Moses Ludel’s 4WD Mechanix Magazine – How-to: Dodge Ram Truck Air Filter & Fuel Filter Service

How-to: Dodge Ram Truck Air Filter and Fuel Filter Service

Unique gauge on this Dodge Ram air cleaner box measures air flow and air cleaner ability to pass air.

Dodge Ram’s factory gauge measures air flow at the air cleaner box. This indicates the air filter’s ability to move air. As the filter clogs, the gauge moves to the red zone.

Air and Fuel Filtration Needs

     Air filtration is crucial to an engine’s performance and lifespan. A clogged air filter prevents adequate air flow and increases fuel consumption. If the filter does not seal properly, abrasive material seeps into the air stream and damages the pistons, rings and the valves.

As dirty as this filter appears, it was still flowing sufficient air. Don't take a chance—replace it!

     Years ago, when truck engines were all carbureted (gasoline) or mechanically fuel injected (diesel), a clogged air cleaner was obvious: The engine failed to perform well or used excessive amounts of fuel. Today, with EFI/MPI on both gasoline and diesel engines, performance with a dirty air filter is not that easy to spot—until the filter clogs grossly!

     “How often do I change my air or fuel filter?” many ask. This is a difficult question to answer, since both fuel and air flow are quickly affected by contaminants. For the Dodge-Ram truck that drives down washboard gravel roads all day long, an air filter can clog rapidly. A full day’s exposure to alkaline dust can render a pleated paper air filter useless. Dust conditions dictate filter needs.

     Note: Most air filters require regular visual inspections. For some later model Dodge and Ram truck engines, an air-flow gauge allows quick spot-checks of the filter’s ability to flow air.

This fuel filter is contaminated and ready to clog—without many miles on it! Fuel quality and water content impact fuel filter life.

     Fuel filter service intervals are also difficult to determine. Of course, mileage-based OEM recommendations make sense. You will find these intervals listed in the owners manual or a Service Manual for your truck. There are additional variables to consider, too.

     Diesel fuel, for example, can contain high levels of water and particulates. In some regions, diesel fuel and fuel filters suffer from bacterial contamination. 

     With both gasoline and diesel fuel filters, the pleated paper will swell when exposed to water. (That’s how the filter prevents water from damaging the fuel distribution system and fuel injectors.) As little as one bad tankful of water-dense fuel is enough to swell and clog the filter. Often, with little or no notice, the fuel supply shuts off!

     Given the variables, it’s always wise to change air and fuel filters at recommended intervals—or sooner! In your Dodge-Ram truck owners manual, you will find “A” and “B” service schedules listed. These are the minimal time intervals for service.

     If you tow or drive in dusty environments, use the severe-duty service schedule. Unless you drive your truck without a load and along dust-free interstates, the air filter requires steady attention. For fuel filters, always use the severe duty service interval.

  Note: When traveling to remote areas, always carry an extra fuel filter and air filter element—bring the tools necessary for changing the filters!

How-to: Servicing a Dodge-Ram Truck’s Engine Air Filter

     Modern Dodge and Ram truck engines use pleated paper air filter elements. These filters, contained in a plastic air box, are accessible and readily serviced.

The air box fastened with spring clips.

1. Commonly, the Dodge-Ram truck air boxes have a removable top with spring hold-down clips. This illustration shows a spring clip on the ’05 Dodge Ram 3500 turbo-diesel’s air cleaner box. There are usually several clips. Go around the box, loosening clips carefully.

It is practical to remove the air inlet hose in many cases..

2. For this air box, it is easier to remove the top by first loosening the air inlet hose (upper left). This view is the topside of the old air cleaner, which looks clean. See the dirty air filter (further up the page). This is the same filter! Always remove and inspect the intake side of the filter.

Clean the inside of the air box.

3. This is the unfiltered area of the air box. Fortunately, the filter element prevents the abrasive debris and road dirt from entering the engine! This illustrates how important it is to make sure the air filter element seals against the air box flange.

Wipe out and vacuum the air box during service.

