Cummins/Onan — Filling the Coolant System
Maintenance
From a Cummins/Onan service manual covering: ES2075s, FS1870s, M11979s, M1976s, M1977s, M1978s. Check it applies to your exact model before use.
Applies to: Kubota 2482B engine
Before you start
- Disconnect the 3-pin connector inside the power unit any time the top cover is removed.
- Accidentally starting the power unit while working on it can cause severe personal injury or death.
Procedure
- Remove the power unit top cover and disconnect the 3-pin connector inside the power unit.
- Close all coolant drain valves and hose shutoff valves if coolant was drained.
- Fill the main truck engine coolant system per the truck engine Operator's manual.
- Check all hose fittings are tightly secured with hose clamps.
- Open the supply valve and keep the return valve closed if shutoff valves are used.
- Start the main truck engine and run it at a minimum speed of 1000 rpm.
- Bleed the power unit engine by loosening the hose clamp at the thermostat housing just enough to bleed.
- Remove the cap from the access valve on top of the power unit radiator and depress the valve pin to bleed air; reinstall the cap.
- Reconnect the 3-pin connector and install the power unit top cover.
- Open the main engine coolant return valve and add coolant to the main coolant system.
- Cycle the Heat/Off/AC switch between Heat and Off until the heater blows warm air.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Main truck engine minimum speed 1000 rpm
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.