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October's Cummins of the Month, Pumpkin Spice (fall / halloween), is now open for entries!
A_W907
With good maintenance & purpose a built trans for more power, my truck is at 253,000 miles & running strong. Problem free? No but neither is the "off brand" truck down the street.
Very. My truck has 337k miles on it and not showing any signs of stopping. Just make sure maintenance is kept up, and the manual transmission, stock for stock, are light years better than auto.
I've gotten 330,000 miles out of my 04.5 so far. Has Never left me on the side of the road. Keep up with maintenance and treat it well they will last.
Sounds like you're looking to pick one up. 
The 2003-2007 Dodge Ram trucks equipped with the 5.9L Cummins diesel engine are widely regarded as some of the most reliable heavy-duty pickup trucks from that era. Still, their reliability depends on several factors, including maintenance, usage, and specific model year issues.
The 5.9L Cummins inline-six common rail diesel is renowned for its robust construction and longevity. With the proper maintenance, these engines can last well over 500,000 miles.
2003-2004 Model Years (Early Common Rail):
Fuel System Issues: Early common-rail systems had issues with injector failures and lift pump problems. The in-tank lift pump was prone to failure, which could starve the high-pressure CP3 injection pump, leading to costly repairs. Many owners upgrade to aftermarket lift pumps (e.g., AirDog, FASS) to prevent this.
Transmission Problems: The 48RE automatic transmission in these years is notorious for weak internals, primarily when used for heavy towing or with modified engines. Overheating and torque converter issues are common without upgrades.
"53 Block" Issue: Some 2003 engines had casting issues in the engine block (identified by a "53" stamp), which could lead to cracks. This was rare but catastrophic when it occurred.
2004.5-2007 Model Years:
Improved Fuel System: By 2004.5, Cummins and Dodge addressed many early fuel system issues, making these years slightly more reliable out of the box.
Automatic Transmission: The 48RE remained a weak point, though later years saw slight improvements. Heavy-duty use still requires upgrades.
Front-End Wear: The front suspension and steering components (e.g., ball joints, tie rods, track bar) are prone to wear, especially in 4x4 models or trucks used off-road or for heavy loads. Regular maintenance and upgrades (e.g., aftermarket steering components) mitigate this.
Electrical Issues: Some owners report problems with the TIPM (Totally Integrated Power Module), which controls electrical systems and can fail, causing issues like dead batteries or malfunctioning accessories.
General Wear and Tear and Reliability Factors:
Recommendations for Buyers
Conclusion
The 2003-2007 Cummins diesel trucks are highly reliable when properly maintained, with the 5.9L engine being a standout for durability. However, reliability can vary based on model year (2004.5-2007 preferred), transmission type (manual preferred), and maintenance history. Common issues like automatic transmission (48RE) weakness, front-end wear, and early fuel system problems are manageable with proactive care or upgrades. For buyers in 2025, a well-maintained example with documented history is a solid choice for towing, work, or long-term ownership, but expect to invest in maintenance or upgrades for high-mileage or heavily used trucks.
The 2003-2007 Dodge Ram trucks equipped with the 5.9L Cummins diesel engine are widely regarded as some of the most reliable heavy-duty pickup trucks from that era. Still, their reliability depends on several factors, including maintenance, usage, and specific model year issues.
The 5.9L Cummins inline-six common rail diesel is renowned for its robust construction and longevity. With the proper maintenance, these engines can last well over 500,000 miles.
- Manual Transmissions: The NV5600 6-speed manual is considered bulletproof and highly reliable for heavy-duty use, provided the clutch is maintained.
- Automatic Transmissions: Unless upgraded with aftermarket components (e.g., billet torque converters, valve bodies, etc.) the 48RE automatic transmission is less reliable (I'm being nice here
), especially in high-torque or towing applications.
2003-2004 Model Years (Early Common Rail):
Fuel System Issues: Early common-rail systems had issues with injector failures and lift pump problems. The in-tank lift pump was prone to failure, which could starve the high-pressure CP3 injection pump, leading to costly repairs. Many owners upgrade to aftermarket lift pumps (e.g., AirDog, FASS) to prevent this.
Transmission Problems: The 48RE automatic transmission in these years is notorious for weak internals, primarily when used for heavy towing or with modified engines. Overheating and torque converter issues are common without upgrades.
"53 Block" Issue: Some 2003 engines had casting issues in the engine block (identified by a "53" stamp), which could lead to cracks. This was rare but catastrophic when it occurred.
2004.5-2007 Model Years:
Improved Fuel System: By 2004.5, Cummins and Dodge addressed many early fuel system issues, making these years slightly more reliable out of the box.
Automatic Transmission: The 48RE remained a weak point, though later years saw slight improvements. Heavy-duty use still requires upgrades.
Front-End Wear: The front suspension and steering components (e.g., ball joints, tie rods, track bar) are prone to wear, especially in 4x4 models or trucks used off-road or for heavy loads. Regular maintenance and upgrades (e.g., aftermarket steering components) mitigate this.