4. To prevent quick contamination of the new air filter element, clean out the air box during the filter service. A clean rag and solvent will remove the sooty debris. Dry out and vacuum the box before installing the new air filter.

Our choice for maximum protection is a new Mopar air filter.

5. Our choice for quality filtration and maximum engine protection is the Mopar® product line. For our ’05 Dodge Ram 3500 turbo-diesel, we turn to the Mopar® extreme service, OEM replacement filter.

  Note: Mopar® Performance offers specialty aftermarket filters and systems designed for racing and severe environments, including ram-air induction.

Unique OEM replacement filter offers double lifespan.

6. This is a unique option available for severe duty air filtration. Mopar® offers this as an OEM replacement air filter element. Many truck owners do not know about it…For the ’05 Dodge Ram Cummins turbo-diesel application, the Mopar® quick reference number is MO-249. (The full Mopar number is 53034249AA.) 

     Note: See your Chrysler Group or Dodge Ram Truck dealer. Request the severe-duty option if available for your model and engine application!

Twice the pleated paper surface area in this severe duty option.

7. The difference between the MO-249 filter and the standard OEM filter (top) is dramatic. Added thickness and dense pleats mean far more surface area. This allows the filter to accumulate more contaminants and provides a much longer service life. For long trips across dirt and gravel roads, a severe-duty filter makes the best sense.

     Place the new filter in the air box. Place the lid carefully back into place, making sure the lid seals around the entire filter and air box flange. Fasten the air box spring clips then position hoses and wiring back at their original locations. Be sure the lid fits flush and seals completely.

Clamp screw for air intake hose.

8. This is the inlet hose clamp. The hose is now in its original position on the air box lid. When loosening and tightening the clamp, be certain to restore the hose seal. Prevent dirt from entering the air stream at the engine side of the filter.

  Note: As a safety precaution, carefully position the hose and clamp at the OEM location. In this position, the clamp will conform snugly to impressions and contours, sealing the hose against the air box duct.

The Diesel Fuel Filter Change

   Chrysler-built trucks with gasoline engines and EFI/MPI may not have a fuel filter. (See your truck’s owner manual or a factory OEM Service Manual.) Often, the high output fuel pump has a “sock” filter at its in-tank pickup. There may be a filter/regulator device that does not require periodic service. Such devices usually last the service life of the fuel pump or the pressure regulator.

  Some models do use a replaceable filter. In the case of Cummins turbo-diesel engines, there is always a serviceable fuel filter. Diesel fuel, by its nature, requires ample filtration and even a water trap. This filter must be replaced at regular intervals. If not, the truck’s engine will lose power or stop running without warning.

  Caution: Diesel fuel filters often fail due to water content in the fuel. A single fill-up at the wrong filling station can lead to a clogged fuel filter. It is wise to carry a spare fuel filter on long trips. Know how to replace the filter; bring the needed tools!
  Note: One way to prevent accidental spillage of dirty fuel into the deliver spout of the filter is to drain the fuel filter/water separator
housing before removing the filter. The fuel canister has a drain valve for removing excess water. You can also use this valve to drain the housing of fuel and contaminants before changing the filter cartridge or performing service on the canister, valve or water-in-fuel sensor.
  How to Drain the Fuel Filter Canister:
1. A drain hose is located at the bottom of drain valve. Place drain pan under drain hose.
2. With engine not running, rotate drain valve handle counter-clockwise (rearward) to OPEN and DRAIN position. Hold drain valve open until all water and contaminants have been removed and clean fuel exits.
3. If drain valve, fuel heater element or Water-In-Fuel (WIF) sensor is being replaced, drain housing completely.
Dispose of drained fuel properly.
4. After draining operation, rotate valve handle clockwise (forward) to the CLOSE position.

The Dodge-Ram Cummins truck fuel filter is readily accessible on later applications.

