If your Mercedes C240 is bouncing or floating quite a bit as you drive, your shocks or struts may have lost internal pressure and have quit dampening the oscillations of your car's body. If the car bounces more than three times when you push down sharply on the corner of the bumper and immediately release it, you will need to replace the shocks or struts. The struts, or MacPherson struts, are located up front and the shocks, or shock absorbers, are in the rear.
Place the jack under one side of the car and lift it until the rear wheel is clear of the ground. Place one jack stand under the frame near the jack and carefully lower the car onto it. Pull the jack out from under the side of the car.
Place the wheel chocks under the opposite front wheel, in front and behind. Open the boot.
Place the jack under the rear axle member and lift, taking up some of the extension of the rear shock absorber.
Pull the interior carpet down in the front corners, exposing the bolts on the tops of the shock absorbers. Remove the nuts on the top of the shock absorbers by turning them counterclockwise, with the 13mm or 14mm socket.
Verify the correct size of the bolt and nut on the bottom of the shock absorber (17mm and 19mm) and remove them, turning the counterclockwise. Lower the rear axle member carefully, until the upper portion of the shock absorber clears the mounting hole. Lift the shock out of the lower bracket.
Insert the bottom of the shock into the bottom shock mount. Insert the bolt and start the nut on the bottom bracket. Prior to inserting the upper portion of the shock, you will need to place the bushing and retainer over the shock rod.
Lift the rear axle member as you guide the shock rod into the upper mounting hole. Place the bushing and retainer over the shock rod and start the retention nut. Tighten the lower mounting bolts to approximately 40 to 50 foot-pounds of torque.
Remove the jack from the back of the car and push it under the side. Lift the car off the jack stand, remove it and lower the car to the ground.
Tighten the upper shock nut to 40 to 50 foot-pounds. If present, run the locknut down and torque it to 40 to 50 foot-pounds also.
Repeat this process on the other side. Replace the boot interior carpet when the job is complete.
Place the wheel chocks in front and behind one of the rear wheels. Loosen the front lug nuts with the lug wrench until they are finger tight. Place the jack under the front frame cross-member and lift the front end up until the front wheels clear the ground. Pull the jack out. Open the bonnet.
Place the jack stands under the front cross-member to each side of the jack pad and carefully lower the car onto them. Remove the lug nuts and front wheels and set the wheels aside.
Verify the size of the three or four bolts on the strut cap and remove them by turning them counterclockwise. Do this on both driver and passenger sides.
Verify the proper size wrench and socket for the two bottom strut bolts and remove them by turning them counterclockwise.
Grasp the strut firmly and pull down and push inward to release it from the shock tower and bottom clamp. Set the strut aside.
Repeat the preceding process on the other side.
Place the strut spring clamp on the uppermost and lowermost spring coils. Using the correct size wrench, collapse the spring as much as you can.
Verify the size of the upper strut nut and remove it by turning it counterclockwise. You may need to use the 13mm wrench to hold the strut rod from turning
Lift the strut cap off the strut coil assembly and pull the strut out of the coil.
Insert the new strut through the coil and place the strut cap over the top. Secure the cap to the strut using the provided upper strut nut. Again, you may need to use the 13mm wrench to provide enough torque to properly secure the strut cap to the strut.
Place the strut under the fender and lift it into place, lining up the holes on the strut tower with the studs on the strut cap. Place the three or four nuts that hold the strut cap to the tower on the strut cap studs and run them down clockwise to finger tight. You will need to hold the strut in place until the nuts are installed.
Twist the strut to line it up with the lower mount on the steering knuckle and insert the two bolts into their holes. If one of the large washers has the hole off-centre, be sure to replace it exactly as it came out, as this adjusts the alignment camber angle.
Torque the bottom strut nut to 50 to 60 foot-pounds of torque. Torque the strut tower nuts to 40 foot-pounds. Replace the wheel. Install the lug nuts finger tight.
Repeat the preceding process on the other side. Place the jack under the front cross-member and lift the car off the jack stands. Remove the jack stands and lower the vehicle until the wheels make contact with the ground. Torque the lug nuts to 75 to 80 foot-pounds.
After replacing the MacPherson struts, you will need to have the car's front end alignment checked and adjusted.
Wear safety glasses. If possible, use a MacPherson strut spring compressor tool, as these come with safety guards.