Cummins/Onan 6.0 NH-1R/9500 / 6KW Power Drawer — Tappet Adjustment
Adjustments · Valve tappets
For the Cummins/Onan 6.0 NH-1R/9500 / 6KW Power Drawer, from the Cummins/Onan service manual.
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Procedure
- Remove exhaust and intake manifold and valve box cover.
- Remove spark plugs to ease turning engine by hand.
- Turn engine by hand until left intake valve opens and closes; align TC marks.
- Intake valve: .003 inch thickness gauge should just pass between valve stem and tappet.
- Exhaust valve: .012 inch thickness gauge should just pass.
- Use 7/16 inch open end wrench to turn adjusting screw; 9/16 inch wrench to hold tappet.
- For right cylinder, turn engine one complete revolution and align marks; repeat procedure.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Intake .003 inch
- Exhaust .012 inch
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.