Cummins/Onan — Cleaning and Draining the Heat Exchanger
Maintenance
From a Cummins/Onan service manual — check it applies to your exact model before use.
Applies to: Cummins/Onan MDKB, Cummins/Onan MDKBH
Before you start
- Disconnect the negative battery cable to prevent accidental starting.
Procedure
- Remove the end enclosure panel or the raw water pump for access.
- Have towels and containers ready to prevent spilling raw water on electrical components.
- Remove the drain plug or cleanout cover and clean and flush the tubes.
- Do not use metal rods to clean the tubes (soft copper alloy).
- Use thread sealant on the drain plug and a new cleanout cover gasket if the old one is damaged.
- Reassemble all parts that were disassembled for access.
Specs & values
- Heat exchanger mounting bolts torque 19 lb-ft (26 N-m)
Full service-parts list: Cummins/Onan MDKB →, Cummins/Onan MDKBH →
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.