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Call or Text (352) 722-5295Exhaust on the 1989-1993 RAM 5.9L Cummins
The first-gen 5.9L Cummins uses a cast one-piece exhaust manifold that feeds the Holset H1C turbo through a T3 divided flange. From the turbine outlet, a downpipe carries exhaust into a single system that runs under the cab to the muffler. It's a simple layout, and exhaust work on these trucks comes down to five things: the manifold, the pipe, the muffler, the tip and, if you tow, an exhaust brake. The engine has no engine brake of its own, which is why an exhaust brake is such a popular add-on for first-gen owners who pull trailers.
What fails and why
Age and heat do the damage here. The manifold bolts work loose and the gaskets start to leak as the engine heat-cycles over the years. The signs are a ticking at the head, soot streaks around the manifold and exhaust gas temperatures that creep higher than they used to. On hard-worked trucks, and on trucks running more boost than stock, the cast manifold itself can crack or warp. Watch for exhaust leak noise, a loss of boost and visible cracks between the runners. When you chase a leak, check the bolts and gasket first, then inspect the casting closely.
Stock replacement vs. upgrade
If the manifold is sound and only leaking, fresh gaskets and better fasteners are the repair. Multi-layer steel (MLS) gaskets, locking bolts and stainless stud kits are the common choices for 1989-1998 12-valves. If the casting is cracked, ductile-iron replacement manifolds built for the 12-valve exist, including pulse-style designs from BD and ATS; call us and we'll help you weigh the options. Behind the turbo, aftermarket 4 in aluminized downpipe-back systems with 5 or 6 in tips replace the factory pipe and muffler only. For towing, BD makes a vacuum-actuated, switch-controlled exhaust brake for 1989-1998 Dodge trucks.
What we carry
From MBRP you'll find diesel resonators in aluminized and stainless steel, Armor Lite and Armor Plus mufflers, Quiet Tone mufflers in 4 in and 5 in sizes, universal pipe and adapter pieces, and a deep lineup of 4 in inlet tips in rolled, angle cut, straight cut, turndown, dual-wall and black hex styles. BD Diesel supplies exhaust brakes, a manifold gasket set, a V-band clamp and a manual-transmission lever switch. PPE has stainless tips, Mishimoto offers a heat wrap set and a 6 in polished tip, Mahle makes manifold gaskets, XDP has a stainless manifold bolt kit, and ATS offers a 45 mm wastegate adapter for modified turbo setups. Our full exhaust section covers other trucks and builds.
Fitment notes
Read the year range in every title. Several parts here are listed for the whole 1989-1998 12-valve run, the XDP bolt kit spans 1989-2018, and the BD turbo-mount exhaust brake in this collection is titled for 1994-1998 trucks, while BD's remote-mount 4 in brake starts at 1989. Exhaust kits and downpipes for these years are built in separate 2x4 and 4x4 versions. On W250 and W350 trucks, an install video for one 4 in system warns that it may be tight at the transfer case and that hanger holes may need drilling slightly larger. The downpipe also has to match your turbo, since H1C/HX35-style and HX40-style outlets take different downpipes. Automatic trucks with the A518 four-speed, which arrived in mid-1991, need lockup control electronics such as BD AutoLoc or PressureLoc to run an exhaust brake. The earlier A727 three-speed uses a non-lockup converter. When in doubt, verify by VIN.
Frequently asked questions
What causes a ticking sound near the head on a 1989-1993 Cummins?
One known cause is an exhaust manifold leak. On this engine the manifold bolts loosen and the gaskets leak with years of heat cycling, and soot streaks around the manifold are another giveaway. New gaskets plus locking bolts or a stud kit are the standard repair.
Do I need a lockup controller to run an exhaust brake on my automatic?
Only if you have the A518 four-speed, which came in mid-1991. BD says those trucks need its AutoLoc or PressureLoc electronics to control converter lockup with an exhaust brake. The A727 three-speed in earlier trucks uses a non-lockup converter, so lockup control doesn't apply.
Will a 4 in exhaust system fit my 4x4 first-gen?
Yes, as long as you buy the 4x4 version, because kits and downpipes for these trucks are split 2x4 and 4x4. The transfer case is the known snag on W250 and W350 trucks, and one installer notes the hanger holes may need to be drilled slightly larger. If you'd rather not fight it, we install what we sell.
My manifold is cracked. What should replace it?
Look at a ductile-iron manifold built for the 12-valve. BD's pulse manifold is designed to withstand hard use, and ATS PulseFlow and Steed Speed units also list 12-valve fitment. Whatever you choose, install fresh MLS gaskets and upgraded fasteners, and make sure the turbo flange matches the turbo you run.
Why put an exhaust brake on a first-gen?
The 5.9L Cummins in these trucks has no engine brake of its own, so an exhaust brake is how owners add engine braking for towing. BD's brake for 1989-1998 Dodge trucks is vacuum-actuated and switch-controlled, and one is documented on a built 1993 D350.
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.