Note: Installation will require new steering gear mounting bolts, tie rod nuts, tie rod ball joint and rubber coupling clamp bolts.
Removal
1. Place chocks under the rear wheels, apply the parking brake, raise the front of the vehicle and place it on stands (see "Lifting the car and placing it on supports").
2. Set the front wheels in the straight-ahead direction and lock the steering wheel using the ignition key.
Note: Do not turn the column with the steering gear removed.
3. On models equipped with power steering, use brake hose clamps to pinch the inlet and return hoses near the steering gear to reduce fluid loss. Label the fittings to avoid confusion during installation, then loosen and remove the nuts on the inlet and return fittings (see Fig. 21.3, a, b). Be prepared to collect any fluid that will leak out when you loosen the nuts. Plug the ends of the hoses and the openings in the steering gear to prevent fluid from leaking out and contaminating the hydraulic system.
Fig. 21.3, a. Steering gear and related parts
1 Steering gear
2 Steering column
3 Longitudinal steering rod
4 Steering rod
5 Hydraulic hoses (supply and drain)
6 Mounting bolts
Fig. 21.3, b. Hydraulic hose fittings of the steering gear (shown by arrows)
4. Using paint or a marker, make alignment marks between the bottom end of the steering column, the rubber sleeve, and the steering gear pinion. Note that on some models, you may have to remove the steering gear heat shields to access the sleeve.
5. Loosen and remove the clamp bolts, then slide the coupling up and onto the steering column to separate it from the steering gear pinion.
6. Loosen the nuts securing the ball joints of the steering rods to the steering knuckle. Separate the ball joints from the steering knuckle, using a universal ball joint puller if necessary.
7. Working from underneath the wheel arch, loosen and remove the three steering gear mounting bolts and pull the steering gear out from under the vehicle.
Repair
8. Check the condition of the steering gear. If repairs are necessary, contact a Mercedes-Benz dealer service station. The only operation that can be easily performed by yourself is replacing the steering gear seal (see paragraph 23).
Installation
9. If a new steering gear is being installed, the steering gear pinion must be correctly positioned before installation.
10. On early models (until 1990.) unscrew the plug and sealing ring on the side of the steering gear, then turn the pinion until the center hole aligns with the plug hole. If there is a special pointed locking bolt, screw it in to securely fix the steering gear pinion (see fig. 21.10).
Fig. 21.10. Steering gear alignment parts - models produced before 1990.
1 Steering gear
2 Piston
3 Gear
4 Fixing bolt
11. On later models (released after 1990) align the mark on the gear with the mark on the steering gear housing (see fig. 21.11).
Fig. 21.11. On later models (after 1990.), To center the mechanism, align the mark on the gear with the line on the crankcase
12. Install the steering gear in place. Align the marks made during removal (the "native" unit) or make sure that the pinion remains correctly centered (new mechanism) and connect the gear with the rubber coupling.
[Original source of information: MercedesMan]
13. Slide the rubber sleeve into place until it stops, then install the new steering gear mounting bolts and tighten them to the required torque.
14. On early models, where necessary, remove the centering bolt and install the plug with the sealing ring on the side of the steering gear.
15. Install new clamp bolts and tighten them to the required torque.
16. Connect the ball joints of the longitudinal and transverse steering rods to the steering arm, then install new mounting nuts and tighten them to the required torque.
17. On models with power steering, connect the hydraulic hoses to the steering gear and tighten the union nuts securely. When finished, fill and bleed the hydraulic system as described in paragraph 25.