Electrical Issues: Some owners report problems with the TIPM (Totally Integrated Power Module), which controls electrical systems and can fail, causing issues like dead batteries or malfunctioning accessories.
General Wear and Tear and Reliability Factors:
- Turbocharger: The stock Holset turbo can wear out over time, especially if the truck is modified for more power. Symptoms include excessive smoke or loss of boost.
- Cooling System: Radiators and intercoolers can develop leaks or clog over time, particularly in high-mileage tow trucks.
- Interior Quality: The Dodge Ram’s interior from this era is not as durable as the engine, with issues like cracked dashboards, worn seats, and rattling trim being common complaints.
- Usage: Trucks used primarily for highway driving or light towing tend to last longer than those subjected to constant heavy towing, off-roading, or performance modifications.
- Modifications: Many owners modify these trucks for more power (e.g., tuners, larger turbos, bigger injectors), which can stress the transmission and fuel system, reducing reliability unless paired with the appropriate upgrades.
- Model Year: The 2004.5-2007 models are generally considered more refined than the 2003-2004 model years due to improvements in the fuel system and other components.
- Mechanic and Owner Insights: Mechanics and owners frequently praise the 5.9L Cummins for its durability but warn about transmission and front-end issues, especially in high-mileage examples. They recommend budgeting for potential upgrades if buying a used truck.
- Market Perception: These trucks hold strong resale value due to their reputation, with well-maintained examples commanding premium prices in 2025. This reflects their reliability when properly cared for.
Recommendations for Buyers
- Inspect Maintenance History: Look for documented maintenance records, especially for oil changes, fuel system service, and transmission work.
- Check for Upgrades: A truck with an aftermarket lift pump, transmission upgrades, or reinforced front-end components is often a sign of a proactive owner.
- Avoid Abused Trucks: Be cautious of trucks with heavy/inappropriate modifications, signs of neglect (e.g., dirty oil, worn suspension), or a history of extreme towing.
- Model Year Preference: If possible, opt for a 2004.5-2007 model with a manual transmission for the best balance of reliability and refinements.
- Pre-Purchase Inspection: Have a diesel mechanic inspect the engine, transmission, and front end. Check for the "53 block" on 2003 models.
Conclusion
The 2003-2007 Cummins diesel trucks are highly reliable when properly maintained, with the 5.9L engine being a standout for durability. However, reliability can vary based on model year (2004.5-2007 preferred), transmission type (manual preferred), and maintenance history. Common issues like automatic transmission (48RE) weakness, front-end wear, and early fuel system problems are manageable with proactive care or upgrades. For buyers in 2025, a well-maintained example with documented history is a solid choice for towing, work, or long-term ownership, but expect to invest in maintenance or upgrades for high-mileage or heavily used trucks.
Sounds like you're looking to pick one up.
Nice .
Definitely asking around….
https://www.cumminsforum.com/threads/2025-reliability.2610740/post-30051808
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Hopefully OP gives himself some time to read.
Truck left stock, the OEM lift pump mounted to the filter housing lasted awhile. My 175k miles is typical.
Hard use and/or modified is where that pump was challenged. It was (and is) easy to change, though.
The in-tank pump considered better, but where, today, can one find OEM equivalent quality? Price of (example) FLEECE unit isn’t wallet-friendly.
What one needs to understand about used Dodge Cummins is that first owner may have been responsible, but by the time sold as used the price attracted those second and third owners enamored of taking a good truck and beating it nearly to death. Tonka toy tires and “mo powah” . . then on to the next victim.
This killed the reliability/longevity of many good examples. Cash for Clunkers, in a sense, is how to think on examining a candidate for purchase. Evidence of abuse is that to which it amounts during a search to eliminate the worst.
— Magazine cover shots of the Wife Beater Tee Shirt Award candidates to sell gangster bling turned many down the wrong road.
The fixes for OEM 3rd Gen are long known. 4WD steering and ball-joint most prominently. Most of the rest is operator-related when failure is genuinely premature.
Age is the severe test. The purchase candidates truly worthy have been garaged. A loving home. That, alone, counters many other problems as it’s not so much appearance, but electrical system reliability which is 80% of all vehicle problems which wind up at a shop. Interior and small parts are the game. Try to find the one without tattoos & piercings, the disease-free example.
Someone else has made the point that both Nv5600 and 5.9L are twenty years past production. And re-man 6.7L + G56 swap looks a whole lot better as a resto-mod than maybe crutching along yet another domestic abuse victim. Which one to obtain and how to run that “computer” would be the question as the 3rd Gen advantage pre-2007 is the emissions simplicity coupled to excellent stock power versus fuel burn (signature).
You want one to live you keep the power turned down (fuel burn is best predictor of reliable longevity against miles in Class 8) and have a plan of use past keeping it under cover and maintenance to date once repairs performed.
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Hard use and/or modified is where that pump was challenged. It was (and is) easy to change, though.
