1st gen (1981-1993) Dodge Ram 250 Truck

The Dodge Ram 250 was the medium duty, or three-quarter ton variant of the First Generation Dodge Ram. Introduced for the 1981 model year, the Ram 250 was offered in Standard Cab, Extended Cab (Club Cab), and Crew Cab bodies, and featured rear wheel drive and all wheel drive versions. Trucks fitted with rear wheel drive were designated with the letter ‘D’ or the nameplate ‘Ram,’ while all wheel drive versions were designated with the letter ‘W’ or the nameplate ‘Power Ram.’ A range of gasoline and diesel engines were available for the Ram 250, including V6 and V8 powerplants. The most notable engine option was the 5.9L Cummins turbodiesel. This engine became available from the 1989 model year, and is legendary for its durability. Both manual and automatic transmission options were offered for the First Generation Dodge Ram 250, which was built until 1993, when Dodge introduced the Second Generation Ram.

5.9-Liter Cummins: First Generation (Early 12-Valve, 1989-1993, VE Injection Pump)

Unlike other diesel engines during this time, the 5.9-liter Cummins was the only one that featured direct injection. It didn’t need glow plugs, nor was it naturally aspirated. This hoss was turbocharged (Holset H1C), and consumers loved the powerplant because of its perceived reliability, huge torque output (for the time), and excellent fuel economy. If you can believe it, their 160-horsepower and 400 lb-ft of torque rating was class-leading performance.

The Bosch-built fuel-injection systems found hanging on 5.9-liter Cummins diesel engines have changed several times throughout the I-6 powerplant’s 18-year run. The original 12-valve was equipped with a camshaft-driven, rotary-style injection pump called a “VE” pump. The unit has proven its reliability over the years, but it has the least power potential.

Although there are many ways to increase the horsepower and torque of a VE-equipped 5.9-liter Cummins, it isn’t the most popular pump for performance. With only a few hand tools, fueling can be increased enough to enable the engine to make 70 more horsepower than its stock output, but this injection pump is stingy when it comes to fuel quantity.

Even with the pump cranked up, more conservative fuel injectors present a bigger roadblock to better performance. Luckily, though, there is plenty of aftermarket support for getting more power and torque: upgraded turbos, injectors, as well as internal pump parts like governor springs, fuel pins, and more. Although the VE may leave a lot on the table in terms of performance, VE-equipped trucks with modifications can certainly be made more fun to drive.

  1. These trucks are old. Most of them were produced more than 25 years ago, so don’t expect everything to be in perfect condition
    • injectors
    • injection pump
    • transmission
    • turbo
  2. The ’89-’91 engines were non-intercooled and came with slightly different pistons, injectors, turbos and transmissions (TF727 vs. A518) than ’91.5-’93 versions.
  3. Considerable money can be saved or spent elsewhere once the clutch has been upgraded in trucks with manual transmissions.
  4. Each budget assumes you’re starting new, with a bone-stock and perfectly healthy truck.
  5. Most of the items listed in these budgets are stuff that you and a buddy or novice mechanic could install in a weekend. As such, the labor to have these parts installed has purposely been excluded.

Budget Upgrades

Crank Up the Fuel Screw: FREE

You gotta love mechanical injection, and this mod can net you as much as 70 additional ponies. Cranking up the maximum fuel screw is performed by locating and removing the tamper-proof cover positioned over the fuel screw at the lower, rear side (firewall side) of the VE injection pump, removing the fuel screw’s locking collar and then turning the fuel screw clockwise.

Helpful Tip: Pull the air filter before you perform this mod, because if you turn the fuel screw in too far the engine can run off (i.e. rev until the pump or engine seizes), and you’ll need to snuff out the turbocharger in order to kill the engine (a 2×4 or clipboard will suffice).

3,200 RPM Governor Spring: $20

Trust us, with the early 5.9L Cummins mills being governed around 2,500 rpm from the factory, you’ll be glad to have an extra 700 rpm at your disposal. For just 20 bucks, the 3,200 rpm governor spring from Pure Diesel Power is one of the most beneficial mods you can make to your first-gen Cummins—and the added rpm doesn’t warrant the need for stiffer valve springs.

High-Flow Air Filter: $27

With the 3,200 rpm governor spring installed and higher rpm in the mix, more air flowing through the intake is needed. The FleetGuard AF4555M is the perfect replacement air filter for the job and is also a mainstay in first-gen performance (does not fit ’93 trucks).

