2021 Ram 3500 Coolant Capacity & Type

The 2021 Ram 3500 holds approximately 17-18 quarts (16.1-17 liters) of coolant in its cooling system, depending on the engine. This guide will provide detailed information on coolant capacity, type, maintenance, and common issues for your 2021 Ram 3500.

Quick Answer

• Total Cooling System Capacity: 17-18 quarts (16.1-17 liters)
• OEM Coolant Specification: Mopar Antifreeze/Coolant 10 Year/150,000 Mile Formula OAT (Organic Additive Technology) in purple. Meets Chrysler Material Standard MS-90032 for the 6.4L HEMI and MS-12106 for the 6.7L Cummins Diesel.
• Mix Ratio: 50/50 Pre-diluted or 50/50 concentrate mixed with distilled water.

Capacity by Engine Option

The 2021 Ram 3500 was available with two primary engine options, and their cooling system capacities vary slightly:

Always consult your owner's manual for the most precise capacity for your specific engine configuration.

Flush Interval

Maintaining your cooling system with regular flushes is crucial for the longevity of your engine. The recommended flush intervals for the 2021 Ram 3500 are as follows:

• Normal Duty: Replace initially at 10 years or 150,000 miles (240,000 km), whichever comes first. After the initial replacement, follow the manufacturer's recommended intervals, which are typically every 5 years or 100,000 miles (160,000 km).
• Severe Duty (e.g., heavy towing, extreme temperatures, dusty conditions): Consider more frequent inspections and flushes, potentially every 5 years or 100,000 miles (160,000 km) if you regularly operate under severe conditions. Always refer to your owner's manual for specific severe duty recommendations.

How to Refill & Bleed

Properly refilling and bleeding the cooling system is vital to prevent air pockets, which can lead to overheating. Here's a general procedure for the 2021 Ram 3500:

1. Safety First: Ensure the engine is cool before starting. Wear appropriate personal protective equipment (gloves, eye protection).
2. Drain Old Coolant: Locate the radiator drain plug (petcock) at the bottom of the radiator and open it. Place a suitable drain pan underneath. Open the radiator cap to allow for faster draining. For a complete flush, you may need to drain from the engine block as well; consult your service manual.
3. Flush (Optional but Recommended): Once drained, close the drain plug and fill with distilled water. Run the engine with the heater on high until it reaches operating temperature. Drain again. Repeat this process until the drained water runs clear. Do NOT use tap water for flushing or mixing coolant.
4. Refill: Close all drain points. Slowly pour the specified Mopar OAT coolant (50/50 pre-mixed or concentrate mixed with distilled water) into the radiator. Fill until the coolant level reaches the bottom of the filler neck.
5. Bleeding Air:
   • 6.4L HEMI: Start the engine with the radiator cap off. Squeeze the upper and lower radiator hoses to help dislodge air bubbles. Run the engine at operating temperature with the heater on full blast. Top off coolant as needed. Some HEMI engines may have a bleed screw near the thermostat housing; if present, open it until a steady stream of coolant emerges, then close it.
   • 6.7L Cummins Diesel: The Cummins engine typically self-bleeds effectively. However, after filling, start the engine with the radiator cap off. Allow it to warm up with the heater on high. Air bubbles should rise to the surface. Gently rev the engine a few times to aid in air pocket removal. Keep the coolant reservoir topped off.
6. Final Check: Once the engine is at operating temperature and no more air bubbles appear, install the radiator cap. Let the engine cool completely, then recheck the coolant level in the overflow reservoir and top off if necessary. Monitor the coolant level over the next few drive cycles.

Common Cooling System Issues for This Generation

Owners of 2021 Ram 3500 trucks may experience or should be aware of the following common cooling system issues:

• Leaky Radiator/Hoses: Over time, plastic end tanks on radiators can crack, and rubber hoses can degrade, leading to leaks. Inspect regularly for signs of coolant leaks (puddles, sweet smell).
• Water Pump Failure: The water pump, responsible for circulating coolant, can develop leaks or bearing issues, leading to overheating. Listen for grinding noises or observe coolant drips from the pump area.
• Thermostat Issues: A faulty thermostat can either fail to open (causing overheating) or fail to close (causing the engine to run too cool), impacting engine efficiency and longevity. Symptoms include erratic temperature gauge readings.
• Coolant Contamination: Mixing different types of coolant (especially IAT with OAT/HOAT) can lead to chemical reactions, gel formation, and severe damage to the cooling system and engine. Always use the specified Mopar OAT coolant.
• Diesel Specific Issues (6.7L Cummins): The Cummins engine has additional cooling components like the exhaust gas recirculation (EGR) cooler. Issues with the EGR cooler, such as internal leaks, can lead to coolant loss or contamination.

Regular maintenance and using the correct OEM-specified coolant are the best ways to prevent costly cooling system repairs.

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