What would cause the rear shocks of my 89 Lincoln Mark VII to (quickly) deflate at times and for no apparent reason? As an example, one day the car sat level for 6 hours and then I drove it 2 minutes to a gas station and filled up. While I was in the kiosk the rear end dropped all the way down and once I started it the compressor brought it back up. Another time, while sitting in the car with the radio on, the back end suddenly dropped, then it did again and again, until the suspension bottomed out. I have also noticed the rear left rises higher than the rear right but I have not determined if it stays that way or levels out while driving. My new battery is dead but that may be from something else-the car has been sitting and there may be an yet undetermined draw.
It sounds like you might have a problem in the leveling sensor. This is the sensor that tells the compressor when to come on or turn off. If it is bad you will get the same symptoms that you are describing. This could be part of your battery draw problem as well.
September, 10, 2011 AT 4:12 PM
I did another test: After connecting a new battery I started the car and waited for the rear end to rise. Then I disconnected the battery and waited for it to drop-about 18 hours later. Repeating this test twice more I found the second time it dropped within a couple hours but the third time it didn't drop until about 12 hours later. Each time I did not let the car run any longer than necessary to bring the back end up and I disconnected the battery immediately.
It is as though the system decides to vent air at will!
Could this still be the levelling sensor?
September, 11, 2011 AT 3:18 AM
Yes it could.
September, 12, 2011 AT 7:26 PM
Thanks for the advice. I hope the next owner has better luck with it : )