Injector Upgrade

Option 1: Prince of Darkness Injectors: $480

Made by Industrial Injection, the Prince of Darkness injectors (or POD’s as they’re often referred) have long been a budget-friendly, entry-level injector option for first-gen owners. They’re known to be a tad on the smoky side, but they provide a 50rwhp bump on the cheap.

Option 2:DDP Stage 3 injectors: $745

Along with the addition of a higher flowing turbocharger, these injectors can push your first-gen into the 400rwhp zone. Available from Dynomite Diesel Products, one of the most trusted names in Cummins injector performance, they flow 55 liters per minute (LPM).

Denny T Stage 1 Fuel Pin: $85

Another well-documented power-adder for the ’89-’93 Dodges is the “Denny T” Stage 1 fuel pin (the fuel pin is also known as the fuel cone) from Denny T Performance. It allows the VE pump to be fueled harder as boost comes up and is typically good for a 30hp, 50 lb-ft of torque gain at the wheels.

Quick note: A lot of folks grind their factory pin to suit their needs, but there is definitely a point of no return once you break out the grinder

Turbo-Back Exhaust System: $275

Although many first-gen owners either build their own exhaust systems or have a local shop do it, Diamond Eye Performance offers fairly affordable 4-inch, turbo-back systems such as this. It’s aluminized, so keep in mind that it won’t last as long as the stainless steel versions, but those of you living in the rust belt can still expect to get a solid 5-6 years of use out of it.

Auto Meter EGT and Boost Gauges with Pillar Pod: $300

While adding easy power to a Cummins is fun, don’t burn down the barn! Get yourself a pyrometer to measure exhaust gas temperature (EGT) and a boost gauge to keep tabs on the turbo. As a general rule of thumb, don’t spend a lot of time above 1,400 degrees on the pyro or allow the turbo to see 35 psi of boost for extended periods of time.

Killer Dowel Pin (KDP) Repair Kit: $65

If you’re willing to pour a couple grand into one of these trucks (or any ’89-’02 model, for that matter), it pays to address the killer dowel pin issue before it’s too late. During assembly at the factory, a dowel pin was pressed into the Cummins’ block in order to locate the timing gear housing. Over time, this pin can work its way loose and cause catastrophic internal damage. At just $65, TST Products offers one of the most affordable killer dowel pin repair kits on the market.

Turbo/Compressor Upgrade

Option 1: 60mm Compressor Upgrade: $285

With plenty of extra fuel in the mix at this point, it’s wise to help the 5.9L breathe a little deeper. Gillett Diesel’s compressor upgrade replaces the factory Holset turbocharger’s compressor wheel with a 60mm inducer version, along with the corresponding high-flow compressor housing (note that ’89-’91 engines were equipped with a 50mm turbo while 

’91.5-’93 engines had a 54mm version). Gains of 30rwhp can be seen with this 30-minute turbo upgrade, along with a 100 to 200 degree drop in EGT.

Option 2: Turbo Upgrade: $1,575

To further improve airflow both in and out of the first-gen 5.9L Cummins, it’s hard to beat the performance a BorgWarner S300 turbocharger provides. For affordability and substantially improved top-end flow, the Super Stock 62/71/14 from High Tech Turbo is a sound, bang-for-your-buck option. The “62” refers to its use of a 62mm inducer compressor wheel, the “71” means it employs a 71mm exducer turbine wheel and the “14” indicates that a 14cm2 turbine housing is used.

AirDog Fuel Supply System: $599

Getting the most out of larger injectors boils down to a strong lift pump. An all-inclusive, compact, 100 gph AirDog fuel system will ensure the VE injection pump sees adequate supply pressure under all driving conditions.

1st Gen 5.9L Cummins Reliability

There are a lot of contributing factors to the impressive reliability of the 5.9L Cummins. The engines were built to be robust, because they were initially created for commercial and agricultural applications. They also lacked modern emissions devices and complex electronics, both of which give greater opportunities for failure. Have you ever heard of the acronym, “KISS”? It stands for “keep it simple stupid”. That’s exactly what Cummins and Ram did. By using an inline-6 engine design, they had less problems because they had less parts. These engines also take up less space than a traditional V8, making it so easy to fix and work on these trucks.

Variations of the 5.9L Cummins are often used in race competitions or sled pulling events because of their ability to take a beating. Here are some of the key features that make these engines so durable.

