Arnott Europe provides readers of PMM with a handy guide to how air suspension systems can go wrong.
Air suspension systems rely on multiple components working together. A small, unnoticed air leak can lead to consequential damage and higher repair costs. Here’s how to identify issues, confirm leaks, and address the root cause before more significant problems arise.
Air springs contain flexible rubber bellows that hold pressurised air, which supports the vehicle’s weight. The compressor and valves regulate and distribute the pressurised airflow to ensure the correct ride height. Over time, the rubber can lose elasticity, especially in cold or dry conditions. Furthermore, road debris can puncture the air sleeve, and salt and oil leaks from struts and shocks can degrade the rubber, thereby shortening the lifespan of the air springs.
When cracks or tears form, air escapes from the damaged areas. As air pressure drops, the affected corner, or sometimes the entire front or rear, will sit lower because the air spring no longer has enough air to support the weight. A vehicle sitting unevenly after being parked overnight is a clear sign of a leaking or cracked air spring or a problem elsewhere in the system.
Diagnosing air leaks
A quick test is to start the vehicle:
If the car is auto-levelling again, the issue is likely in the air spring or airline rather than a fault in an electronic component.
If it stays low or uneven, this could be caused by an aging compressor, issues with air distribution due to a non-functioning solenoid valve, or a faulty ride height sensor signal.
For a more precise leak check, use the soap-and-water test. Spray the solution around the folds of the air spring and watch for bubbles; these indicate escaping air and confirm a leak.
Unchecked leaks put extra strain on the entire system. One of the first components to feel the impact is the compressor, which may start running excessively in an attempt to maintain pressure.
Compressor symptoms
A compressor that runs more frequently than normal could be a sign of a leak as well. In most cases, the pressure reservoir delivers the pressure to the air springs, after which the air compressor runs to restore the pressure in the reservoir. When air escapes, the pressure drops, and the system constantly signals the compressor to compensate.
Excessive use can overheat the compressor, damage or even melt airlines, and trigger other system issues. Check for burnt smells, discoloured parts, or heat marks on the compressor housing. Another reason for a defective compressor is a continuously running compressor due to a sticky relay.
Mechanic’s advice:
Always find the root cause before replacing the defective compressor. Always replace the compressor relay when replacing a compressor, as it can get worn or sticky, which can lead to early failure of your new compressor.
Understanding how leaks can be detected and how other system components react helps technicians diagnose problems quickly and prevent repeated failures.
Tip: Regularly inspect air springs for cracks, dry spots, or contamination from oil or road debris. Preventive replacement can avoid further damage to your air suspension system.
