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How to Diagnose Bad Air Shocks

by Sameca Pandova

Air suspensions do not actually use air shock absorbers, these systems use large air bladders in place of metal coil springs to allow a vehicle to compensate for heavy loads and regulate vehicle height, while using a traditional shock absorber to provide damping. These systems were used on many Fords, including the Mark VIII and the Continental, but were most commonly seen on Ford's Panther platform (Crown Victoria, Mercury Grand Marquis). Diagnosis of an air system leak involves examining the air bladders and lines, along with testing the compressor to ensure the system is airing properly.

Vent the air suspension down on your car by shutting off the engine, then opening and closing the driver's door. This will results in the suspension venting existing air in the suspension. Once the suspension is lowered, locate the air suspension shut-off switch in the trunk and deactivate the air suspension. Now that the air suspension is disabled, the compressor will not refill the bags.

Run a tape measure from the ground at the center of the wheel, to the top center of the wheel arch, then record the number. After a day or two of driving or letting the car sit, re-measure to see if any wheel is lower than your original recorded number. Measure each corner, and then check the measurements each day until one or more corner is lower. Sometimes an air bladder will not leak at rest, but only when the vehicle is driven and the bladder expands and contracts.

If a corner is lower, that means air as escaped from the system; this is evidence there is an air leak at that corner. The leak can originate from the airbag, the air lines running to the bag or possibly the airbag actuating solenoid. Normally, the compressor will refill the bag, but with the compressor deactivated, the leak will become apparent.

The vehicle is safe to drive with a small leak that the compressor can overcome, but this means that the compressor will be working harder than normal to replace venting air and will cause premature compressor failure if not addressed.

Examine the corner that is lower than the others. You should see rubber air lines that run to the air bladder, check these to see if there is a tear or rip in the line, then visually inspect the air bladder for any damage. Listen carefully to see if you can hear the hissing from an air leak. Using soapy water, liberally spray down the air bladder, then look for bubbles, which are a telltale sign of a leak. If you cannot hear or see a leak, then you will need to start the car and observe the air suspension components in the lower corner while the compressor attempts to re-fill the bladder.

Turn on the air compressor switch and the turn the car to the "ON" position. The compressor will begin to fill the bags to return the car to normal drive height. While this is happening, carefully examine the air bladder assembly again, using soapy water to try to locate a leak, and listening for a hissing sound as air leaks. You can leave the ignition in the "ON" position with the engine off to keep engine noise from making diagnosis more difficult.

Measure each corner to see if the air compressor refills the leaking bag, after the compressor has run for a minute or two. If the bag does not refill, the car remains low at the identified corner, and you cannot detect a leak either audibly or visually, then the air compressor may be dead and require a rebuild, or the leak may be in an air line running to the airbag and not in the airbag itself. You should be able to hear the compressor as it pumps, and you should be able to feel pressure in the air line if you pinch the line where it enters the bladder with your fingers.

Tip

  • Each airbag contains a solenoid usually mounted at the top of the bladder. When the solenoid o-rings go bad, this causes an air leak from the bag. A good independent automotive shop will be able to help you diagnose this possibility. If you are replacing a air bladder, use a fresh set of solenoid o-rings --- do not reuse the old existing o-rings with a new air bladder.

Warning

  • If your car has a serious air leak such that a corner or end of the car has lowered dramatically, it is not advisable to drive the vehicle in that condition for an extended period, as this will prematurely wear out the shock absorbers and place stress on the control arm bushings. In these instances it is advisable only to drive the vehicle to a repair shop or in cases of emergency until the defective parts can be replaced.

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About the Author

Based near Chicago, Sameca Pandova has been writing since 1995 and now contributes to various websites. He is an attorney with experience in health care, family and criminal prosecution issues. Pandova holds a Master of Laws in health law from Loyola University Chicago, a Juris Doctor from Case Western Reserve University and a Bachelor of Arts in history and political science from Case Western.

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