Cummins/Onan — Coolant System Filling
Maintenance · Cooling system
From a Cummins/Onan owner's manual covering: 4B3.9, 4BT 3.9, 4BTA 3.9, 6B5.9, 6BT 5.9, 6BTA5.9, B5.9-160, B5.9-175, B5.9-190, B5.9-210, B5.9-230. Check it applies to your exact model before use.
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Before you start
- Do not remove pressure cap until coolant temperature below 50°C [120°F]. Never use water alone.
Procedure
- System has maximum fill rate of 14 liters per minute [3.5 U.S. gallons per minute]. Do not exceed.
- Use mixture of 50% water and 50% ethylene glycol antifreeze.
- Fill slowly; vent air from engine and aftercooler. Wait 2 to 3 minutes, then add mixture to top.
- Install pressure cap. Operate engine to 80°C [180°F] and check for leaks.
- Check coolant level again.
Specs & values
- Maximum fill rate 14 L/min [3.5 U.S. gal/min]
- 50% water / 50% ethylene glycol
- Coolant capacity: 4B3.9/4BT3.9 7.0 L [7.4 qt]; 4BTA3 SinoCMP $149.00.9 7.9 L [8.4 qt]; 6B5.9/6BT5.9 9.0 L [9.5 qt]; 6BTA5 SinoCMP $329.00.9 9.9 L [10.5 qt]
Source: Cummins/Onan owner's 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.