The in-tank pump considered better, but where, today, can one find OEM equivalent quality? Price of (example) FLEECE unit isn’t wallet-friendly.
What one needs to understand about used Dodge Cummins is that first owner may have been responsible, but by the time sold as used the price attracted those second and third owners enamored of taking a good truck and beating it nearly to death. Tonka toy tires and “mo powah” . . then on to the next victim.
This killed the reliability/longevity of many good examples. Cash for Clunkers, in a sense, is how to think on examining a candidate for purchase. Evidence of abuse is that to which it amounts during a search to eliminate the worst.
— Magazine cover shots of the Wife Beater Tee Shirt Award candidates to sell gangster bling turned many down the wrong road.
The fixes for OEM 3rd Gen are long known. 4WD steering and ball-joint most prominently. Most of the rest is operator-related when failure is genuinely premature.
Age is the severe test. The purchase candidates truly worthy have been garaged. A loving home. That, alone, counters many other problems as it’s not so much appearance, but electrical system reliability which is 80% of all vehicle problems which wind up at a shop. Interior and small parts are the game. Try to find the one without tattoos & piercings, the disease-free example.
Someone else has made the point that both Nv5600 and 5.9L are twenty years past production. And re-man 6.7L + G56 swap looks a whole lot better as a resto-mod than maybe crutching along yet another domestic abuse victim. Which one to obtain and how to run that “computer” would be the question as the 3rd Gen advantage pre-2007 is the emissions simplicity coupled to excellent stock power versus fuel burn (signature).
You want one to live you keep the power turned down (fuel burn is best predictor of reliable longevity against miles in Class 8) and have a plan of use past keeping it under cover and maintenance to date once repairs performed.
.
Great truck. 2006 3500 extended cab short box. 210,000 miles and going. 3.73 gears. 4x4. Became a spare truck and doesn’t get as many miles per year as it used to. Don’t want to get rid of it.
Bought it new. Stock other than running a little bigger tires. 285 70 r17. On my 4th set of BFG AT ko2 tres after OEM BFG rugged. Running strong. Re-built 48re trans at in 2014 at 122k miles w upgraded torque converter. Manual would be better.
Ball joints-2nd time upgraded to greaseable Moog-now no issues. Multiple u-joints. Routine other maintenance: brakes, fluid changes. I’m on my 3rd Walker muffler. 5.9 24v w AT still gets 20 mpg doing 70-75mph. I don’t know why but I’m still running OEM shocks (no leaks) but it’s time to change. many,many batteries.
Plenty of times my 2016 3500 Ram 6.7 was in the shop. And, lots more times my 22 Ram 3500
Chassis cab was in the shop for emissions and grid heater stuff. Sold both of them and went back to pre DEF 2006 Reliable Red.
Bought it new. Stock other than running a little bigger tires. 285 70 r17. On my 4th set of BFG AT ko2 tres after OEM BFG rugged. Running strong. Re-built 48re trans at in 2014 at 122k miles w upgraded torque converter. Manual would be better.
Ball joints-2nd time upgraded to greaseable Moog-now no issues. Multiple u-joints. Routine other maintenance: brakes, fluid changes. I’m on my 3rd Walker muffler. 5.9 24v w AT still gets 20 mpg doing 70-75mph. I don’t know why but I’m still running OEM shocks (no leaks) but it’s time to change. many,many batteries.
Plenty of times my 2016 3500 Ram 6.7 was in the shop. And, lots more times my 22 Ram 3500
Chassis cab was in the shop for emissions and grid heater stuff. Sold both of them and went back to pre DEF 2006 Reliable Red.
Rock solid. Still have my old dependable 03 6 speed, 270k miles as my back up truck. Great fuel mileage empty. Never touched the engine other than than regular maintenance. Clutch is getting a little weak but I can’t afford to get rid of it. However wanted a little more comfort features and a little more power and bought a Duramax but I still love that old Dodge. I’ll drive till the wheels fall off. Perfect ranch truck.
Boys recognizing what’s right:
I’m partial to this one
:
Truth is elusive,
Beauty is fleeting,
Nobility is rare.
Maybe it’s not right to assign a pickup truck the characteristics a man needs . . but trust that the boy inside recognizes these attributes. What’s needed.
“ . . I returned, and saw under the sun, that the race is not to the swift, nor the battle to the strong, neither yet bread to the wise, nor yet riches to men of understanding, nor yet favour to men of skill; but time and chance happeneth to them all.”
Drive It Forever.
.
I’m partial to this one
:
Truth is elusive,
Beauty is fleeting,
Nobility is rare.
Maybe it’s not right to assign a pickup truck the characteristics a man needs . . but trust that the boy inside recognizes these attributes. What’s needed.
“ . . I returned, and saw under the sun, that the race is not to the swift, nor the battle to the strong, neither yet bread to the wise, nor yet riches to men of understanding, nor yet favour to men of skill; but time and chance happeneth to them all.”
Drive It Forever.
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