  • Gear-Driven Components
  • Large Crankshaft & Forged Steel Connecting Rods
  • 7 Main Bearings
  • 6 Head Bolts per cylinder
  • intercooler
  • turbocharger

Key Performance Characteristics

The fuel injection and forced air induction systems play a major role in 5.9L Cummins performance. The 12v 5.9L Cummins was the first engine to deploy direct injection as its fuel injection strategy. It was also the first to offer a turbocharger and an intercooler.

5.9L Cummins Fuel Injection System

Unlike Ford or GM’s 8 cylinder diesel pickups during the same time period, the 12v Cummins used direct injection. Direct fuel injection results in greater efficiency by injecting fuel directly into the combustion chamber. There isn’t any pre-combustion event and it led to noticeable power gains over traditional indirect injection engines.

Illustration from 1993 Ram truck brochure displaying the difference between direct and indirect fuel injection.

Forced Air Induction System

The 1st Gen Cummins was the first 3/4 ton and 1 ton diesel engine to use a turbocharger to increase performance. It was revolutionary for the time, and had a huge impact on drivability and towing capability. Turbochargers increase the amount of compressed air getting to the engine by using exiting exhaust gases. More condensed air means more power, fuel economy, and better towing performance, especially at higher altitudes.

An intercooler was added in 1991 to further enhance the air induction system. Intercoolers cool the compressed air from the turbocharger, creating denser air that enters the engine. Denser air results in a more efficient combustion process. That means greater fuel economy, lower EGTs, and more power. This feature makes the 91.5-93 model year trucks slightly more desirable than 89-91 trucks.

First Gen Cummins Transmissions

The 5.9L Cummins engine could be paired with either a manual or automatic transmission. The Getrag 5-speed manual transmission is the ideal partner to this Cummins engine. It holds up to extra horsepower the best, and with the addition of a performance clutch, it can help make some big numbers. The early automatic transmissions were clunky, and don’t hold up to the extra power as well. They’re also more expensive to fix and rebuild. The two automatic transmissions available on the 1st Gen Cummins are the A727 Torqueflite 3-Speed Automatic and the 4-speed A518, or 46RH, automatic transmission with overdrive. The 46RH is more desirable between the two automatic transmissions as it will allow for much better fuel economy.

Transmission Options 1989-1993 Dodge Diesel Trucks

Take a look below at the chart to see the available transmissions on 1989-1993 Diesel Ram trucks. I included a ranking system to show which transmission is most desirable. The standard transmission on Cummins diesel trucks is 5-speed Getrag 360 and it is also the most desirable.

1st Gen 12 Valve 5.9L Cummins Specs

1st Gen 5.9L 12v Cummins Tow Capacity And Payload

1st Gen 5.9L 12v Cummins towing specs vary depending on cab and model configurations. Max tow capacity for a First Generation 5.9l Cummins is 11,900 lbs. Take a look at your owner’s manual for the exact towing and payload limitations of your vehicle.

1st Generation 5.9L Cummins Maintenance Guide & Parts List

How do I properly Maintain my 1st Gen 12V Cummins Pickup Truck?

If you’re reading this, it probably means you’re the proud owner of a 1989-1993 Dodge Ram D/W pickup truck. These trucks are the first generation of Dodge Ram Pickups available with a diesel engine. The diesel engine in these trucks is no ordinary engine however, they’re one of the most durable diesel engines ever built. Just because they have a reputation for durability, doesn’t mean that you should take a chance when it comes to proper maintenance though. With how easy it is to work on these trucks, there is no excuse for not taking care of one. I’ll cut you some slack though, it’s not easy finding the right parts and your truck might not have come with an owner’s manual. Don’t worry about it. You’ve come to the right place! We make taking care of your truck easy with our comprehensive 1st Generation 5.9L Cummins Maintenance guide.

Our 1st Gen 5.9L 12V maintenance guide gives you the proper service schedule to follow and detailed information pertaining to fluid capacities and specifications. We’ll even give you the exact parts you’ll need and links to where you can find them on Amazon. Assuming you have the parts you need at your home, you won’t have to go the store to pick anything up. All you need is a little bit of mechanical know-how and be willing to learn. If you need to learn a little bit before hand, spend a little time on Youtube. Changing fluids and filters is very easy, even for a beginner mechanic or a DIYer.

When Should I Service My Truck?

If you just bought your 12V Cummins, I would strongly recommend giving it a maintenance overhaul immediately. You don’t know how it was treated in the past. They could’ve worked the truck really hard or used it for work. If it’s a previous fleet vehicle, it probably wasn’t serviced as frequently as it should be. You also don’t know if the previous owner or the dealer you just bought it from used the proper fluids, filters, or engine oil. Don’t take the unnecessary risk! Just go ahead and service the truck as soon as you can.

