Cummins/Onan 3.6MKY / 4MKY — Brush Replacement
Maintenance · Brush block
For the Cummins/Onan 3.6MKY / 4MKY, from the Cummins/Onan service manual.
Applies to: Cummins/Onan 3.6MKY, Cummins/Onan 4MKY
Before you start
- Always replace the brush springs when installing new brushes
Procedure
- Remove the fan (Steps 1 through 9).
- Inspect brushes and brush block for burn marks or damage; check brush wear with modified wire (minimum brush length 0.375 inches [9.5 mm]).
- Remove brush block mounting screws and lift out the brush block.
- Remove brushes and springs from holder and replace with new parts.
- Push each brush into holder and insert a stiff wire through small hole in base of holder.
- Install brush block in endbell but do not tighten mounting screws.
- Remove wire holding brushes off slip rings; center brushes on slip rings and tighten screws.
- Reassemble the generator.
Tools required
- Modified wire wear gauge Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Minimum brush length 0.375 inches (9.5 mm)
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.