2018 Peterbilt 389 Coolant Capacity & Type

The 2018 Peterbilt 389 has a total cooling system capacity that typically ranges from 12 to 14 gallons (45.4 to 53 liters), depending on the specific engine and sleeper configuration.

Quick Answer

• Total Cooling System Capacity: 12–14 gallons (45.4–53 L) for engine and radiator, varies by configuration.
• OEM Coolant Specification: Red or Red/Orange Extended Life Coolant (ELC) meeting TMC RP-329 or Cummins CES 14603 specifications. This is a Nitrited Organic Additive Technology (NOAT) coolant.
• Mix Ratio: 50/50 mix of coolant concentrate and distilled water.

Capacity by Engine Option

The 2018 Peterbilt 389 was available with several engine options, primarily from PACCAR and Cummins. The total system capacity can vary slightly based on the engine, radiator size, and the presence of a sleeper cab with its own heater core.

Note: Always confirm the exact capacity for your specific VIN with a Peterbilt dealer or by referencing your owner's manual.

Flush Interval

• Normal Service: The recommended flush interval for Peterbilt ELC is typically 600,000 miles, 12,000 hours, or 6 years, whichever comes first.
• Severe Duty: For vehicles under severe duty, it is recommended to test the coolant annually and adjust the additive package as needed, with a complete flush closer to the 4-year/400,000-mile mark.

How to Refill & Bleed

Refilling a heavy-duty diesel engine requires care to avoid airlocks, which can cause overheating.

1. Ensure the engine is completely cool.
2. Open the radiator petcock (drain valve) on the bottom of the radiator and drain the old coolant into a large catch pan.
3. Close the petcock after draining.
4. Slowly fill the system through the expansion tank (surge tank) with a 50/50 mix of ELC and distilled water.
5. Leave the expansion tank cap off, start the engine, and turn the cabin heater to its highest setting.
6. Allow the engine to idle and reach operating temperature. You will see the coolant level drop as the thermostat opens and circulates coolant.
7. Continue to add coolant to the "MAX COLD" line on the expansion tank as the air bleeds out.
8. Once the engine is at full temperature and the coolant level is stable, replace the expansion tank cap.

Common Cooling System Issues

The Peterbilt 389 is a robust truck, but like any heavy-duty vehicle, it can experience cooling system issues. Common problems include:

• Radiator Leaks: Due to the large surface area and constant exposure to road debris, the radiator can develop leaks over time.
• EGR Cooler Failure: A failing EGR cooler can leak coolant into the exhaust system, often presenting as white smoke and gradual coolant loss.
• Water Pump Failure: The water pump is a wear item. Signs of failure include coolant leaking from the pump's weep hole or a grinding noise from the front of the engine.
• Hose Deterioration: Radiator and heater hoses can become brittle and crack over time, leading to leaks. Regular inspection is key.

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