Cummins/Onan NH-MS/1 / NH-S/1 — Oil Pressure Relief Valve Adjustment
Adjustments
For the Cummins/Onan NH-MS/1 / NH-S/1, from the Cummins/Onan service manual.
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Before you start
- Check the oil pressure gauge before making any other test; it may be defective.
Procedure
- Loosen the locknut on the slotted stud located near the breather tube.
- Turn the stud inward to increase oil pressure or outward to decrease it.
- Tighten the locknut securely after making the adjustment.
- The spring and plunger can be removed and cleaned.
Tools required
- Wrench Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Oil pressure 30 to 35 lbs when the engine is thoroughly warmed up
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.