Cummins/Onan NH-MS/1 / NH-S/1 — Tappet (Valve Clearance) Adjustment
Adjustments · Valve tappets
For the Cummins/Onan NH-MS/1 / NH-S/1, from the Cummins/Onan service manual.
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Procedure
- Remove the valve covers.
- Crank the engine slowly by hand until the left hand intake valve, facing the flywheel, opens and closes.
- Continue about 1/4 turn until the flywheel mark and the TC mark on the gear cover are in line.
- Check that the gauge just passes between the valve stem and valve tappet.
- Turn the self-locking adjusting screw to obtain the right clearance.
- Crank the engine one complete revolution, line up the marks, then adjust the right hand cylinder valves.
Tools required
- Standard automotive type wrench
- Thickness gauge Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Intake 0.003 in
- Exhaust 0.010 in
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.