Older trucks wear Dodge badges and newer ones say Ram, but the diesel heavy-duty trucks share a Cummins inline 6 at their core. RDI Power services every generation in Brooksville, from a 1990s 12-valve to a current 6.7, along with the Ram 1500 EcoDiesel and Ram chassis cabs. Gas Hemi trucks are outside what we do.
Cummins generations and their weak spots
5.9L 12-valve (1989 to 1998)
Mechanical injection, with the Bosch P7100 pump on 1994 to 1998 trucks. Watch for the killer dowel pin, a timing cover dowel that can back out and drop into the gear train, and for tired lift pumps.
5.9L 24-valve (1998.5 to 2002)
Electronic VP44 injection pump. VP44 failures are often tied to low fuel supply from a weak lift pump, so we measure supply pressure before condemning the pump. Some engines from these years use the so-called 53 block casting, which is prone to cracking.
5.9L common rail (2003 to 2007)
The Bosch CP3 pump and common rail injectors arrive here. Injector wear and fuel supply problems are the usual suspects, and a fuel system that has ingested water or dirt needs the whole path checked, not just a single injector.
6.7L (2007.5 and newer)
Every 6.7 carries a DPF; pickups added DEF and SCR for 2013. The repeat items are EGR valve and cooler faults, a variable geometry turbo that sticks when soot builds up in its vanes, NOx sensors and DEF system faults. Oil leaks are covered in our post on common 2014 Ram oil leaks, and the engine itself on our Cummins service page.
Ram 1500 EcoDiesel
The 3.0L EcoDiesel V6 is a different engine from the Cummins, with glow plugs, EGR, a DPF and DEF. EGR cooler problems are a known concern on these trucks, so we check recall status before quoting that repair.
Ram chassis cabs
Ram 3500, 4500 and 5500 chassis cabs carry flatbeds, dump bodies, service bodies and wreckers. Their 6.7 Cummins is rated differently from the pickup version and often sits behind the Aisin automatic. Long idle hours with a PTO running and heavy loads on short routes make regen health, cooling and brake wear the priorities on these trucks, along with the upfit wiring the body adds.
Chassis and driveline on Ram HD trucks
- Death wobble: a violent front-end shake after a bump at highway speed, caused by worn track bar bushings, ball joints or tie rod ends on the solid front axle. A new steering damper can mask it for a while; it does not fix it.
- 68RFE automatic: behind most 6.7 pickups. Fluid temperature under tow and fluid condition tell us a lot before we ever pull a pan.
- Aisin 6-speed: used on high-output 3500s and chassis cabs.
- G56 6-speed manual: clutch and dual-mass flywheel wear on hard-working trucks; see clutch repair.
Transmission rebuilds are covered on our transmission repair and rebuild page.
Why WiTECH matters
WiTECH is the Stellantis dealer diagnostic platform. With it we get full access to every module, factory flash updates, configuration when a module is replaced, and guided tests that generic tools cannot run. Newer Rams also have a secure gateway that blocks many functions to aftermarket scan tools, so dealer-level access is the difference between diagnosing a Ram and guessing at it.
Ram symptoms not to ignore
- A hard start, long crank or rough idle when cold
- A turbo that whistles differently, or power that fades on a pull
- DEF or DPF warnings, or regens coming more often
- A steering shake after bumps, or wandering on the highway
- Transmission slipping, flaring between gears or running hot while towing
Call with the year, the engine and what you are noticing. We will diagnose it with WiTECH, document the findings with photos, and lay out a straight plan before any work starts.