Cummins/Onan — Valve Clearance Adjustment
Adjustments · Cylinder Head / Valves
From a Cummins/Onan service manual covering: P4500, P5000E, P5000e. Check it applies to your exact model before use.
Applies to: Cummins/Onan P4500
Before you start
- Valve clearance inspection and adjustment must be performed with the engine cold.
Procedure
- Remove the valve cover and set the piston at top dead center of the compression stroke.
- Insert a feeler gauge between the rocker arm and valve to measure valve clearance.
- If adjustment is necessary, hold the rocker arm pivot and loosen the pivot lock nut.
- Turn the rocker arm pivot to obtain the specified clearance.
- Retighten the lock nut while holding the rocker arm pivot.
- Recheck valve clearance after tightening the lock nut.
Tools required
- Feeler gauge Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Intake valve clearance 0.10 ±0.02 mm (0.004 ±0.001 in) cold
- Exhaust valve clearance 0.15 ±0.02 mm (0.006 ±0.001 in) cold
Full service-parts list: Cummins/Onan P4500 →
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.