Cummins/Onan — Starting Motor Removal and Disassembly
Repair & overhaul
From a Cummins/Onan service manual covering: 10.0JC, 12.5JC, 15.0JC, 4.0JB, 5.0JB, 6.0JB, 6.1JB, 7.5JB, 7.6JB. Check it applies to your exact model before use.
Applies to: Cummins/Onan 10.0JC, Cummins/Onan 12.5JC, Cummins/Onan 15.0JC, Cummins/Onan 5.0JB, Cummins/Onan 6.0JB, Cummins/Onan JB engine, Cummins/Onan JC engine
Before you start
- Do not attempt to disassemble the clutch assembly.
Procedure
- Remove electrical connections at the shifting solenoid; remove engine front air housing and flywheel.
- Remove nut holding starter rear mounting bracket; remove three capscrews at mounting flange and pull motor off, keeping any shims.
- Remove link pin holding shift lever to solenoid plunger and remove shift lever pivot pin.
- Remove thru bolts from commutator end; pull off end cover, lift brushes, and lift armature and clutch out of frame.
- To remove over-running clutch, drive retainer away from lockring, remove lockring and pull assembly off.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Armature end play .005 to .030 in.
- Pinion clearance .09 in. plus or minus .02 in.
Full service-parts list: Cummins/Onan 10.0JC →, Cummins/Onan 12.5JC →, Cummins/Onan 15.0JC →, Cummins/Onan 5.0JB →, Cummins/Onan 6.0JB →
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.