Cummins/Onan — Exhaust Water Separator Backflow Test
Testing & diagnosis
From a Cummins/Onan service manual — check it applies to your exact model before use.
Applies to: Cummins/Onan MDKAV, Cummins/Onan MDKAW, Cummins/Onan MDKAZ, Cummins/Onan MDKB, Kubota D1105 engine, Kubota V1305 engine, Kubota V1505 engine, Kubota V1903B engine, Kubota V2203B engine, Kubota V2803B engine
Before you start
- Backflow can cause major engine damage if the cylinders become flooded.
Procedure
- Conduct during sea trials together with the RAW WATER PICKUP TEST.
- Close the drain hose sea cock and disconnect the hose from the water separator.
- Open the sea cock while keeping the hose raised to its fitting on the water separator.
- Verify there is no backflow while operating the boat throughout its speed range; if there is, relocate the through-hull fitting.
Full service-parts list: Cummins/Onan MDKAV →, Cummins/Onan MDKAW →, Cummins/Onan MDKAZ →, Cummins/Onan MDKB →, Kubota D1105 engine →, Kubota V1305 engine →, Kubota V1903B engine →
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.