1989-1993 Dodge 5.9L Cummins Valve Train Parts

The valve train on the 1989-1993 RAM 5.9L Cummins

The first-gen 5.9L Cummins is an overhead-valve inline-six with two valves per cylinder, twelve in all, opened by a solid-lifter camshaft through pushrods and rockers. With no hydraulic lifters to take up clearance, lash adjustment is routine maintenance rather than a repair. Bore is 4.02 in and stroke 4.72 in, and the engine governs at about 2,700 rpm. This collection also carries the piston and ring parts used when an engine goes back together.

What goes out of spec

Lash drifts on a solid-lifter engine. When it does, you may hear ticking or notice a rough idle and lost power, and if lash closes up, exhaust temperatures climb. The schedule is every 24,000 miles or 24 months, set cold at 0.010 in intake and 0.020 in exhaust, with the locknuts torqued to 18 ft-lb. There are two methods: start at cylinder 1 TDC, or use the quick method, then rotate the engine 360 degrees to set the second group. A 1993 D250 that reached 620,000 miles on an untouched long block had nothing done to it but regular valve adjustments.

Stock replacement vs. upgrade

At stock power, the valve train needs lash adjustments and, during a rebuild, new valve stem seals, pistons and rings. Heavier valve springs come in when you add an exhaust brake or a bigger turbo. A documented W350 runs 60 lb springs, and other first-gen builds use Hamilton Cams springs and pushrods. For the bottom end, a documented high-output 1993 engine went together with stock-compression MAHLE cast pistons, shot-peened factory rods with ARP rod bolts and a fire-ringed block.

What we carry

Hamilton Cams: 07-s-001 performance 12-valve springs, 07-s-002 dual valve springs and 07-p-002 extreme duty pushrods. XDP: the XD389 performance valve springs and retainer set, XD314 street performance 3/8 in pushrods and the XD3015RA milled rocker arm pedestal set. BD Diesel: 1030060 60 lb valve springs. MAHLE: top-hat style and standard valve stem seal sets, pistons with rings in standard, .020 and .040 oversize, and piston ring sets in standard and .020. Cummins: the genuine standard piston kit.

Fitment notes

The springs, pushrods, pedestals and valve stem seals here are listed 1989-1998, the full 12-valve run. Pistons are narrower: the MAHLE pistons with rings are listed 1991-1993 and the Cummins piston kit 1991.5-1998, so confirm fitment before ordering pistons for a 1989 or 1990 engine. The MAHLE ring sets cover 1989-2002. Oversize pistons and rings are for a bored block; match what the machine shop measured. When you rotate the engine for lash, never do it with the timing pin engaged, because it will break off in the front cover. Use a barring tool or a 22 mm socket on the alternator nut.

Frequently asked questions

What are the valve lash specs for a 1989-1993 5.9L Cummins?

Set cold: 0.010 in intake and 0.020 in exhaust, with the adjuster locknuts at 18 ft-lb. Do it every 24,000 miles or 24 months. Plan on six new valve cover gaskets each time the covers come off.

When do I need heavier valve springs?

When you add an exhaust brake or a bigger turbo. This collection has 60 lb springs from BD Diesel plus performance and dual springs from Hamilton Cams and XDP. Tell us your turbo and brake setup and we will help you pick.

Will these pistons fit a 1990 truck?

Check first. The MAHLE pistons with rings here are listed 1991-1993 and the Cummins kit starts at 1991.5, so neither listing covers a 1990 engine on its face. The MAHLE ring sets are listed 1989-2002. Call us with your engine details before you order.

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.