Cummins/Onan — Valve Lash Adjustment

Adjustments · Engine valves

From a Cummins/Onan service manual — check it applies to your exact model before use.

Applies to: Cummins/Onan HGJAA, Cummins/Onan HGJAB, Cummins/Onan HGJAD, Cummins/Onan HGJAE

Procedure

1. Torque the adjustment lock nut to 6.5 lb-ft (8.5 Nm) while preventing the holding nut from turning, recheck lash.
2. Remove the spark plugs so engine is easier to turn over.
3. Use a socket wrench on the alternator pulley nut to turn the engine clockwise.
4. Remove the snap-in cover in the access hole in the drip pan.
5. Remove the valve covers, with rags to catch spilled oil.
6. Turn engine until Cylinder No. 2 intake valve (top) is at maximum lift.
7. Adjust Cylinder No. 1 intake valve lash.
8. Turn engine until Cylinder No. 2 exhaust valve (bottom) is at maximum lift.
9. Adjust Cylinder No. 1 exhaust valve lash.
10. Turn engine until Cylinder No. 1 intake valve is at maximum lift; adjust Cylinder No. 2 intake valve lash.
11. Turn engine until Cylinder No. 1 exhaust valve is at maximum lift; adjust Cylinder No. 2 exhaust valve lash.
12. Secure valve covers with new gaskets; torque cover screws to 5.5 lb-ft (8 Nm).
13. Replace the spark plugs and pulley nut cover.

Full service-parts list: Cummins/Onan HGJAA →, Cummins/Onan HGJAB →, Cummins/Onan HGJAD →

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.

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