I've owned a 98 Ford Expedition 4.6 L SOHC for about 6 months. Of course there are problems with it due to age, but so far its served me well as a large vehicle. One of these problems is that the air compressor for the suspension sometimes runs when the car is off. Sometimes I come back to my parked car to hear the compressor running even after 3 hours of sitting. It is not constant, but more of an on and off thing. This occurs more often on a non-level surface. You can visually see that the back of the car sags a bit, especially on the rear passenger side when the car is off. When the car starts, the air compressor gets kind of loud and the back of the car rises slightly.

Yesterday it wouldn't start. The car wasn't started for 2 days prior to this. It is my belief that the air compressor may have drained the battery. Since this is the first time this has happened I think I'm going to replace the battery, but I don't want the compressor to keep turning on while the car is off. Is there a simple fix to this? Could I just pop out a fuse when its off?

I don't plan on sinking much money into this. I just want it to be able to start up and not have to worry about the battery draining. I barely drive it 10 miles/week. Just looking for a possible quick fix to keep from having this problem again. Thanks!

 

Sounds like you have a leak in the air suspension. Could be air lines, solenoids, or the air springs themselves. The latter one is very expensive to fix. Try to find the leak, then plan the next step. If the air springs are bad, you could opt for converting it to coil springs, there are lots of cheap conversion kits to buy.

 

Upon more thought, I realize that the driver's airbag light comes on. Also there is sometimes a "hissing" sound from the rear passenger side to the point I thought the tire was punctured...but that must be the leak. Not sure how to check or replace, because I have very little experience working on cars. I have a mechanic friend coming out today to check it out.

Update: The rear suspension is obviously lower than it should be, however I was able to charge up the battery and has been fine. Rear lifts enough to drive. I think I just wont let it sit for more than a day without starting it up again. Bought a portable jumper device in case it happens again. For a 98 Ford, its not all that bad.

 

Instead of simply fixing the air line leak?

 

I just had this problem with my 97. The passenger rear air spring was deteriorated and was leaking. Compressor was trying to keep it inflated and killed the battery. When the bag was inflated you could see the steel belts where the outer rubber had flaked off.
I bought a replacement pair for $275 and had them replaced in 1.5 hr. These are very easy to replace and require almost no tools.
I like my air suspension and would rather fix it than convert it.


The old bag:





Both sides looked like this but only one was leaking.

 

Thanks for that picture. I'll be getting a new truck soon so I'm not really interested in fixing this much. Is there a way to completely cut the power to the compressor? I'm pretty sure its not functioning anyway as its pretty loud and makes the truck shake.

 

You would want to swap the rear suspension over to the conversion... Just eliminating the use of the compressor will cause your rear end to sit lower than the front which alters the drivability and can cause your rear tires to wear out faster as well.

 

You don't want to drive the truck with the suspension deflated, it's scary. If you want to resale it for a reasonable amount you will have to do something to the suspension, either replace the bags/fix the leak or convert the suspension to springs.
The noise from the compressor is probably just the isolators which are a cheap fix. (Sounds like a jackhammer under the hood.)
If your issue is just a leaking air bag and isolators it would be cheaper to fix than convert. If you are not planning to keep it long you can just replace the leaking bag and let the other side wait.