2003-2004 Dodge 5.9L Cummins Exhaust Manifolds

The exhaust manifold on the 2003-2004 Ram 5.9L Cummins

From the factory, the common-rail 5.9L Cummins uses a one-piece cast-iron manifold that feeds the Holset fixed-geometry turbo. Cast iron grows and shrinks with every heat cycle, and over the years that movement is what cracks it. ATS goes further and calls the manifold the single most restrictive point in the exhaust system, which matters on a truck that tows or has been tuned.

What fails and why

Cracks. Diesel Hub calls cracked manifolds relatively common on 5.9L Cummins turbodiesels, caused by cyclic expansion and contraction of the cast iron. Listen for ticking or knocking that rises with rpm, look for soot at the joints, and pay attention to exhaust smell in the cab. It is age and heat-cycle related and comes on faster on tuned trucks.

Warpage and pulled bolts. As the manifold warps and shrinks, it pulls the bolts and lets the manifold-to-head gasket leak. That shows up as an exhaust leak at the head and broken manifold bolts. Repair it promptly so the crack does not keep spreading.

Stock replacement vs. upgrade

A new one-piece cast manifold restores the factory setup, flaw included. Diesel Hub lists aftermarket multi-piece manifolds with slip joints as the fix: the sections expand and contract but slip along the joints instead of cracking. BD and ATS both build that style. One-piece stainless manifolds are the other route, built so heat cycles do not damage them. The ATS Pulse Flow uses high-silicon-moly iron with roughly 30 percent larger internal diameter in critical areas. Whatever you choose, plan on new gaskets and new studs or bolts, since warpage pulls on the hardware and broken bolts are part of this failure.

What we carry

Manifold parts from our exhaust lineup, sorted by job:

• Manifolds: the ATS Diesel Performance Pulse Flow exhaust manifold kit and the BD Diesel 1045987 exhaust manifold, both listed for 2003-2007 Cummins.
• Gaskets: the Mahle MS19225 manifold gasket set, the BD 1045986 gasket set and its -T4 and -T6 kit versions, and the ATS 204-004-2218 manifold-to-cylinder-head gasket.
• Studs and bolts: Gator Fasteners heavy-duty stud kits in black oxide or chrome, Fleece Performance Engineering stud kits with a 7 mm external hex head or a 4 mm Allen socket head, PPE stud kits and bolt-and-spacer kits, the BD 1045982 bolt-and-spacer kit, the Mishimoto MMEXH-RAM-94SK stud kit, and the XDP XD230 stainless bolt kit.
• Turbo adapters: the BD 1044106 T3-to-T4 manifold adapter flange and the ATS 213-045-1000 45 mm wastegate adapter.

Fitment notes

For the Dodge Ram 2500 and 3500, not the Ram 1500. Most of the stud and bolt kits are cataloged across a wide span of 5.9L and 6.7L Cummins years, but manifolds and turbo-side parts need a closer look. An older 1998.5-2002 manifold bolts to the 2003-2004 head but relocates the turbo, which drags in intake, downpipe and oil-line changes. The turbo-outlet side also changed at 2004.5 with the HE351CW. Verify by VIN, use the fitment checker, and remember we install everything we sell at our Wildwood, FL shop.

Frequently asked questions

Should I replace the studs or bolts when I replace the manifold?

Plan on it. Manifold warpage pulls on the bolts, and broken manifold bolts are part of the same failure. Fresh hardware from Gator Fasteners, Fleece, PPE, BD, Mishimoto or XDP means the new manifold and gasket are not depending on fasteners that already took that abuse.

Why choose a slip-joint manifold over a new stock one?

A one-piece cast manifold cracks from thermal cycling, and a new one has the same design. A multi-piece manifold slips at its joints as it heats and cools, which is what keeps it from cracking. It is the fix Diesel Hub lists for this problem.

Can I put a 1998.5-2002 manifold on my 2003-2004?

It will bolt to the head, but it moves the turbo. That means changes to the intake, downpipe and oil lines, so it is not a simple swap. A manifold listed for 2003-2007 avoids that extra work.

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.