Cummins/Onan DJ30 — Adjust Decompression Release
Adjustments · Decompression mechanism
For the Cummins/Onan DJ30, from the Cummins/Onan service manual.
Applies to: Onan (Onan Division of Studebaker Corporation, Minneapolis, Minnesota) Spec T, Cummins/Onan DJA engine
Before you start
- If the screw is tightened more than one turn, the exhaust valve could hit the piston
Procedure
- Set valves for correct clearance first.
- Leave flywheel at 10 to 45 degrees ATC with piston on power stroke.
- Set arm in decompression position; turn setscrew until it just touches exhaust rocker arm.
- Turn the screw exactly one revolution clockwise.
- Hold setscrew and tighten lock nut 1/4 to 1/2 turn past finger tightness.
Tools required
- Feeler gauge Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Full service-parts list: Onan (Onan Division of Studebaker Corporation, Minneapolis, Minnesota) Spec T →
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.