2007.5-2009 Dodge 6.7L Cummins Coolant Tanks

The coolant bottle on the 2007.5-2009 Ram 6.7L Cummins

The 6.7L Cummins uses a pressurized degas bottle to manage coolant expansion in a system that holds about 5.7 gallons. That coolant runs through the block, head, EGR cooler and the water-cooled turbo before it returns through the radiator, and the bottle is where all of it shows up. It is where you check the level, where you add coolant, and where most cooling problems on this truck get noticed first. That makes it the part owners replace when it cracks and the part that tells them when something else is wrong.

What fails and why

The simple failure is a cracked bottle, and a new tank fixes that one. The failure that matters more is coolant pushed into or out of the bottle under load, with bubbles or steam. On this engine that pattern is the classic first sign of a head gasket, most often after an overheat or after power has been added. A level that falls with no external leak can also point to the EGR cooler, a known pattern on DPF-era diesels, though not documented as a 6.7L-specific weakness. A new bottle does not fix either of those, so diagnose before you buy.

Stock replacement vs. upgrade

For a cracked or leaking bottle, a direct-replacement reservoir is the fix, and that is what the tank on this page is. The cap is where owners have a choice: Wehrli's billet aluminum tank cap is the alternative to a stock-style cap. Pick on condition and preference, and remember that neither part changes how the system cools. If the bottle keeps overfilling after you replace it, the bottle was never the problem.

What we carry

Dorman 603-317 is a coolant recovery tank reservoir listed for 2004-2009 5.9L and 6.7L Cummins, which spans the whole 2007.5-2009 6.7L run. Wehrli Custom Fabrication WCF100472 is a billet aluminum coolant tank cap listed for 2004.5-2024 Cummins and 2001-2024 6.6L Duramax trucks.

Fitment notes

The Dorman tank is listed across the third-generation 5.9L and 6.7L years, so a 2007.5, 2008 or 2009 pickup falls inside its range. The 4500 and 5500 chassis cabs use a different chassis where most pickup parts do not interchange, so confirm before ordering for those. When in doubt, verify by VIN or call with the truck's details.

Frequently asked questions

My coolant bottle keeps overflowing. Is the tank bad?

Not necessarily. Coolant pushed into or out of the degas bottle under load, especially with bubbles, is the classic first sign of a head gasket on the 6.7L. Replace the bottle if it is cracked, but diagnose the overfilling first.

Will the Dorman 603-317 fit my 2008 Ram 3500?

It is listed for 2004-2009 5.9L and 6.7L Cummins trucks, which covers a 2008 pickup. If yours is a chassis cab, confirm by VIN first, since the 4500 and 5500 ride on a different chassis.

What coolant goes in the bottle?

The factory fill is Mopar 10-year/150,000-mile antifreeze mixed 50/50 with distilled water, about 5.7 gallons for the full system. If you are changing brands, a full flush is cleaner than mixing products in the same system.

Not sure what fits? Call the shop at the number in the header, or use the fitment checker on any product page. We install everything we sell.