1994-1998 Dodge 5.9L Cummins Exhaust Manifolds

Exhaust manifolds on the 1994-1998 RAM 5.9L Cummins

The 12-valve 5.9L Cummins left the factory with a cast-iron exhaust manifold and a T3 turbo flange carrying the Holset HX35. Flange standard is the first thing to know when you shop. Stock is T3, most S300 turbo upgrades use T4, and large S400 compound setups use T6. A manifold has to match the turbo that bolts to it.

What fails and why

Cast iron gets brittle as it heats and cools over the years, and cracked exhaust manifolds are not unusual on these trucks. The cracking speeds up on engines that run hot or carry extra fuel. Watch for an exhaust tick on a cold start, soot streaks at the manifold and lost boost. Cracks tend to show up at high mileage or after a lot of time at elevated exhaust temperatures.

Stock replacement vs. upgrade

There are three ways to go. An OEM-style cast T3 manifold restores the factory setup and suits a stock truck. A three-piece manifold, in T3 or T4, uses expansion joints and is the common pick for 500 to 700 hp street trucks; at 1,000 hp it needs a coating rated to 1,700 F. A billet manifold, in T4 or T6, is the heavy-duty option; one billet design carries a lifetime no-crack warranty and tested 200 F or more cooler on exhaust temperature. Whichever you choose, fresh studs and gaskets go on with it.

What we carry

ATS Diesel Performance supplies the Pulse Flow exhaust manifold kit, listed for 1994-2002 5.9L Cummins, and the 213-045-1000 45mm wastegate adapter. For hardware, choose from Fleece Performance Engineering stud kits with a 7mm external hex head (FPE-34771) or a 4mm Allen socket head (FPE-34772), Gator Fasteners EMSK5967C heavy-duty stud kits in black oxide or chrome, the Mishimoto MMEXH-RAM-94SK stud kit and the XDP XD230 stainless bolt kit. Gasket sets come from Mahle (MS10141) and BD Diesel (1045981). This grid also includes transmission parts for the same trucks: the BD 1062003 Stage 3 Transmission Build-It Kit for 1994-2002 Cummins and the ATS 303-002-2188 47RE governor pressure switch, or transducer, listed for 1996-1999.

Fitment notes

Match the manifold flange to the turbo: a T3 manifold for the stock HX35, a T4 manifold for a T4-flange turbo. The stud and bolt kits here are listed through 2018 or later for 5.9L and 6.7L Cummins, but the Mahle and BD gasket sets are listed for 1989-1998, so they are 12-valve parts. A 1998 can be a 12-valve or a 24-valve; look for the P7100 inline pump with a shutoff solenoid on top to confirm the 12-valve. For the governor pressure switch, confirm your truck has the electronic 47RE and not the earlier 47RH.

Frequently asked questions

How do I know my exhaust manifold is cracked?

The usual signs are an exhaust tick on a cold start, soot streaks at the manifold and boost that is down from normal. Cracks are not unusual on the cast 12-valve manifold, especially at high mileage or on a truck that runs hot. Pull the manifold and inspect it, then replace it with fresh studs and gaskets.

Will a T4 manifold work with my stock turbo?

Not directly. The stock HX35 uses a T3 flange, and T4 manifolds are meant for T4-flange turbos such as most S300 upgrades. Match the manifold to the turbo you have, or plan the turbo swap at the same time.

Should I replace the studs and gaskets with the manifold?

Yes. Once the manifold is off, new studs or bolts and a new gasket set are a small part of the job compared with taking it apart twice. Choose Fleece, Gator, Mishimoto or XDP hardware, and a Mahle or BD gasket set made for 1989-1998 engines.

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.