Cummins/Onan 3.6MKY / 4MKY — Crankcase Breather Service
Maintenance · Crankcase ventilation system
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
- Most parts cleaning solvents are flammable; follow manufacturer recommendations.
Procedure
- Remove the breather tube from the valve cover.
- Remove the head cover and breather assembly.
- Inspect the reed valve; it must be flat with no creases; replace if defective.
- Clean a dirty breather in parts cleaning solvent.
- Check the breather tube and air passages for clogging and clean as required.
Tools required
- Parts cleaning solvent Amazon
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.