2018 Kenworth W900 Coolant Capacity & Type

The 2018 Kenworth W900 typically holds between 70 to 80 quarts (66 to 76 liters) of coolant, depending on the specific engine and cooling system configuration.

Quick Answer

• Total Cooling System Capacity: 70–80 quarts (66–76 liters)
• OEM Coolant Spec: Extended Life Coolant (ELC), typically red or purple, meeting Cummins CES14603 or Detroit Diesel DFS93K217 specifications. This is an OAT (Organic Acid Technology) or HOAT (Hybrid Organic Acid Technology) coolant.
• Mix Ratio: 50/50 prediluted or 1:1 concentrate mixed with distilled water.

Capacity by Engine Option

The Kenworth W900 is a heavy-duty truck and can be equipped with various engines, primarily from Cummins and PACCAR (which are often rebadged Cummins engines). The cooling system capacity will vary slightly depending on the engine model, radiator size, and other installed accessories like auxiliary heaters.

Always consult your vehicle's owner's manual or the engine manufacturer's specifications for the precise coolant capacity for your specific configuration.

Flush Interval

For a 2018 Kenworth W900, the coolant flush interval is significantly longer than for passenger vehicles due to the use of Extended Life Coolants (ELC). However, it's crucial to monitor the coolant's condition and maintain it properly.

• Normal Duty: Typically 3 years or 300,000 miles (480,000 km), whichever comes first, for ELC coolants. Some ELCs can last longer with proper testing and the addition of extenders.
• Severe Duty (e.g., heavy hauling, frequent idling, extreme temperatures): It is advisable to test the coolant annually or every 100,000-150,000 miles (160,000-240,000 km) and potentially flush sooner if testing indicates a breakdown of additives. Using a coolant extender at recommended intervals can prolong the life of the coolant.

Regularly check the coolant level, condition, and pH using test strips. If the coolant appears cloudy, discolored, or contains contaminants, a flush should be performed immediately regardless of mileage or time.

How to Refill & Bleed

Refilling and bleeding the cooling system on a heavy-duty truck like the Kenworth W900 requires careful attention to ensure all air is removed, which is critical for proper cooling and to prevent hot spots.

1. Safety First: Ensure the engine is cool. Wear appropriate personal protective equipment (gloves, eye protection).
2. Drain System: Open the radiator drain cock and any engine block drains (if present). Allow all old coolant to drain completely.
3. Flush (Optional but Recommended): For a thorough flush, once drained, close the drains and refill with distilled water. Run the engine with the heater on until it reaches operating temperature, then drain again. Repeat as necessary until the drained water is clear. For heavy contamination, a chemical cooling system cleaner may be used following product instructions.
4. Refill: Close all drains. Begin filling the system slowly with the specified 50/50 ELC coolant through the radiator fill neck or expansion tank. Filling slowly helps prevent air pockets.
5. Bleed Air:
   • Start the engine and run it with the heater on high. Keep the radiator cap off (or expansion tank cap loose) and observe the coolant level.
   • Some Kenworth W900s, especially with certain engines, may have a dedicated bleeder valve on the thermostat housing or upper radiator hose. Open this valve slightly to allow trapped air to escape until a steady stream of coolant emerges. Close it once coolant flows consistently.
   • Squeeze the upper and lower radiator hoses repeatedly to help dislodge air bubbles.
   • Maintain the coolant level in the radiator or expansion tank as the thermostat opens and the system accepts more fluid.
   • Continue running the engine and monitoring the temperature gauge. Look for consistent coolant flow in the radiator (if visible).
6. Final Check: Once the engine reaches operating temperature and no more air bubbles appear, top off the coolant to the specified level, install the radiator or expansion tank cap, and check for leaks. Drive the truck for a short period, then recheck the coolant level in the expansion tank when the engine is cool and top up if necessary.

For best results and particularly with large, complex cooling systems like those found in the W900, a vacuum-fill tool can be highly effective in drawing a vacuum on the system and pulling coolant in, minimizing air pockets.

Common Cooling System Issues

Given the demanding nature of heavy-duty truck operation, the 2018 Kenworth W900 can experience several cooling system issues, some of which are common to the entire generation of heavy trucks:

• Coolant Leaks: Due to vibrations, age, and temperature extremes, hoses, radiator tanks, water pump seals, and heater cores can develop leaks. Regularly inspect for drips or visible coolant residue.
• Radiator Clogging: Debris (dirt, bugs, leaves) can accumulate between the radiator fins, reducing airflow and cooling efficiency. Internal clogging from degraded coolant or casting sand can also occur.
• Thermostat Failure: A stuck-open thermostat will prevent the engine from reaching operating temperature, leading to reduced fuel efficiency. A stuck-closed thermostat can cause severe overheating and engine damage.
• Water Pump Failure: The water pump circulates coolant. Bearings can fail, leading to noise or leaks, or the impeller can erode, reducing flow.
• EGR Cooler Leaks: For engines equipped with Exhaust Gas Recirculation (EGR), the EGR cooler can be a common point of failure, leading to coolant entering the exhaust stream or combustion chamber. This can result in coolant loss, white smoke, or engine damage.
• Radiator Cap Issues: A faulty radiator cap won't hold proper pressure, leading to lower boiling points and potential coolant loss due to evaporation.
• Degraded Coolant: Over time, even ELC coolant degrades, losing its anticorrosive properties and becoming acidic. This can lead to corrosion throughout the cooling system and premature component failure. Regular testing and maintenance are crucial.

Addressing these issues promptly is vital to prevent costly engine damage. Regular preventative maintenance, including coolant testing and visual inspections, is key to a healthy cooling system.

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