Many modern vehicles, particularly luxury vehicles and SUVs, come equipped with air bag / spring suspension systems. These systems serve the same purpose as traditional suspension shocks and springs, however, they use compressed air in inflatable bags instead of hydraulic fluid in metal tubes. The air bags are inflated by a vehicle mounted compressor to raise the vehicle and increase suspension firmness, while deflating the bags lowers the vehicle and softens the ride. The air springs are made of metal wrapped in a thick rubber coating making them both strong and flexible. While they are heavy duty in build quality, the constant stress of inflation and deflation will eventually cause them to wear out and require them to be replaced. When there is a problem with the air springs, the vehicle will usually display a few symptoms that can alert the driver that there may be a problem.
1. Suspension Sagging
When the air springs are beginning to wear out, they will not be able to provide the support needed to keep the car suspended and level. If one or more of the bags fails or has a problem, this may result in the car sagging in that particular corner or that particular side of the vehicle. A sagging suspension will decrease handling and comfort, and in more serious cases, the vehicle may sag to the point of interfering with the steering and ride characteristics of the vehicle.
2. Constant operation of the air compressor
Another symptom of an air springs problem is a constantly running compressor. If there is damage to the air springs that allows air to escape, then the compressor will attempt to compensate for the loss in pressure by constantly pumping to keep the bags inflated and the system at the correct pressure. If the compressor is constantly running, the system should be examined as soon as possible, as this will put an additional strain on the compressor which may accelerate its wear and cause it to fail.
3. Bottoming out of the suspension
Failed air springs can also cause the vehicle suspension to bottom out. As the air springs are what absorb the impacts and movement of the road, when they fail, the road force is transferred directly to the frame. This will compromise the ride quality of the vehicle when significant road force is encountered, such as when going over bumps or potholes, and will cause the suspension to bottom out.
Because the air springs are what directly support and level out the vehicle, they are very important to the overall handling and ride characteristics of the car. If your vehicle is displaying any of the symptoms of a problem with the air bag, or you suspect that there may be a problem with one or more of the air springs, have the suspension diagnosed by a professional technician, such as one from YourMechanic. They will be able to determine if the car needs its air springs replaced, or if there is another problem that needs to be addressed.
This article originally appeared on YourMechanic.com as Symptoms of Bad or Failing Air Springs and was authored by Ed Ruelas.