2014 Kenworth T680 Coolant Capacity & Type

The 2014 Kenworth T680 typically holds between 60 to 75 quarts (56.8 to 71.0 liters) of coolant, depending on the specific engine and cooling system configuration.

Quick Answer

• Total Cooling System Capacity: 60-75 Quarts (56.8-71.0 Liters)
• OEM Coolant Spec: Predominantly uses an Extended Life Coolant (ELC) which is an Organic Acid Technology (OAT) or Hybrid Organic Acid Technology (HOAT) type. It is typically red, pink, or purple and meets TMC RP 329 or TMC RP 330 standards for heavy-duty applications. Always consult your owner's manual or engine manufacturer's specifications for the precise requirement.
• Mix Ratio: 50/50 Pre-mix or Concentrate mixed 50/50 with distilled water.

Capacity by Engine Option

The Kenworth T680 in 2014 was commonly equipped with Cummins ISX15 and PACCAR MX-13 engines. Coolant capacities can vary slightly based on radiator size, heater cores, and other accessories.

Flush Interval

Coolant flush intervals for heavy-duty trucks like the Kenworth T680 are significantly longer than passenger vehicles due to the use of ELC.

• Normal Duty: Typically, 600,000 miles, 12,000 hours, or 6 years, whichever comes first.
• Severe Duty (e.g., frequent idling, extreme temperatures, heavy loads): It's advisable to monitor coolant condition annually and consider a flush around 300,000-400,000 miles, 6,000-8,000 hours, or 3-4 years.

Regularly testing your coolant with test strips is crucial to determine if supplemental coolant additives (SCAs) are needed or if a flush is premature for severe duty cycles.

How to Refill & Bleed

Properly refilling and bleeding the cooling system on a Kenworth T680 is critical to prevent air pockets, which can lead to overheating and engine damage. This is a general guide; always refer to the specific service manual for your truck.

1. Drain: With the engine cool, open the petcock on the bottom of the radiator and any drain plugs on the engine block. Collect all old coolant in an appropriate container.
2. Flush (Optional but Recommended): After draining, you can run distilled water through the system until it runs clear to remove any remaining old coolant or sediment. If using a chemical flush, follow product instructions carefully.
3. Close Drains: Close all petcocks and drain plugs.
4. Fill Slowly: Begin filling the expansion tank (surge tank) with the recommended 50/50 coolant mixture. Fill slowly to allow air to escape.
5. Start Engine & Idle: Once full, start the engine and let it idle with the expansion tank cap off. Monitor the coolant level as the engine warms up and the thermostat opens. Add coolant as needed.
6. Run Heater: Turn the cabin heater to its highest setting to open the heater core circuit and allow air to bleed from that part of the system.
7. Check for Bleed Screws/Valves: Some heavy-duty engines may have bleed screws or valves on the thermostat housing or other high points in the system. Loosen these slightly until a steady stream of coolant (no air bubbles) emerges, then retighten.
8. Re-check Level & Drive Cycle: Once the engine is at operating temperature and no more air bubbles appear, top off the expansion tank to the "cold fill" line and replace the cap. Drive the truck through a few warm-up and cool-down cycles, then re-check the coolant level when the engine is cold and top off as necessary.
9. Vacuum Fill (Recommended for some systems): For some complex heavy-duty cooling systems, a vacuum-fill tool is highly recommended or even necessary to ensure all air is removed effectively.

Common Cooling System Issues for this Generation

Owners of 2014 Kenworth T680 trucks (and similar heavy-duty models from this era) may encounter several common cooling system issues:

• Radiator Leaks: Due to constant vibration, road debris, and pressure cycles, radiator leaks, especially at plastic end tanks, are common.
• Hose Failures: Coolant hoses can degrade over time, leading to cracks, leaks, or bursting. Inspect hoses for swelling or hardness.
• Water Pump Failure: The water pump is a wear item. Signs of failure include leaks from the weep hole, bearing noise, or overheating.
• Thermostat Issues: A stuck-open thermostat can lead to the engine running too cool, reducing efficiency, while a stuck-closed thermostat will cause rapid overheating.
• EGR Cooler Leaks: For trucks equipped with Exhaust Gas Recirculation (EGR) systems, the EGR cooler can be a common point of failure, leading to coolant loss or contamination.
• Coolant Contamination: Mixing incorrect coolant types or neglecting maintenance can lead to scale buildup, premature wear, and reduced cooling efficiency.
• Fan Clutch Malfunctions: The engine cooling fan is essential for maintaining temperatures, especially at low speeds or while idling. Fan clutch issues can lead to overheating.

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