Cummins/Onan — Clean Cooling System - Chemical Cleaning and Pressure Flushing
Maintenance
From a Cummins/Onan service manual covering: V12 Series, V6-140, V6-200, V6-VAL, V6-VIM, V8-185, V8-265, V8-350, V8-VALE, V8-VINE, VT12, VT8-430. Check it applies to your exact model before use.
Applies to: Cummins/Onan V12 Series
Before you start
- Apply air pressure gradually to avoid damage to the core.
Procedure
- Use a good cooling system cleaner such as sodium bisulphate or oxalic acid followed by neutralizer and flushing.
- Open upper and lower hose connections; screw radiator cap on tight.
- Remove thermostats from housing and flush block with water.
- Attach flushing gun nozzle to lower hose connection; let water run until radiator full.
- Apply air pressure gradually; shut off air and allow radiator to refill; repeat until water is clean.
- Partially restrict lower opening until block fills; apply air pressure; repeat until stream is clean.
Tools required
- Flushing gun Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Full service-parts list: Cummins/Onan V12 Series →
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.