If you’ve owned the truck for a while, maybe you’re just unsure of if you’ve been following the proper service schedule. Take a look at the mileage of your truck, and see where you’re at in comparison to the chart below. I recommend changing fluids every year or couple of years. Don’t be afraid of performing maintenance sooner than the mileage requirement. Fluids, oil, and parts can lose quality and degrade over time too. It’s better to perform maintenance too soon than being too late. Always keep in mind, the better you treat your truck, the better she will treat you.

What is the Correct 1st Generation 5.9L Cummins Service Schedule?

Follow the 1st Generation 5.9L Cummins maintenance schedule below like your life depends on it. Just remember, there are other parts that could fail that might need to be replaced too. Check out our section about things you should do every oil change to make sure you can catch problems like front end and steering problems early.

Normal Operating Conditions Service Schedule

Severe Operating Conditions Service Schedule

The following chart is the 1st Generation Cummins Maintenance schedule to follow if you frequently tow, idle, or drive in city conditions. If you use your truck for work, or if you beat on your truck, this is the First Gen Cummins service schedule for you.

1st Generation Cummins Fluid Capacity

Another important factor in first generation Cummins maintenance is fluid capacity. You want to make sure you know how much fluid or oil you need to purchase before servicing your truck. The last thing you want to do is drain your truck of fluid or oil, only to find out you didn’t buy enough to properly re-fill your truck. Take a look at our 1st Gen 5.9L Cummins Fluid Capacity chart below.

1st gen known issues/problems

Engine: Tab the KDP; they’ve been known to drop, but more often than not, they stay put. Keep a spare FSS or gut the existing one and use a cable; again, failures aren’t extremely common but when it dies, the truck is useless. Cummins 6BTs are beast. Change your fluids, filters and pressure wash it every now and then and it’ll carry you a million miles, plus.

Transmission: Do the maintenance. Fluid, filters, band adjustments. This stuff is crazy easy but often neglected, then the sorry bastard who owns it blames the machine. If you tow, an auxiliary cooler isn’t a bad idea. If you’re making big power, build it up; they sky’s the limit. You can do everything from a simple bolt-in sprag to adding clutches to the basket to upgrading to a 6-pinion planetary to a billet torque converter to billet input/output shafts.

Electrical: The headlights in these trucks don’t run off of a relay, the switch carries the entire load, and it’s about maxed out as it is. It’s not a bad idea to install a couple of relays. It’ll save you from a failed switch (lights going out in the middle of the night because of an overheated switch or a burned up 14ga wire SUCKS) or worse, a fire. This is a must for supplementary lighting or trailer towing. The super-common speedometer failure which dominoes into the cruise and overdrive going out. 9 times out of 10, the VSS is the culprit. It’s cheap and takes 5 minutes to change. Once in a while it’s the PCM (on intercooled trucks). When it is you have a couple of options: Spend the money and replace it (used computers aren’t too expensive, but it has to be from the same model year) or run a switched ground to the orange wire leading to the VSS. You still won’t have a speedometer but you can actuate the overdrive manually. The only other wiring issue I can think of at the moment isn’t any fault of the manufacturer, rather previous owners. Many people don’t know how to check fusible links or like to splice accessories into wires they have no business touching. It’s very easy to come across a complete hack-job that’s ugly, frustrating and downright dangerous.

Body and frame: Like any vehicle, it depends where it spent time or how it was treated. There are as many clean, rust-free trucks out there as there are Tetanus mine fields. If you’re looking for rust, look in the usual places: rockers, fenders, frame rails, floor boards, etc. Pay special attention to drip rails on the roof. It’s not uncommon to find the frame cracked in the front, left rail at or near the steering gear box. Chrysler alleviated this issue with a stout plate that sits between the two. Otherwise, the sheet metal on these things are plenty tough and hold up despite the bad factory paint.

Other common issues are all small ones. Door hinges wear and sag pretty commonly, steering shaft couplers need rebuilds every few years (or you can buy a Borgeson u-joint shaft and be done with it), valve cover gaskets need to be watched, wiper bushings sometimes need to be replaced, the anti-lock brake system can’t ever be counted on to work, causes a spongy pedal and might as well be deleted immediately. All pretty piddly issues.

As longs as you keep an eye on boost/drive pressures, exhaust gas temperatures, transmission temperatures and do your maintenance, there will be minimal issues. These are man trucks.

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