How to Replace the Rear Air Suspension on a 1999 Marquis

The 1999 Mercury Grand Marquis has a built-in air compressor that automatically adjusts the ride height by increasing or decreasing air pressure in the shocks. Before servicing the suspension on the vehicle, the air suspension service switch must be set to "off" so that the vehicle does not try to adjust the shocks while the vehicle is in the air or while the air lines are disconnected. The air suspension switch is located in the trunk of the vehicle.

Instructions

Removal

1

Open the trunk lid and disable the air service suspension by turning the switch to the off position.

2

Lift the rear of the vehicle into the air with the floor jack. Place the first set of jack stands under the rear frame rails of the vehicle. Place the second set of jack stands under the rear axle to prevent any movement when the air shocks are removed. There will be a light hissing sounds as the air is evacuated from the air shocks; wait for the hissing to stop before proceeding.

3

Disconnect the air lines from the air shocks by pushing in on the retainer rings where the air lines connect and pulling the air line from the air line connector.

4

Remove the upper shock mounting nut with a socket and ratchet. Slide the washer and mounting bushing off of the upper shock mounting stud. Remove the lower shock mounting nut with the socket and ratchet and remove the shock from the vehicle.

Installation

5

Place the air shock into its position. Install the washer and lower shock mounting nut and hand tighten the nut.

6

Install the upper shock mounting bushing, followed by the washer and the mounting nut. Tighten the upper mounting nut to 30 foot-pounds of torque with a socket and torque wrench. Tighten the lower shock mounting nut to 66 foot-pounds of torque with a socket and torque wrench.

7

Squeeze the retainer ring for each air line and slide the air lines into position, release pressure on the retaining rings to secure the air lines. Remove the jack stands from under the rear axle.

8

Lift the vehicle into the air with the floor jack and remove the jack stands from under the vehicle frame rails. Lower the vehicle to the ground. Turn the air suspension service switch to "on" and close the trunk. The vehicle should begin to level itself.