Replacing the Power Brake Booster (DSTC)
Replacing the power brake booster (DSTC)
Special tools:
951 2050 BEVEL PROTRACTOR 951 2050 Bevel Protractor
998 5972 JACK 998 5972 Jack
999 5517 SCREW LEFT 999 5517 Screw Left
999 5518 SCREW RIGHT 999 5518 Screw Right
Removal
Remove the cross member between the wheel arches
Note! Cars with SRS: Remove the ignition key to lock the steering wheel. Do not change the position of the steering wheel or front wheels while the steering shaft joint is removed from the steering gear.
Remove:
- the screw and nut in the engine mounting
- the four screws in the wheel arches
- the cross member
- the screw for the oil hose clamp.
Preparations for removing the power brake booster
Switch off the ignition.
Disconnect the connector for the power brake booster.
Remove the vacuum hose from the power brake booster.
Remove the master cylinder
Remove the master cylinder from the power brake booster.
Lift the master cylinder up carefully to avoid damaging the brake pipes.
Pull the brake pipes out of the mountings on the firewall.
Note! Hold the master cylinder in the horizontal position so that no air enters the brake system.
Remove the driver's side soundproofing panel
Remove the nuts for the power brake booster at the pedal box
Remove:
- the retaining clip for the push rod for the power brake booster
- the four nuts securing the power brake booster to the firewall.
Remove the splash guard under the engine
Remove the mounting screw for the cable conduit
The screw is in the sub-frame.
Remove the three cross members under the car
Remove:
- the four screws for thefrontcross member
- the four screws for thecentercross member. Leave the member hanging in the heat deflector
- the two screws for therearcross member. Leave it hanging in the heat deflector.
Remove the locking screw and lock from the steering gear
Note! Do not damage the steering shaft and steering gear when the sub-frame is lowered.
Cars with passenger compartment heaters
Caution! Cars with a passenger compartment heater:Remove the nuts for the passenger compartment heater. The nuts are in a bracket on the left side of the sub-frame.Hang the passenger compartment heater from the bodywork.Remove the fuel line from the clips on the sub-frame and the mounting by the steering shaft.
Preparations for removing sub-frame screws
Cars with turbocharged engines:Remove the charge air pipe from the hose connector at the lower connection for the charge air cooler (CAC).
Heat the charge air pipe when removing it.
Install the tools
Position mobile jack998 5972 JACK 998 5972 Jack under the left-hand side of the sub-frame.
Install 2 screws999 5517 SCREW LEFT 999 5517 Screw Left (bright) on the left hand-side, the front screw with a washer. Install 2 screws999 5518 SCREW RIGHT 999 5518 Screw Right (yellow) on the right-hand side.
Tighten the tools so that they are in contact. Then tighten the nuts on the tools.
Remove the 2 screws from the support bracket by the rear sub-frame screw.
Move the mobile jack to the right-hand side and repeat the procedure.
Lower the sub-frame
Start by lowering the front of the sub-frame by half of the tool thread (1).
Repeat the procedure at the rear end (2).
Now lower the frame to the full length of the tool as described above.
Cars with turbocharged engines:
Check while lowering that the charge air pipe by the lower charge air cooler (CAC) connection does not catch on the radiator
Note! It is important to lower the sub-frame in the right order. Otherwise the steering shaft joint will catch in the lead-in in the bodywork.
Lower the car. Remove the power brake booster
Carefully pull out the master cylinder.
Remove power brake booster.
Note! Keep the seal between the power brake booster and the firewall.
Installation
Transfer the terminals and seals to the new power brake booster
Replace the seal if necessary.
Install the power brake booster with the terminals for the check valve
Install as illustrated.
Tighten the power brake booster
Install:
- the four mounting nuts. Usenew nuts. Tighten to 25 Nm
- the retaining clip for the push rod for the power brake booster
- the soundproofing panel.
Install the master cylinder
Install:
- the master cylinder on the power brake booster. Tighten to 25 Nm
- the brake pipes in the mounting on the firewall.
Note! Ensure that the rubber seal is in position between the master cylinder and the power brake booster during installation.
Install:
- the connectors for level control and the power brake booster
- the clamp with the tie strap around the connector.
Install the connections on the master cylinder
Install:
- the connectors for the level control and the power brake booster
- the check valve
- the clamp with the tie strap around the connector.
Lift the sub-frame
Lift:
- the sub-frame. Use the earlier installed screws999 5517 SCREW LEFT 999 5517 Screw Left and999 5518 SCREW RIGHT 999 5518 Screw Right. Check that the steering shaft joint does not catch in the lead-in the bodywork when the sub-frame is lifted
- the rear edge of the sub-frame (1) halfway along the tool's screw length. Now repeat at the front of the sub-frame (2)
- the sub-frame until its bushings are only a few millimeters from the frame members in same order as above.
Note! It is important that sub-frame is lifted in the correct order.
Install the steering components
Install:
- the steering shaft with the steering gear
- the locking screw. Tighten to 25 Nm
- the locking.
Secure the sub-frame
Position and apply mobile jack998 5972 JACK 998 5972 Jack under the left-hand side of the sub-frame.
Install the screws for the support bracket loosely.
Remove screws999 5517 SCREW LEFT 999 5517 Screw Left and999 5518 SCREW RIGHT 999 5518 Screw Right.
Install the screws for the sub-frame. Use 4newM14 screws. Lubricate the screw threads.
Note! The washer for the front screw.
Transfer the mobile jack to the right-hand side and repeat the procedure as above.
Tighten the screws. Tighten to 105 Nm. Angle-tighten to 120°. Use protractor 951 2050 BEVEL PROTRACTOR 951 2050 Bevel Protractor.
Tighten the support bracket screws. Tighten to 50 Nm.
Install the cross members
Install the front, center and rear cross members. Tighten to 30 Nm.
Install the screw for the cable conduit in the sub-frame.
Cars with passenger compartment heaters
Install the passenger compartment heater
Install:
- the nuts for the heater. Tighten to 30 Nm
- the fuel line in its clips in the sub-frame
- the fuel line holder in the steering gear
- the fuel line in its clips.
Install the splashguard under the engine
Tighten the screws. Tighten to 25 Nm.
Install the cross member
See Brake fluid reservoir, replacing, L.H.D Brake Fluid Reservoir, Replacing, L.H.D.
Checking the power brake booster
See Power brake booster, replacing, L.H.D Power Brake Booster, Replacing, L.H.D.