5.9L 12-valve Cummins
Dodge introduced the original 12-valve Cummins diesel for their Ram pickups in 1989. It was used in two different pickup body styles and proved to be a powerful and reliable engine that is still sought after today.
Luke’s Auto Repair and Diesel offers a wide variety of maintenance and repair services for the 12-valve Cummins. Whether you need the fuel filter changed, an oil leak repaired, or a hard starting problem diagnosed, we are here to help. The 12-valve Cummins suffered from the “Killer Dowel Pin” problem.
A dowel pin installed between the front gear housing and the engine block can work loose over time and drop into the gears, possibly jamming them and causing major engine damage. We offer a kit that will keep the dowel pin in place and prevent this from happening.
If you are looking for more power from your 12-valve Cummins, Luke’s Auto Repair and Diesel is here to help. We offer performance lift pump systems to keep your fuel system clean and well supplied, and stud kits to prevent head gaskets from blowing. If you’re looking for a simple cold air intake or
performance intake elbow, or a major upgrade, such as a bigger turbo, over-stock injectors, or a performance injection pump, we are your source.
5.9L 24-valve Cummins
In 1998, Dodge debuted an upgraded 24-valve Cummins diesel in their Ram pickups. It offered more power than the 12-valve before it, and came with an electronic control system for enhanced engine
control and improved emissions. With the right maintenance and upgrades, this engine can be a dependable powerplant for your work truck or tow rig.
One of the most common failures on this version of the Cummins is the Bosch VP44 injection pump. This is often due to low fuel pressure from a weak or dead electric lift pump. We offer full diagnostic and repair services for the VP44 and its control system. We also offer aftermarket lift pumps that are
substantially more reliable than the factory units. We can add an additional fuel filter before the lift pump for extra protection. Complete performance lift pump systems, as detailed in the section below,
provide substantial benefits for this engine.
We provide full maintenance and repair services for the 24-valve Cummins. If you need the fuel filter changed, an oil leak repaired, or a hard starting problem solved, we are here to help. We offer injector and turbo replacements, and check engine light diagnostics. We also service the other systems on the truck, such as brakes, steering, suspension, transmission, and transfer case.
If you are looking for more power from your 24-valve Cummins, we can help. We offer performance lift pump systems to keep your fuel system clean and well supplied, and stud kits to prevent head gaskets from blowing. If you’re looking for a simple cold air intake or tuner, or a major upgrade, such as a bigger turbo, over-stock injectors, or a performance intercooler, we are your source.
5.9L common-rail Cummins
The 2003 model year saw the introduction of the common-rail fuel system for Cummins-powered Ram pickups. This advanced fuel system allowed the engine to produce more power and meet newer emissions standards. These trucks can be excellent tow rigs and reliable work trucks for those looking
for substantial power combined with decent fuel economy.
The 5.9L common-rail Cummins suffered from injector problems. Injectors can return more fuel back to the tank than the specifications allow, causing unusually long cranking times, or a no-start condition.
We offer complete diagnostics, testing, and replacement for injectors and injection pumps. We also provide full maintenance services for this engine, including fuel filters, air filters, and coolant flushes.
The electric lift pumps on this engine can fail. We offer aftermarket lift pumps that are substantially more reliable than the factory units. Complete performance lift pump systems, as detailed in the section below, provide substantial benefits for this engine. If the passenger-side engine mount breaks, it can cause the engine cooling fan to cut the wiring to the electronic fan clutch. This can cause engine electronics problems, and lead to failure of the air conditioning compressor due to inadequate airflow over the condenser. We offer complete diagnostics and replacement of the fan clutch and air conditioning system.
If you are looking for better reliability, fuel mileage, or performance from your common rail Cummins, we can help. We offer performance lift pump systems to keep your fuel system clean and well supplied,
and stud kits to prevent head gaskets from blowing. We can also install larger transmission coolers and intercoolers to keep temperatures down while towing. If you’re looking for a simple cold air intake or tuner, or a major upgrade, such as a bigger turbo, over-stock injectors, or a stroker injection pump, we are your source.
The 6.7L Cummins diesel arrived in Ram pickups in the 2007 model year. The newest version brings the highest power output yet, a significant noise reduction (thanks to the advanced injection system), and compliance with the latest emissions standards. With the right maintenance and upgrades, these
trucks can be powerful, comfortable, and reliable towing and hauling vehicles.
Luke’s Auto Repair and Diesel is a full maintenance provider for the 6.7L Cummins. If you need the fuel filters or air filter changed, or the transmission or transfer case serviced, we are here to help. We also offer a wide variety of diagnostics and repairs, including injector and turbo replacements, and DPF
and DEF services. We handle other jobs on the truck, too, such as brakes, steering, suspension, and electrical issues.
The head gaskets on the 6.7L Cummins are prone to blow, even with only small power increases. The driver may notice a loss of coolant with no external leaks, see white smoke coming from the exhaust, or have coolant blowing out of the plastic coolant reservoir. We offer ARP head studs to help prevent the gasket from blowing again. The studs can be installed proactively, without removing the head, before the gasket blows. There is also the option of cutting the head to accept steel o-rings, for additional sealing strength at higher power levels.
Early year models of the Ram pickups with the 6.7L Cummins can suffer from a loose steering feel. Ram used a stronger steering gearbox in newer trucks. This newer gearbox can be retrofitted into the earlier trucks, offering a firmer, more controlled steering feel. Steering looseness on earlier pickups can also be improved with a steering stiffener. This kit bolts across the front of the truck at the stabilizer bar, and prevents the Pitman shaft from wobbling.
