The 2003-2009 Mercedes Benz E320 Wagon (RWD) is built with the following rear suspension components:
2003-2009 Mercedes Benz E320 Wagon (RWD) Electronic Shocks (x2)- shocks abosrbers whose dampening capabilities is controlled by the suspension control module in order to ensure proper wheel-to-ground contact.
2003-2009 Mercedes Benz E320 Wagon (RWD) Air/Hydraulic Springs (x2)- (models with air suspension only) commonly referred to as air bags, a plastic and rubber bag that is fitted on top of the strut that uses pressurized air as a cushion instead of a metal coil spring to hold a vehicle off of the ground and off of its wheels. These are the number one cause of all air suspension leaks. All air springs all go bad at about the same rate. If one is leaking, the others will not be far behind. For a proper repair, all of them need to be replaced at the same time.. If your model has hydraulic springs/struts, then it is filled with hydraulic fluid instead of air to adjust the height and dampening of the vehicle.
2003-2009 Mercedes Benz E320 Wagon (RWD) Height Sensors (x2)- a linkage located near each wheel of a vehicle with any electronic suspension that, either mechanically or electronically, constantly measures the height of the vehicle, and reports this information back to the control module so that the computer can identify if changes in height need to be adjusted accordingly. The ride height sensor is a moving part, and like all moving parts, they will eventually wear out.
2003-2009 Mercedes Benz E320 Wagon (RWD) Air/Hydraulic Lines- tubes that run from a compressor to the air springs (or a hydraulic pump to the hydraulic springs for models with hydraulic active suspension), which carry pressurized air to the air bags (or hydraulic fluid to hydraulic springs) in order to adjust the height of the vehicle, respectively..
2003-2009 Mercedes Benz E320 Wagon (RWD) Solenoids (x2)- usually L-shaped, these plastic components connect the electrical connection and lines of suspension components to the suspension control module on vehicles with active suspension. The solenoid regulates the air pressure for each air spring. Solenoids start to leak as they wear out causing the vehicle to sag or to lean. This will cause the ride height sensor to send a signal to activate the compressor in an attempt to inflate the air suspension and level out the vehicle. This excessive work load will eventually lead to total failure of the compressor.
2003-2009 Mercedes Benz E320 Wagon (RWD) Compressor Assembly- (models with air suspension only). creates/sends pressurized air to active suspension components. When the air suspension starts leaking, the compressor/pump starts working harder to try to keep the system inflated. By the time air suspension leaks down completely, sitting the vehicle on its tires, the compressor will either have failed or be well on its way to full failure. Buying replacement struts and taking the time to install them only to find out the compressor still needs to be replaced can be very frustrating, time-consuming, and expensive.
2003-2009 Mercedes Benz E320 Wagon (RWD) Hydraulic Pump- if your Mercedes has hydraulic suspension instead of air suspension, then the hydraulic steering pump will also serve as the reservoir for the hydraulic fluid going into the spring bags.
2003-2009 Mercedes Benz E320 Wagon (RWD) Suspension Control Module- a computer which is responsible for the operations of the air suspension system and maintaining the vehicles correct ride height.
2003-2009 Mercedes Benz E320 Wagon (RWD) O-rings- although they are the least expensive parts of the air suspension, they are responsible for maintaining the seal where all of the air lines connect. Be sure to replace the O-rings when repairing any air suspension system.