Cadillac Repair: !992 Cadillac Eldorado, cadillac eldorado, air shocks

Question
After I start my car there is a motor type noise that seems to be coming from near the rear wheel on the drivers side. I believe this to be the leveling mecnanism. However, it does not seems to go off. Is it supposed to go off once the car is level?

Answer
This would be possibly the air pump for the air shocks running due to either a broken air supply line to one of the air shocks or a faulty HEIGHT SENSOR.

QUESTION: after the car sits overnight or for a long period of time, Does the back of the car appear to be much lower than the front ?.

It is possible that you are possibly hearing the fuel pump in the gas tank.

Without personally hearing this sound, A diagnosis is most impossible unless you can determine if it is the air pump or the fuel pump.