1998.5-2002 Dodge 5.9L Cummins Engine Components

Engine components on the 1998.5-2002 5.9L Cummins

This is the parts bin for the long block: crankshaft seals, timing case gaskets, the oil pump, cam and crank position sensors, expansion plugs and the valvetrain hardware that bolts to the head. The 24-valve ISB is a cast-iron inline-six with a cast-iron head, a solid-lifter cam and four valves per cylinder. The block is parent-bore with no wet liners, so liner pitting is not something you plan around on this engine. For other systems, start at our Cummins hub.

What fails and why

Start with the block. About 100,000 ISB blocks carry the 53 casting, and on the 1999-2001 blocks the water-jacket walls are thin. Some crack, usually on the passenger side directly below the freeze plugs, and on automatics the crack can hide behind the transmission heat exchanger. Heavy towing, hard throttle before warm-up and overheating are the triggers, and coolant seeping down the side of the block is the sign. If one cracks, Lock-N-Stitch is the accepted repair; welding is discouraged because it hardens the cast iron and spreads the crack.

At the front of the engine, the timing cover locating dowel, known as the killer dowel pin, can back out and drop into the gears with no warning. It is mainly a 12-valve problem but has been noted on some 1999 trucks, so the time to deal with it is when the front cover or crank seal is already off. When you are chasing an oil leak, the crank seals, timing case gaskets and a vacuum pump gasket kit are all here, and the vacuum pump shaft seal is a known leaker on these engines.

Stock replacement vs. upgrade

For a working truck at stock power, factory-grade parts are the right answer: Cummins genuine seals and gaskets, MAHLE seal and gasket sets, Dorman steel cup expansion plugs and genuine or replacement sensors. Upgrades here are for engines seeing more boost and rpm. XDP sells heavy-duty piston oil squirter nozzles, a bolt-on side freeze plug, high-boost valve springs, HD rocker arms and billet valve bridges. Stiffer springs and stronger pushrods are sold for higher rpm, higher boost and exhaust-brake duty. XDP also lists a performance harmonic balancer next to a stock-replacement balancer for 1998.5-2002, so you can go either way.

What we carry

• Seals and gaskets: Cummins front crank seal kits, rear main seals with repair sleeves and timing gear case gaskets; MAHLE rear main and timing cover seals, timing cover gasket kits and lower engine gasket sets.
• Sensors: Cummins cam position sensor, Alliant Power crankshaft position and oil/fuel/coolant temperature sensors, and XDP crank and cam position sensors.
• Front of engine: Cummins camshaft gear and oil pump, Dorman vacuum pump, vacuum pump gasket kit, fan blade and steel cup expansion plugs, and XDP harmonic balancers and balancer bolt sets.
• Valvetrain and studs: XDP rocker arms, trunnion set, billet bridges, pushrods and an X220 head stud kit, plus parts from Hamilton Cams and Fleece Performance Engineering.
• Also here: a Mishimoto replacement oil cooler, and parts from BD Diesel, Gator Fasteners and Wehrli Custom Fabrication.

Fitment notes

Read the year range in every title. Some parts cover 1989-2002, some are 1998.5-2002 only, and some split inside this generation: the Cummins camshaft gear lists 1989-2000, the Cummins dipstick 2001-2002, and the XDP crankshaft position sensor 1998-2001. The 1998.5-1999 and 2000-2002 trucks also differ in several systems, so confirm the half-year. A 2002 Ram 2500 or 3500 is still a second-gen truck, and 2003 common-rail parts do not carry back. Verify by VIN.

Frequently asked questions

Where is the 53 casting number on the block?

Check the passenger side of the block below the injection pump, and sometimes the driver side, for a 53 cast into the iron. It matters on 1999-2001 24-valve blocks; 12-valve blocks with a 53 casting do not share the cracking problem. If you find one, watch the area below the freeze plugs for coolant seepage.

Should I fix the killer dowel pin on a 24-valve?

It is mainly a 12-valve problem, but it has been noted on some 1999 trucks. The dowel can back out and drop into the timing gears with no warning. If the front cover or front crank seal is coming off anyway, that is the time to address it.

Which rear main seal should I buy?

We list a Cummins genuine rear main seal, a Cummins seal with a repair sleeve, and MAHLE rear main seals and seal sets. The sleeved version is meant for a crankshaft whose seal surface has worn. Check the year range in each title, since some span 1989-2018 or later and others are specific to 1989-2002.

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.