Cummins/Onan 4MCCK / 605MCCK — Thermo-Magnetic Choke Adjustment
Adjustments
For the Cummins/Onan 4MCCK / 605MCCK, from the Cummins/Onan service manual.
Applies to: Cummins/Onan 605MCCK, Cummins/Onan MCCK, Cummins/Onan MCCK engine
Procedure
- Do not attempt adjustments until the engine has been shut down for at least one hour; adjust with the bimetal at ambient temperature.
- Remove the flame arrester and adapter to expose the carburetor throat.
- Loosen the screw which secures the choke body assembly.
- Use a drill or the shank of a drill bit to measure the choke opening.
- For a richer mixture turn the choke body clockwise; to lean it turn counterclockwise.
- Tighten the screw that secures the choke body.
Tools required
- drill or drill bit shank Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Choke heater resistance should be about 30.6 to 37.4 ohms for a 12-volt Amazon eBay $11.99 FridayParts $65.01 system
- Solenoid coil resistance should be 2.09 to 2.31 ohms in a 12-volt Amazon eBay $11.99 FridayParts $65.01 system
Full service-parts list: Cummins/Onan 605MCCK →, Cummins/Onan MCCK →
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.