2016 Peterbilt 579 Coolant Capacity & Type

The 2016 Peterbilt 579 holds approximately 13 to 15 gallons (49.2 to 56.8 liters) of coolant, depending on the engine and sleeper configuration.

Quick Answer

• Total Cooling System Capacity: 13–15 gallons (49.2–56.8 liters)
• OEM Coolant Specification: Red or Pink Extended Life Coolant (ELC), Nitrite-Free Organic Acid Technology (OAT). Look for coolants meeting TMC RP-329 or Cummins CES 14603 specifications.
• Mix Ratio: 50/50 mix of coolant concentrate and distilled water. Pre-mixed 50/50 solutions are recommended for convenience and accuracy.

Capacity by Engine Option

The 2016 Peterbilt 579 was primarily offered with two engine choices from PACCAR and Cummins, each having slight variations in cooling system capacity.

Note: Capacities can vary based on factors like sleeper size, auxiliary heaters (APUs), and specific radiator configurations. Always start with the lower estimated amount and add as needed.

Flush Interval

For heavy-duty diesel engines like those in the Peterbilt 579, following the correct flush interval is critical to prevent corrosion, liner pitting, and deposit formation.

• Normal Service: The factory-fill ELC in a 2016 Peterbilt 579 is designed for long life. The initial flush is typically recommended at 600,000 to 750,000 miles (or 12,000-15,000 operating hours).
• Severe Duty: If the vehicle is operated in harsh conditions, such as heavy-haul, frequent idling, or extreme temperatures, consider reducing the interval to 450,000-500,000 miles.
• Coolant Extenders: Some ELCs allow for an "extender" to be added at around 300,000-400,000 miles to replenish additives and further prolong the coolant's life before a full flush is required. Consult your coolant manufacturer's guidelines.

How to Refill & Bleed

Properly refilling and bleeding the air from a large diesel engine's cooling system is crucial to prevent overheating and airlocks.

1. Drain Old Coolant: Ensure the old coolant is completely drained from the radiator (via the petcock at the bottom) and the engine block drains.
2. Initial Fill: Using a 50/50 pre-mix or a properly mixed concentrate/distilled water solution, begin filling the system through the expansion tank (surge tank). Fill slowly to minimize air entrapment.
3. Venting Air: Unlike many passenger cars, these trucks often have vent plugs or petcocks located at high points in the cooling system, such as on the thermostat housing or top radiator hose. Open these vents during filling until a steady stream of coolant emerges, then close them.
4. Run and Bleed: Start the engine with the heater set to high. Let the engine idle and come up to operating temperature. This allows the thermostat to open and circulate coolant. You will notice the coolant level in the expansion tank drop; continue to top it off to the "COLD FULL" line as air purges.
5. Vacuum-Fill Note: Many professional shops use a vacuum-fill tool (like an Airlift) on these systems. This tool pulls the entire cooling system into a deep vacuum, removing all air before coolant is drawn in. This is the most effective method for preventing airlocks in complex systems.
6. Final Check: After the engine has fully warmed up and cooled down, re-check the coolant level in the surge tank and top off as necessary.

Common Cooling System Issues

The PACCAR MX-13 and Cummins ISX15 engines are robust, but certain cooling system problems can arise over their service life.

• EGR Cooler Failure: The Exhaust Gas Recirculation (EGR) cooler is a common point of failure. When it fails internally, coolant can leak into the exhaust or exhaust gases can contaminate the coolant, leading to overheating and pressure issues.
• Radiator and Hose Leaks: Given the high mileage and constant vibration, radiator tanks (often plastic sides crimped to an aluminum core) can develop cracks. Hose connections, especially at the radiator, turbo, and engine block, are also common leak points.
• Water Pump Failure: While generally durable, the water pump can fail over time. Symptoms include a coolant leak from the weep hole on the pump housing, a "grinding" noise, or an overheating condition.
• Sensor Failures: Faulty coolant level or temperature sensors can provide inaccurate readings to the dashboard and engine control module (ECM), potentially triggering warning lights or causing improper engine fan operation.

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