The diesel people chase. Which version matters enormously — 12V dowel pin, 24V VP44 and the '53' block crack, then the strong common-rail. Transmission and front end are the soft spots.
The 5.9 Cummins is one of the most sought-after diesels ever, but '5.9' covers three very different engines: the mechanical 12-valve, the 24-valve with the VP44 pump, and the later common-rail. Each has its own signature concern, and across all of them the Dodge automatic transmission and front end are the weak links rather than the engine.
The 24-valve's VP44 pump fails, often starved by a weak lift pump.
CHECK Road test for power loss and dead-pedal symptoms and check lift-pump pressure.
Certain blocks cast with a '53' develop an external crack and coolant weep.
CHECK Inspect the passenger side of the block for the '53' casting mark and any crack or seepage.
A dowel pin can back out and damage the timing case.
CHECK Ask whether the known dowel-pin fix has been performed.
The automatic is the weak point, especially behind tuning and towing.
CHECK Check fluid and road test for slip and harsh or missed shifts.
Solid-axle front ends develop a steering wobble.
CHECK Inspect steering and track bar and road test over rough pavement.
Bidirectional OBD-II scan tool · Paint depth gauge · Tire tread depth gauge & DOT date decoder · Brake pad & rotor calipers / measurement tools · Battery & charging system tester · Compression and cylinder leak-down testers · Digital borescope · Floor jack and jack stands …
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Pre-tagged for the Dodge / Ram 5.9 Cummins (1994–2007).