Cummins/Onan Onan P4500i Inverter / P4500 — Valve Clearance
Adjustments · Valve train
For the Cummins/Onan Onan P4500i Inverter / P4500, from the Cummins/Onan operator's manual.
Applies to: Cummins/Onan P4500
Before you start
- Checking and adjusting valve clearance must be done when the engine is cold.
Procedure
- Remove the rocker arm cover and carefully remove the gasket; replace if torn or damaged.
- Remove the spark plug so the engine can be rotated more easily.
- Rotate the engine to top dead center (TDC) by pulling the recoil handle slowly.
- Verify both rocker arms are loose at TDC on the compression stroke; if not, rotate the engine 360°.
- Insert a feeler gauge between the rocker arm and valve stem to measure valve clearance.
- If adjustment is needed, hold the rocker arm pivot and loosen the pivot adjusting nut.
- Turn the rocker arm pivot to obtain the specified clearance; re-tighten the nut to the specified torque.
- Perform the procedure for the other valve.
- Install the gasket, rocker arm cover, and spark plug.
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 clearance: 0.0031 – 0.0047 in (0.08 – 0.12 mm)
- Exhaust clearance: 0.0051 – 0.0067 in (0.13 – 0.17 mm)
- Torque: 8-12 N•m
- Torque: 106 inch-pound (12 N•m)
Full service-parts list: Cummins/Onan P4500 →
Source: Cummins/Onan operator's 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.