cummins/Onan DJA engine
Before you start
- If screw is tightened more than one turn, exhaust valve could hit piston
Procedure
- Valves must be set for correct clearance first.
- With piston 10 to 45 degrees past TDC on power stroke, hold arm in decompression position.
- Turn set screw so it just touches exhaust rocker arm.
- Turn screw exactly one revolution clockwise; lock with nut.
- Release mechanism; check clearance; back off set screw if no clearance.
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.