1. The ’05 Dodge Ram Cummins model has an accessible fuel filter canister. Wipe away any debris from the canister lid area before removing the cap! The plastic cap’s built-in hex fitting is 1-1/8″ size. Here, a socket and rachet turn the cap counter-clockwise to loosen it. This is plastic; use care not to damage or round off the hex.

Mopar is our source for a quality replacement fuel filter.

2. Want OEM dependability like your Dodge-Ram truck had when new? Use the Mopar® Cummins-rated fuel filters. Make no substitutes!

     Note: Use the replacement filters recommended by both Chrysler Group and Cummins. Carry spare filters for backcountry travel and long trips!

New fuel filter comes with a new gasket and installation instructions.

3. This filter is Cummins-rated for the turbo diesel. The package includes a new sealing gasket. Follow the provided instructions and carefully fit the filter into the cap clips. The lid clips are plastic and become brittle with age. Twist the filter sideways for removal, using minimal force to protect the tabs…Lube the O-ring as described in the new filter’s instructions.

    Caution: Keep the cap and filter free of debris as you install it in the fuel canister. Tighten with a box-ended wrench or socket and ratchet. Torque as specified, this ’05 cap requires 25 ft-lbs, do not overtighten.
  Note: If there is no torque specification for your fuel filter cap, make it snug enough to compress the new O-ring and stay securely in place. Being plastic, do not over-tighten. Always wipe away spilled fuel and check for fuel leaks.

Need to Prime the Fuel System After the Filter Change?

     After changing the filter, you may discover that the “prime” is gone on the low-pressure pickup side of the system.  (The engine will not start due to lack of fuel in the system.)  This requires priming, and on Dodge Ram/Cummins systems like this 2005 Dodge Ram 3500, the system can be primed by the Chrysler recommended method below. Read these notes carefully and pay close attention to the procedures and safety requirements. If this procedure does not work, see the additional steps provided:

pump. Servicing or replacing fuel system components will not require fuel system priming.
operates for approximately 1 to 2 second and then shuts off.  (Note: When ambient temperatures are cold enough to
1. Turn key to CRANK position and quickly release key to ON position before engine starts. This will operate fuel
transfer pump for approximately 25 seconds.
2. Crank engine. If the engine does not start after 25 seconds, turn key to OFF position, and leave it off for at least
5 seconds. Repeat previous step until engine starts.
3. Fuel system priming is now completed.
4. Attempt to start engine. If engine will not start, proceed to following steps. When engine does start, it may run
cranking intervals.
5. Perform previous fuel priming procedure steps using fuel transfer pump. Be sure fuel is present at fuel tank.

     These steps and cautions are factory recommended for professional service technicians.  If you follow them correctly, you can safely prime the fuel system on a later Dodge Ram Cummins truck equipped with an in-tank priming pump—like our 2005 Dodge Ram 3500.

Earlier Dodge Ram/Cummins Fuel System Won’t Pick Up Prime?  Try the “Bump-Key” Approach!

     Later trucks like our ’05 model have a priming pump at the fuel tank that responds to the factory priming procedure shared above.  On earlier engines without the priming pump at the fuel tank, you can also lengthen the pump priming duration by “bumping” the key switch to the Start position.

     On earlier Dodge/Cummins trucks, try lightly bumping the key to the Start position and quickly releasing the key to the On position—do this twice in a row without allowing the engine to fire.  When the key releases to the On position, this should activate the pickup pump for a 25-second or so interval.  Repeat this priming procedure as necessary, using the light “bump start” approach without actually allowing the engine to fire.  Once you get the sequence down, you can quickly cycle the electric “pickup” fuel pump to prime the entire fuel system.

     This comes in very handy if you do field injector emergency repairs.  It also works when you completely run the engine and fuel tank out of fuel or clog up a fuel filter.  After you change the filter cartridge, if the engine has lost prime, try this method.  Use caution to preserve the starter motor and batteries.

     Caution:  If necessary, allow the fuel pump to cool between pump cycles.  Do not damage the fuel pump when trying to prime the engine! Make sure there is unrestricted fuel flow from the tank, through the lines and through the fuel filter.