1993 DODGE D350

Typical onset: 80,000-150,000 mi

Symptoms: Slipping or flaring between 2nd and 3rd gear under load, Burnt transmission fluid smell, dark/metallic fluid, Overdrive clutch failure causing limp mode or no 4th gear, Complete loss of forward gears after towing or heavy use

Fix: The 46RH/47RH was never designed for Cummins torque, especially in heavy-duty use. Rebuild requires upgraded clutches, billet input shaft, and aftermarket valve body for longevity. Expect 12-16 labor hours for R&R and rebuild. Many owners swap to a manual or go aftermarket automatic (47RE or 48RE swap).

Estimated cost: $2,800-4,500

Typical onset: 100,000-200,000 mi

Symptoms: Sudden catastrophic engine failure with loud knocking, Metal shavings in oil, loss of oil pressure, Engine seizes without warning—no prior symptoms in many cases

Fix: A dowel pin in the front timing cover can back out and fall into the timing gears, destroying the gear train and often the entire engine. Prevention is a $200-300 tab kit install (3-4 hours labor). Once it fails, you're looking at full engine rebuild or replacement—short block, crank, pistons, bearings, the works. This is THE known weak point on 1989-1998 12-valve Cummins.

Estimated cost: $6,000-12,000

Typical onset: 120,000-180,000 mi

Symptoms: Hard starting after sitting overnight, long crank times, Loss of power under load, surging at highway speed, White smoke on startup from air in fuel, Truck dies and won't restart until fuel system is bled

Fix: The mechanical lift pump on the Cummins P7100 injection pump fails or develops internal leaks. Fuel lines from tank also crack and suck air. Replace lift pump, check all fuel line connections and rubber hoses from tank to injection pump. Add inline fuel filter and electric lift pump for insurance. 2-4 hours labor depending on line condition.

Estimated cost: $400-900

Typical onset: 100,000-160,000 mi

Symptoms: Grinding or humming noise from front end, increases with speed, Vibration in steering wheel at highway speeds, Wheel play when jacked up, clunking over bumps, ABS light (if equipped) from failing tone ring

Fix: Dana 60 front axle uses unit bearings that wear out from the weight of the Cummins and heavy-duty use. Replace in pairs for even wear. 3-4 hours labor for both sides. Use OEM or quality aftermarket (Timken, Moog)—cheap parts fail quickly under this weight.

Estimated cost: $600-1,100

Typical onset: 80,000-140,000 mi

Symptoms: Transmission fluid leak at radiator or cooler lines, Pink milky fluid in radiator (cooler rupture, fluid mixing with coolant), Transmission overheating, burnt fluid smell, Sagging transmission from broken or torn mount

Fix: Steel cooler lines rust and crack; factory transmission mount tears from engine torque and weight. Cooler line failure is straightforward—replace lines and fittings, 1-2 hours. If cooler ruptures inside radiator, flush both systems and replace radiator (4-6 hours total). Transmission mount replacement is 1-2 hours and cheap insurance.

Estimated cost: $300-1,200

Typical onset: 100,000-180,000 mi

Symptoms: Ticking or hissing sound from engine bay, worse when cold, Exhaust smell in cab, especially with heat on, Visible crack or leak at manifold-to-head junction

Fix: The 5.9L Magnum V8 manifolds crack from heat cycling. Typically passenger side first. Aftermarket headers or quality replacement manifolds required; factory replacements crack again. 3-5 hours labor per side due to tight access. Not a safety issue but annoying and can cause O2 sensor codes.

Estimated cost: $500-900