2024 Kenworth T680 Coolant Capacity & Type

The 2024 Kenworth T680 typically holds between 70 and 80 quarts (66 to 76 liters) of coolant, depending on the engine and specific configuration.

Quick Answer

• Total Cooling System Capacity: 70-80 quarts (66-76 liters)
• OEM Coolant Spec: PACCAR Engine Coolant (EC-1, Silicate-Free, Nitrite-Free, Phosphate-Free, OAT - Organic Acid Technology)
• Mix Ratio: 50/50 ready-to-use or concentrate mixed with distilled water

Capacity by Engine Option

Note: These capacities are approximations and can vary slightly based on radiator size, heater core options, and other vehicle-specific configurations. Always refer to your owner's manual for the most accurate information.

Flush Interval

Maintaining your coolant is crucial for the longevity of your engine. For the 2024 Kenworth T680, the general guidelines are:

• Normal Duty: Replace coolant every 300,000 miles, 4,800 operating hours, or 3 years, whichever comes first.
• Severe Duty (e.g., heavy hauling, frequent idling, extreme temperatures): Consider reducing the flush interval to 200,000 miles, 3,200 operating hours, or 2 years.

Always use PACCAR EC-1 compliant coolant or an equivalent that meets the OAT, silicate-free, nitrite-free, and phosphate-free specifications. Using incompatible coolants can lead to premature wear and damage to cooling system components.

How to Refill & Bleed

Refilling and bleeding the cooling system on a heavy-duty truck like the Kenworth T680 requires careful attention to detail to ensure all air is removed.

1. Safety First: Ensure the engine is cool before beginning any cooling system work. Wear appropriate personal protective equipment.
2. Drain: Completely drain the old coolant from the radiator and engine block drain plugs. For a full flush, follow manufacturer recommendations for flushing agents.
3. Refill: Close all drain plugs. Slowly fill the system with the correct 50/50 coolant mixture through the surge tank or radiator fill neck. Fill until the coolant level is visible in the surge tank.
4. Idle and Bleed: Start the engine and let it run at a high idle (around 1000-1200 RPM, if safe and within manufacturer guidelines) with the heater on full hot (to open the heater core circuit). Monitor the coolant level in the surge tank and add as needed. Some T680 models, particularly those with PACCAR MX-13 engines, may have a dedicated air bleed valve on the thermostat housing or elsewhere on the engine. If present, open this valve during filling to help evacuate air.
5. Check for Leaks: While the engine is running and after it has reached operating temperature, carefully inspect all hoses, clamps, and connections for any signs of leaks.
6. Cool-Down and Recheck: Allow the engine to cool completely. Check the coolant level in the surge tank again and top off if necessary. The system may require several heat cycles and cool-downs to fully purge all air.
7. Vacuum Fill (Recommended for Professional Service): For optimal air evacuation and to prevent air pockets, a vacuum-fill tool is often recommended, especially in professional service environments. This method pulls a vacuum on the cooling system before filling, ensuring a complete and air-free fill.

Common Cooling System Issues

Owners of 2024 Kenworth T680s, like most modern heavy-duty trucks, can experience various cooling system issues if not properly maintained.

• Coolant Leaks: Due to the extensive network of hoses, clamps, and seals, leaks can develop over time. Pay attention to puddles under the truck or a steadily dropping coolant level.
• Thermostat Failure: A stuck-open thermostat can lead to the engine running too cool, reducing efficiency, while a stuck-closed thermostat can cause severe overheating.
• Radiator or Heater Core Clogging: Using incorrect coolant or neglecting flushes can lead to sediment buildup, restricting coolant flow and reducing cooling efficiency. External fins can also become clogged with debris.
• Water Pump Failure: The water pump is a critical component. Wear to its bearings or seal can lead to leaks or a complete loss of coolant circulation.
• EGR Cooler Issues: Diesel engines often have Exhaust Gas Recirculation (EGR) coolers that are part of the cooling system. Internal leaks in the EGR cooler can introduce coolant into the exhaust or combustion chambers, leading to white smoke or coolant loss.
• Degradation of Coolant: Over time, even proper coolants lose their protective additives. This can lead to corrosion, cavitation, and premature failure of cooling system components.

Regular inspections and adherence to the recommended maintenance schedule are key to preventing these issues and ensuring the reliable operation of your Kenworth T680.

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