If you've been driving a heavy-duty truck for some time, you may be familiar with the operations of the air compressor. You know that it needs to cycle on or off at certain times to level the suspension and may correctly assume that there is an issue if the compressor's motor is working overtime. What could be going wrong, and how should you proceed?
Focusing on the Airbag
An over-enthusiastic compressor is the first sign of a damaged airbag. In this case, the compressor is trying to generate and distribute air to ensure that the system self-levels, but this work will be futile if there is a hole in one of the bags.
Using the Soap Test
You should begin by looking at all the hoses connecting the system to check for any obvious issues. If you cannot see any problem but one corner of the vehicle is clearly lower than another, it may be time to break out the soap and water. Cover the outer surface of the airbag with soapy water and turn the compressor back on. You should immediately notice the presence of bubbles and pinpoint the location of your problem.
Preparing to Start
Before you can do any work in this area, you will need to isolate the compressor. You can then remove the retainer clips and nuts and disconnect the line from the top of the bag. This should allow you to compress the bellows of the bag to get rid of any remaining air and prepare it for removal.
Looking for the Cause of the Issue
Before you proceed, it's a good idea to work out why the damage occurred in the first place. If you can see evidence of a foreign object that may have pierced the airbag, you may have the answer, but you may also find evidence of a broken fitting elsewhere. This can sometimes happen when you hit a particularly nasty pothole, so don't forget to repair the damaged item. Otherwise, you will just repeat the problem following reassembly.
Handling the Work
Before removing the airbag, you may sometimes need to loosen any protective devices. For example, a heat shield may sit between the suspension and the vehicle exhaust.
Just remember that some parts of the suspension system are pressurised, and you should always follow the manufacturer's guidelines when working in this area. If you'd rather err on the side of caution, entrust the work to a qualified mechanic instead, as they will have the appropriate tools on hand to make their work a lot easier. Further, always use manufacturer-recommended parts whenever you replace a damaged airbag and ancillaries.
For more information about truck suspension, contact a local auto shop.