Special Tools: Removal & Installation RAM Cab & Chassis 3500 HD

INSTALLATION

Note. The front grommets (1, 3) are a ball stud type mount and the rear grommets (2) are a sliding peg design.

1. Slightly tilt the rear of the engine cover and slide the rear engine cover pegs (2) into the grommets (1) on the rear of the intake manifold until the cover stops. NOTE: While installing the engine cover the front ball studs will make a popping or suction sound as the ball studs are inserted into the front grommets.
2. Lower the front of the engine cover (1) and line up the front ball studs with the grommets (2) on the front of the intake manifold and with a downward motion push the engine cover ball studs into the front grommets.
3. Lightly lift the front of the engine cover to insure the front ball studs are seated into the front grommets correctly.
4. Check to make sure the engine cover is installed properly by reaching behind the cover to verify that the pegs (2) are located in the grommets (1).
5. Install the clean air tube (2) onto the air cleaner housing (4) and the throttle body.
6. Connect the IAT sensor electrical connector (3).

Scheme 42

The Multiple Displacement System (MDS) selectively deactivates cylinders 1, 4, 6 and 7 during steady speed, low acceleration and shallow grade climbing conditions to increase fuel economy.

The MDS can provide a 5 to 20% fuel economy benefit when operating in four-cylinder mode. Depending on driving habits and vehicle usage. For EPA rating purposes the fuel economy is 8 to 15% higher than if the engine was operating on eight-cylinders at all times.

The MDS deactivating lifter (1) can be distinguished from the non-MDS lifter (2) by the disconnecting pin (3) on the side of the MDS lifter.

MDS is integrated into the basic engine architecture requiring these additional components

1. Unique MDS camshaft
2. 8 deactivating roller lifters
3. 4 MDS control valve solenoids
4. MDS control valve solenoid wiring harness
5. Oil temperature sensor

Scheme 43

The Multiple Displacement System (MDS) provides cylinder deactivation during steady speed, low acceleration and shallow grade climbing conditions to increase fuel economy. Both four and eight cylinder configurations have even firing intervals to provide smooth operation. The MDS selectively deactivates cylinders 1, 4, 6, and 7, to improve fuel economy. All deactivated cylinders have unique hydraulic lifters that collapse when deactivated to prevent the valves from opening. Engine oil pressure is used to activate and deactivate the valves. Oil is delivered through special oil passages drilled into the cylinder block. The MDS solenoid valves control the flow. When activated, pressurized oil pushes a latching pin on each MDS lifter which becomes a lost motion link. The base of the MDS lifter follows the camshaft while the top remains stationary. The MDS lifter is held in place against the pushrod by light spring pressure but unable to move because of the much higher force of the valve spring.

Note. It is critical to use the recommended oil viscosity in engines that use MDS.

Deactivation occurs during the compression stroke of each cylinder, after air and fuel enter the cylinder. Ignition occurs, but the combustion products remain trapped in the cylinder under high pressure, because the valves no longer open. No fuel/air enters or leaves during subsequent piston strokes, this high pressure gas is repeatedly compressed and expanded like an air spring.

Scheme 44

Scheme 45

1. Disengage the retaining clamps (1) that secure the air cleaner body cover to air cleaner body.
2. Lift and push the air cleaner body cover toward the engine to disengage the cover locating tabs from the air cleaner body and position the cover out of the way.
3. Remove the air cleaner element (2) from the inside of the air cleaner body (1).
4. Clean out the inside of the air cleaner body (1).

1. Clean any dirt or foreign matter from the inside of the air cleaner housing (1).
2. Install the air filter element (2) into air cleaner housing. Make sure the element is properly seated in the housing.
3. Position the air cleaner housing cover to the air cleaner housing and engage the cover locating tabs.
4. Fully install the air cleaner housing cover to the air cleaner housing and engage the four retaining clamps (1).

Scheme 46

1. Disconnect the make up air hose (3).
2. Remove clean air tube from air cleaner housing (2).
3. Pull the air cleaner housing straight upward to disengage it from the grommets (1).

1. Position the air cleaner housing onto the grommets (1) and push downward.
2. Connect the clean air hose (2) to the air cleaner housing.
3. Connect make up air hose (3) to the air cleaner housing.