2017 Peterbilt 579 Coolant Capacity & Type

The 2017 Peterbilt 579 holds approximately 60-70 quarts (56.8-66.2 Liters) of coolant, depending on the engine and specific cooling system configuration.

Quick Answer

• Total Cooling System Capacity: 60-70 quarts (56.8-66.2 Liters)
• OEM Coolant Spec: Extended Life Coolant (ELC) – typically a red/purple, Organic Acid Technology (OAT) or Hybrid Organic Acid Technology (HOAT) type, designed to meet Cummins CES 14603 or Detroit Diesel DFS93K217 specifications. Always verify with your owner's manual.
• Mix Ratio: 50/50 prediluted or concentrate mixed with distilled water.

Capacity by Engine Option

The Peterbilt 579 was available with several engine options, and each may have slight variations in cooling system capacity. The capacities listed below are approximate and include the expansion tank.

Flush Interval

Maintaining your coolant is crucial for the longevity of your engine. Adhere to the following guidelines for coolant flush intervals:

• Normal Duty: Typically 300,000 miles or 3 years, whichever comes first, for Extended Life Coolants (ELC).
• Severe Duty: If your truck operates under severe conditions (e.g., frequent heavy loads, extreme temperatures, dusty environments), consider flushing and refilling every 150,000 miles or 1.5 years.

Always consult your Peterbilt owner's manual or engine manufacturer's guidelines for the most accurate and up-to-date service intervals.

How to Refill & Bleed

Properly refilling and bleeding the cooling system in a Peterbilt 579 is essential to prevent air pockets, which can cause overheating. While professional assistance is recommended, here are general steps:

1. Drain: With the engine cool, carefully drain the old coolant from the radiator and engine block drain plugs.
2. Flush (Optional but Recommended): Flush the system with distilled water until clear, then drain completely. Avoid using tap water to prevent mineral deposits.
3. Refill: Close all drain plugs. Begin refilling the system slowly with the specified ELC coolant (50/50 mix) through the coolant reservoir.
4. Bleed: Start the engine with the heater on full blast and the coolant reservoir cap off. Allow the engine to reach operating temperature. Air bubbles will escape through the reservoir. You may need to gently squeeze radiator hoses to help dislodge air. Continue to top off the reservoir as the coolant level drops.
5. Check for Bleed Screws/Valves: Some Peterbilt 579 models, or their engines, may have specific air bleed screws or valves located on the thermostat housing, heater core lines, or other high points in the system. Consult your service manual for their exact location and operation.
6. Vacuum Fill (Recommended): For best results and to ensure all air is removed, a vacuum-fill tool is highly recommended for these complex cooling systems. This method pulls a vacuum on the system before refilling, drawing in coolant and virtually eliminating air pockets.
7. Final Check: Once the engine is cool, recheck the coolant level and top off if necessary. Monitor the coolant level and engine temperature closely during the next few driving cycles.

Common Cooling System Issues for This Generation

Owners of 2017 Peterbilt 579 trucks (and similar heavy-duty trucks of this era) may encounter the following cooling system issues:

• Radiator Leaks: Due to constant vibration and demanding conditions, radiator tanks or core seams can develop leaks over time.
• Coolant Hose Failure: Hoses can degrade, swell, or crack, leading to leaks. Inspect all hoses for signs of wear regularly.
• Water Pump Failure: The water pump is a critical component; signs of failure include leaks from the weep hole, bearing noise, or overheating.
• Thermostat Malfunctions: A stuck-open thermostat can lead to the engine running too cool, while a stuck-closed thermostat will cause rapid overheating.
• EGR Cooler Issues: For engines equipped with Exhaust Gas Recirculation (EGR) systems, the EGR cooler can be a source of coolant leaks, especially internal leaks that can mix exhaust gases with the coolant.
• Coolant System Contamination: Using the wrong type of coolant or mixing incompatible coolants can lead to gelling, corrosion, and system blockages.
• Fan Clutch Problems: A malfunctioning fan clutch can prevent the cooling fan from engaging properly, leading to overheating, especially at idle or low speeds.

Regular maintenance and using the correct coolant type are paramount to preventing these issues.

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