Another problem on 6.7L Cummins equipped trucks is lack of air flow through the front air conditioning vents. The evaporator cores can clog with dirt and prevent air movement. The solution is to install air cabin air filter kit. Newer trucks used a cabin air filter from the factory, and it can be retrofitted into early build trucks. Dirt in the air around the truck will now be caught in the filter, keeping the evaporator clean.
If you are looking for better reliability, fuel mileage, or performance from your 6.7L Cummins, Luke’s Auto Repair and Diesel is here to help. We offer performance lift pump systems to keep your fuel system clean and well supplied, and intercooler upgrades to keep you cool under load. If you’re looking for a simple tuner or cold air intake, or a major upgrade, such as a performance turbo, over-stock injectors, or a stroker injection pump, we are your source. We also offer tuning and upgrades for the 68RFE automatic transmission.
Luke’s Auto Repair and Diesel can work with custom tuning companies to provide you with a solution that’s right for your truck. Custom tuning provides several benefits that an off-the-shelf tuner cannot. Custom tunes can be written for your specific truck, with your specific modifications and needs in
mind. An off-the-shelf tuner may not be able to accurately compensate for performance upgrades, such as high-flow intake components or bigger injectors. Using an off-the-shelf tuner with other performance parts may result in a smokey or rough running engine, or in a worst-case scenario, engine damage under heavy loads. Please call or use the contact form if you have questions about custom tuning for your truck.
Performance lift pump systems
Performance lift pump systems, such as those offered by AirDog or FASS, make excellent replacements for a failed factory lift pump, and provide multiple benefits for your Ram Cummins truck:
Longer component life with air separator and fuel filtration
The factory Cummins fuel systems do not have an air separator. AirDog and FASS systems add this beneficial element to your truck and keep air from reaching the injection pump and injectors. The system is designed to compress fuel, not air. If air enters the injectors, it can end up “dry firing,”
essentially slamming internal parts and shortening their life. These performance lift pump systems also include a high-quality fuel filter to remove contaminants before they enter the pump and injectors. This additional filtration can help your fuel system last longer.
High-capacity water separator
AirDog and FASS systems include a water separator with a much larger capacity than what the factory system is equipped with. Water is the single most destructive contaminant in diesel fuel. It reduces lubrication needed for injectors and injection pumps, leading to premature wear or damaged injector tips. It can cause internal rust in the fuel system and freeze inside fuel lines during cold weather. Water also reduces the amount of usable energy in a gallon of diesel, resulting in reduced engine power output. Using a FASS or AirDog system gives you a bigger defense against contaminated diesel, and
helps keep the damage out of your fuel system.
Supports tuners and other modifications
AirDog and FASS systems provide extra fuel volume needed for modifications such as tuners, larger injection pumps, and performance injectors. They can help prevent the fuel rail from running dry and derating the engine.
Diesel Particulate Filter (DPF)
What is a DPF?
Most 6.7L Cummins trucks are equipped with a DPF. The DPF is an emissions control device located in the diesel exhaust system that traps particulate matter created during engine operation. Periodically, the DPF must go through a regeneration, or “regen,” process to burn off the particulates. This requires that exhaust temperatures be very high, often above 1,000 degrees Fahrenheit.
What is required for a regen event to happen?
Temperature is one of the biggest factors. The engine control system must be able to get the exhaust hot enough to initiate a regen. Trucks that make frequent short trips often cannot achieve the proper thresholds. Driving your Cummins on the highway for at least 30 minutes will often allow the system
What happens when a DPF malfunctions?
If the truck fails to complete a regen cycle, or cannot regen often enough, the DPF may begin to fill up and become a restriction in the exhaust system. An improper air/fuel ratio created by a weak turbo, stuck EGR valve, or the wrong tuning can also cause the DPF to fill up quickly. When this happens, the
check engine light may come on, and the driver will often see warning messages, such as “Service Particulate Filter System.” If the condition continues, the control system may limit vehicle speed and power.
How do I fix a clogged DPF?
If you are seeing warning messages or engine trouble codes related to the DPF, please bring your Cummins in for service as soon as possible. If the problem is addressed early, it is often less expensive to fix. Sometimes the problem can be addressed using a professional scan tool to force a regen. General engine control issues, such as turbo and EGR problems, can cause the DPF to clog prematurely. Malfunctioning exhaust sensors can also cause the conditions mentioned above, so accurate diagnostics are important to ensure the problem is solved correctly. Complete DPF replacement may be needed in some instances. Luke’s Auto Repair and Diesel offer a full range of diagnostics and repair services for the DPF system on your Cummins.
Do I need to delete the DPF if I want more power from my Cummins?
No. It is possible to make substantial power gains over stock with the emissions system fully intact using the proper tuning and modifications. A DPF in good condition offers little restriction to the exhaust.
Diesel Exhaust Fluid (DEF)
What is DEF?
Most Cummins trucks had an onboard DEF system by the 2013 model year. DEF is a liquid injected into the exhaust to cause a chemical reaction and aid in emissions compliance. There is a tank mounted in the vehicle that must be filled periodically. The system includes a pump, level sensor, and heater in
the tank, with a line leading to an electronically controlled injector mounted in the exhaust.
What is a DEF heater?
DEF will freeze at approximately 12 degrees Fahrenheit, so the tank contains a heater to ensure proper operation in cold temperatures. The heater is managed and monitored by the engine control system. If it malfunctions, it can set a trouble code and turn on the check engine light.
What happens when the DEF system malfunctions?
When the engine control system detects a fault with the DEF system, it will often turn on the check engine light and/or display a warning message, such as “Service Exhaust Fluid System.” Failures can range from failed DEF heaters to clogged DEF injectors. Luke’s Auto Repair and Diesel offer a full range of diagnostics and repair services for the DEF system on your Cummins truck.
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