Buyer’s Guide: 2003-2007 Dodge RAM 5.9-Liter Cummins Trucks

Every day, people are flooding the internet and even car lots looking for their next truck. When it comes to diesel trucks, we’re hoping to help in your decision making when it comes to the purchase. All truck have pros, all trucks have cons, but some certain year models, engines, and transmission are stuff to keep an eye out for. Today, we’re going to dive into the things to keep an eye out for for the 2003-2007 Dodge Ram truck with the 5.9-liter Cummins.

In 2003, for Dodge trucks, things really made a turn. The Dodge trucks began their diesel venture in 1989 and have become more advanced as the years go on. It started with a VE rotary injection pump, went to the famous mechanical P7100 pump, then to the electronic VP44 pump, and then in 2003, the CP3 was on board.

There are a ton of good things about this year range and this engine combination, but there are also things to be aware of when buying. The 2003-2007 trucks are typically in the price range of first-time buyers, a tow rig, or a usable work truck.

For starters, let’s talk about the drivetrain. Everyone and their brother talks about the Dodge truck transmissions so let’s start there. When you’re buying a used truck, the fact of the matter is, you don’t know what this transmission has been through. Did the previous owner take care of it? Was it properly maintained? Was it abused? You don’t know.

Something that is important when you’re going to test drive a truck, especially with an automatic transmission, is to really pay attention to the transmission’s behavior. A lot of times these will shuttle shift, slip going into gear, delay shifts, and things like that. Since things like this can’t be seen physically, you’re relying on the seat of the pants feel as to whether or not this thing is reliable or not, you know?

On manual transmission trucks, this year range had three different options. The 5-speed NV4500, the 6-speed NV5600, and the 6-speed G56 Mercedes transmission. The NV4500 is a rarity for a manual third-generation truck, but it is possible to find. The NV5600 in the early third-gen trucks are pretty common but after 2006, the G56 pretty much took over. The NV5600 has been known to have synchronizers go bad and the G56 is known for the poor clutch system design.

The dual-mass flywheel system has caused plenty of issues and not to mention, they won’t hold much additional power, either.

So, something to keep in mind, if you’re going to be testing out a manual transmission truck in this range, make sure the gear selector is firmly going into gear with no grinding and make sure on the G56 trucks that the clutches are actually engaging and disengaging.

Something that is talked about on the Ram trucks as much as the transmissions are the front ends. To be honest, there are a lot of transmission issues and failures but I can almost guarantee that 50-percent of these trucks on the road has worn out front ends. It’s as simple as that. So, when you’re inspecting this new truck, you need to start the truck standing still and rock the steering back and forth while someone inspects the steering linkage underneath.

Tie-Rod end links, track bar, and bushings, ball-joints, are all items that are known to be in bad shape. If they are in fact bad, that isn’t necessarily a bad thing. I would say negotiate the repair of these items into the price of the truck or take enough off the price to leave enough money left over to repair.

In 2003, the interior of the Ram trucks changed a lot as far as looks go. But, there a few things that carried over into the third gens that you need to be aware of. For instance, that wear and tear on the driver seat getting in and out will wear that cushion and cover out in no time. Like the second-gen trucks, the dashes can be cracked too. I doubt this is a deal-breaker for you on a truck, but if it is, it’s something to check on.

These has been known for interior electrical issues, too. In fact, the dash displays have had their share of problems as well as the door electronics.

For the exterior of the Rams, one thing comes to mind. Some things never change. You may have heard that saying, “The truck will fall apart around the Cummins engine.” Well, these trucks aren’t much different from the older versions as they have had rust and clear coat issues for some time. Now, if you’re a body guy, no big deal. You can fix this.

There are problem areas for rust on these and that is the rocker panels and even inside door sill. So, if you’re looking for a rust-free truck, take a peek under all of the weatherstrippings, under the doors, and even inside the wheel wells. As for the clear coat, these trucks see a lot of sunlight. Ultimately, that’s not good for the vehicles and will deteriorate the clear over time. Again, if you’re a stickler for perfect conditioned paint, take a climb up and have a look at the roof as the clear may or may not be peeling.

Now, what you’ve all been waiting for, the engine. In 2003, the common rail, 5.9-liter Cummins engine was outfitted in the Ram trucks. This legendary Cummins engine has been nothing but tough, but the new common rail configuration has brought a few issues to keep an eye on. While the common rail system is the preferred route, a rail failure can cause major damage including washing out a cylinder in your engine.

With that risk in mind, the turbo placement on these models being pushed back into the rear two cylinders, that brings up the concern of the additional heat on those two holes. I’m not saying there is an issue with these trucks because of this design, I’m just saying when you’re out looking for a truck, have a peek, have a listen, bring a professional along to check out the wellbeing of the engine.

Another great idea for testing blow-by or whether or not you have a down cylinder or not is to remove the valve cover oil cap and seeing if there is smoke or steam shooting out of the topside of the engine. You may or may not physically be able to see the pressure come out. If not, you can rest the oil cap upside down over the opening and if the crankcase has enough pressure to blow the cap in the air, there is definitely an issue.

If you do end up purchasing a truck in this range and hopefully it was running great with no issues, keep in mind you’ll get out of the truck what you put into it. If you take care of the truck, it will take care of you. Do regular maintenance, put good fuel in it, keep parts changed when needed, and you’ll be very happy with your Ram.

Have anything to add to this? Let us know in the comments below. What truck should we dive into next? Stay tuned to Diesel Army as we will bring you the latest in our industry.

About the author

Artie Maupin

Artie Maupin is from Southeast Missouri and has an extreme passion for anything diesel. He loves drag racing of all kinds, as well as sled pulling competitions.
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