How many quarts of coolant does a 6.7 Cummins take?
About 24–28 quarts (roughly 6–7 gallons) is typical for a full system fill—this includes the radiator, engine block, heater core, and hoses. Exact capacity varies by year, radiator configuration, and whether the degas bottle is counted separately.
This article explains the standard ranges, how they differ by model year, and practical steps to measure and refill the cooling system safely. It also provides guidance on verifying the correct coolant mixture and bleeding air from the system.
What affects the total coolant capacity
Cooling system capacity isn’t a single fixed number; it depends on hardware layout and design variations over years.
- Engine block and cylinder head volume
- Radiator size and total coolant volume in the core and hoses
- Heater core size and plumbing
- Degas bottle (expansion tank) capacity and inclusion in total
- Thermostat housing and upper/lower hose connections
- Model year and configuration (engine revisions, cooling system updates)
Because of these factors, the exact total can vary by production year and vehicle spec. Always check the vehicle’s service data for your exact VIN.
Estimated capacities by year and setup
Different generations used slightly different radiators, reservoirs, and hose layouts. Here are approximate ranges for common Ram 6.7L Cummins configurations:
General ranges by generation
- 2007–2012 (first-generation 6.7L): roughly 26–28 quarts
- 2013–2018 (second-generation with updated cooling): roughly 24–28 quarts
- 2019–present (latest updates): roughly 23–27 quarts
Note: These are approximate ranges. Exact capacity depends on radiator size, heater core, and whether the degas bottle is included in the calculation. Consult the OEM service manual or dealer specs for your exact VIN.
How to safely measure and refill the system
To ensure you fill to the true capacity and purge air properly, follow these steps:
- Park on a level surface and wait for the engine to cool to avoid scalding.
- Place a drain pan under the radiator drain valve and drain the old coolant.
- Optionally, flush the cooling system to remove debris and old coolant buildup.
- Measure the amount of coolant you drained to estimate the total capacity; this helps verify the full-system fill.
- Prepare a 50/50 mix of pre-mixed coolant and distilled water unless your coolant is already pre-mixed per the owner's manual. Use the manufacturer-recommended coolant type.
- Refill slowly, then run the engine with the radiator cap off to bleed air; top off as needed once the thermostat opens and flow is established.
- Check the reservoir levels after the engine cools, and top off to the recommended marks if necessary.
- Dispose of used coolant according to local regulations and avoid mixing different coolant types.
Following these steps helps ensure proper cooling system function and prevents overheating due to air pockets or incorrect coolant concentrations.
Bottom line and practical advice
In practice, plan for roughly 6 to 7 gallons (24 to 28 quarts) for a full fill on a 6.7 Cummins, but verify the exact spec for your year and configuration in the owner’s manual or service data.
Summary
The 6.7L Cummins cooling system generally holds about 24–28 quarts for a full fill, with exact capacity depending on model year, radiator size, and whether the degas bottle is counted. Always consult the official manual for your specific vehicle and follow proper bleeding and coolant-mix procedures to maintain optimal engine temperature and longevity.
