Cummins/Onan — Timing Gears Replacement
Repair & overhaul
From a Cummins/Onan service manual — check it applies to your exact model before use.
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Procedure
- If replacing crankshaft gear or camshaft gear, install both gears new.
- Remove crankshaft gear: remove snap ring, attach gear pulling ring (Onan Tool No. 420A248) with two #10-32 screws.
- Tighten screws alternately; attach gear puller to puller ring and remove gear.
- Camshaft gear is pressed on and keyed to camshaft.
- Remove camshaft and gear as assembly after removing crankshaft gear lock ring and washer.
- Before removing camshaft and gear, remove cylinder head, valve assemblies, fuel pump, and tappets.
- Remove governor cup assembly from gear.
- Press camshaft out of gear using hollow tool or pipe fitting over camshaft center pin; do not press on center pin.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
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.