2021 International MV Coolant Capacity & Type Guide

The 2021 International MV holds anywhere between 25.0 and 40.0 quarts (23.6 to 37.8 liters) of coolant, heavily dependent on whether it is equipped with the Cummins B6.7 or the Cummins L9 engine, as well as the specific chassis and auxiliary equipment upfits. As an ASE-certified master technician dealing with medium-duty commercial trucks, I can tell you that getting the coolant right in these workhorses is critical to maximizing uptime and preventing catastrophic engine failures.

Below is your comprehensive guide to the coolant capacity, specifications, and maintenance procedures for the 2021 International MV.

Quick answer

When servicing the cooling system on your 2021 International MV, keep these primary specifications in mind:

• Total cooling system capacity: 25.0 to 30.0 quarts (23.6 - 28.3L) for the Cummins B6.7, and 32.0 to 40.0 quarts (30.2 - 37.8L) for the Cummins L9 (actual capacity varies based on cab heater core size, auxiliary PTO coolers, and radiator configuration).
• OEM coolant spec: Heavy-Duty Nitrite-Free OAT (Organic Acid Technology) or Extended Life OAT. The coolant must meet Cummins CES 14603 or CES 14439 specifications. This fluid is typically Red in color (such as Fleetguard ES Compleat OAT).
• Mix ratio: A 50/50 mix of coolant and distilled/deionized water. Pre-mixed 50/50 solutions are highly recommended in commercial fleets to prevent mineral scaling from tap water. In extreme cold climates (below -34°F), a 60/40 mix (coolant to water) may be used.

Capacity by engine option

Because the International MV is a highly customizable commercial chassis, cooling system volumes are given in ranges. Always purchase slightly more coolant than the estimated capacity to ensure you have enough for bleeding and topping off.

Note: Chassis equipped with auxiliary rear heaters, PTO coolers, or larger severe-service radiators will push the capacity toward the higher end of these ranges.

Flush interval

Heavy-duty diesel cooling systems require rigorous maintenance to prevent cavitation and liner pitting, though modern OAT coolants have extended these intervals significantly.

• Normal Duty: Replace the coolant every 600,000 miles, 12,000 engine hours, or 6 years, whichever comes first. However, you must use coolant test strips every 300,000 miles or 1 year to check the freeze point and additive depletion.
• Severe Duty: For trucks operating in high-idle situations (like utility bucket trucks or delivery routes), heavy towing, or extreme dusty environments, the interval should be shortened to 300,000 miles, 6,000 hours, or 3 years.

How to refill & bleed

Bleeding the cooling system on a medium-duty truck like the International MV can be tricky due to the large volume of fluid and the routing of heater hoses. Air pockets in a Cummins engine can lead to localized hot spots and cracked cylinder heads.

1. Drain the system: Open the petcock at the bottom of the radiator. Remove the surge tank cap to speed up draining.
2. Pull a vacuum: The absolute best practice for these heavy-duty trucks is to use a pneumatic vacuum coolant refiller (Airlift tool). Attach it to the surge tank, pull a vacuum on the entire cooling system, and hold it to check for leaks.
3. Refill: Let the vacuum draw the 50/50 pre-mixed coolant into the system. This method eliminates 99% of air pockets instantly.
4. Manual Bleeding (If vacuum is unavailable): Fill the surge tank slowly. Open any manual bleed petcocks on the upper engine block/EGR cooler if equipped. Once fluid flows out of the bleeder, close it.
5. Warm-up: Start the engine with the surge tank cap off. Turn the cab heater to maximum heat to open the heater control valves. Run the engine at high idle (around 1,000 - 1,200 RPM) until the thermostat opens and the upper radiator hose gets hot.
6. Top off: Turn off the engine, let it cool slightly, and top off the surge tank to the "COLD MAX" line.

Common cooling system issues

For this generation of the International MV (and the Cummins engines powering them), keep an eye out for a few specific issues:

• EGR Cooler Leaks: The Cummins B6.7 and L9 are known to occasionally develop internal leaks in the EGR cooler. If you are slowly losing coolant but see no external puddles, or if you notice white smoke from the exhaust, have the EGR system pressure tested immediately.
• Coolant Level Sensor Failures: The low coolant level sensor in the surge tank can become coated in sludge or fail internally, throwing a false low-coolant code and potentially derating the engine.
• Radiator End Tank Seeping: Due to the heavy vibration of commercial duty, the crimped seams where the plastic radiator end tanks meet the aluminum core can eventually seep. Inspect these seams during every preventative maintenance service.

Taking care of your truck's cooling system is the cheapest insurance policy against catastrophic downtime. Find a trusted shop on Repairius.