2003-2004 Dodge 5.9L Cummins Exhaust Parts

The exhaust on the 2003-2004 Ram 5.9L Cummins

From the head, a one-piece cast-iron manifold feeds a Holset fixed-geometry turbo with an internal wastegate; sources call it the HE341CW or the HY35W. From the turbo, the factory runs 3.5-inch pipe to the front of the muffler, then 4-inch pipe from the rear of the muffler to the tailpipe. The only emissions hardware on this 5.9L Cummins is an oxidation catalytic converter, and every upgrade we talk about here keeps it in place.

The truck changed at 2004.5. The Cummins 600 High Output brought an HE351CW turbo with an electronically controlled wastegate, and the turbo-outlet flange and downpipe changed with it. That is why downpipe, turbo-back and exhaust brake parts are year-specific, and why exhaust part numbers split at 2004.5.

What fails and why

Cracked exhaust manifold. Diesel Hub calls cracked manifolds relatively common on 5.9L Cummins turbodiesels, caused by cast iron expanding and contracting through heat cycles. Symptoms are a ticking or knock that rises with rpm, soot at the manifold joints and exhaust smell in the cab. It is age and heat-cycle related, and it comes on faster on tuned trucks.

Warped manifold and leaking gaskets. As the manifold warps and shrinks, it pulls on the bolts and lets the manifold-to-head gasket leak. You hear an exhaust leak at the head or find broken manifold bolts. Repair it promptly to keep the crack from spreading.

Backpressure in the 3.5-inch section. The stock 3.5-inch section is restrictive on trucks with even mild upgrades or heavy towing. It raises drive pressure and EGT, which shows up as high temperatures on grades and slow spool.

Stock replacement vs. upgrade

A new one-piece cast manifold puts the same design back on the head. The aftermarket answer is a multi-piece manifold with slip joints that expand and contract without cracking, a style BD and ATS both build, or a one-piece stainless manifold made to resist heat-cycle damage. ATS says its Pulse Flow uses high-silicon-moly iron with the internal diameter opened up about 30 percent in critical areas, and that the areas prone to cracking are no longer a problem. Because warpage pulls on the bolts, fresh gaskets and hardware belong in the same job.

Behind the turbo, the compliant upgrade is a 4-inch or 5-inch cat-back system. For towing, an exhaust brake raises backpressure on demand for engine braking and saves your service brakes on long descents. Exhaust brake kits for these trucks come in versions for manual transmissions and for 47RE/48RE automatics, and 2004.5-2007 trucks take different kits, so match the kit to your build date.

What we carry

Here is what this collection holds for the 2003-2004 trucks. Our full exhaust section covers other platforms.

• Manifolds: the ATS Diesel Performance Pulse Flow manifold kit and the BD Diesel 1045987 manifold, both listed for 2003-2007 Cummins.
• Manifold gaskets and hardware: the Mahle MS19225 gasket set, BD 1045986 gasket kits and bolt-and-spacer kits, PPE bolt-and-spacer and stud kits, stud kits from Gator Fasteners, Fleece Performance Engineering and Mishimoto, and the XDP XD230 stainless bolt kit.
• Exhaust brakes and controls: BD Diesel remote-mount exhaust brakes, including the 1027338 4-inch brake listed for 2003-2005 Cummins, plus BD's manual-transmission lever switch and Torqloc torque converter control system.
• Mufflers and resonators: MBRP 4-inch and 5-inch universal 409 stainless mufflers, Armor Lite and Armor Plus models, Quiet Tone mufflers and diesel resonators.
• Tips: MBRP tips with 4-inch inlets in rolled, straight, angle and turndown cuts, PPE 3-inch and 4-inch stainless tips, and a Mishimoto 6-inch polished tip.
• Pipe and fittings: MBRP universal pipe and adapters, a Banks Power 36-inch pipe kit for Banks systems, BD V-band clamps and Mishimoto heat wrap.
• Head sets: Mahle HS54556 and HS54557 head sets, listed for 2003-2007 5.9L Cummins.

Fitment notes

These parts are for the Dodge Ram 2500 and 3500, never the Ram 1500. The big trap is the 2004.5 split: turbo-outlet flanges, downpipes and exhaust brakes differ between the 2003-2004 turbo and the 2004.5-2007 HE351CW, so check every exhaust listing for 2003-2004 fitment. Cab and bed length decide the tailpipe section on a full system, and MBRP lists 2003 and 2004 trucks under separate fitments, so verify by wheelbase. An older 1998.5-2002 manifold bolts to the head but moves the turbo, which means intake, downpipe and oil-line changes. Verify by VIN, use the fitment checker on the product page, or call the shop in Wildwood, FL.

Frequently asked questions

How do I know my exhaust manifold is cracked?

The classic sign is a ticking or knocking sound that gets faster with rpm, along with soot around the manifold joints and sometimes exhaust smell in the cab. Broken manifold bolts point the same way. Fix it promptly, because a crack keeps growing.

Why does the 2003-2004 Cummins crack manifolds?

The one-piece cast-iron manifold expands and contracts with every heat cycle, and over time it cracks or warps. Warping pulls on the bolts and opens up the gasket at the head. It shows up sooner on tuned trucks that run hotter.

Is a slip-joint manifold worth it over a stock replacement?

A multi-piece manifold slips at its joints as it grows and shrinks, which is what keeps it from cracking, and it is the fix Diesel Hub lists for this problem. ATS also opens up the inside of its Pulse Flow by about 30 percent in critical areas, and ATS calls the manifold the most restrictive point in the exhaust.

Will a 2004.5-2007 exhaust brake or downpipe fit my 2003-2004?

Do not count on it. The 2004.5 trucks got the HE351CW turbo, and the turbo-outlet flange and downpipe changed with it. Exhaust brake kits are cataloged by build date and by transmission, so match the kit to your truck.

When does a bigger exhaust make sense?

The 3.5-inch factory section is restrictive, and it shows up on trucks with even mild upgrades or heavy towing as high EGT on grades and slow spool. A 4-inch or 5-inch cat-back system is the compliant way to open it up.

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.