Removing and installing brake booster hydraulic unit - AR42.10-P-0302A

WARNING: This page does not describe the selected car, but rather 42 other vehicles, including the 1999 Mercedes-Benz S600, 1999 Mercedes-Benz S500, 1999 Mercedes-Benz S420, 1999 Mercedes-Benz S320, and 1999 Mercedes-Benz CL600. However, it is still accessible from the selected car via links, so may be relevant.

MODEL 140.051 /057 with CODE (979) Special protected version

Fig 1: Identifying Brake Booster Hydraulic Unit Components (1 Of 2)

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Fig 2: Identifying Brake Booster Hydraulic Unit Components (2 Of 2)

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

	Removing, installing
1	Release pressure in brake booster hydraulic unit	By removing relays (K37 and K37/1) and pumping the brake pedal at least 30 times until an increase in pedal force can be plainly felt.
2	Disconnect negative battery terminal	The battery is located under the cover in the right side of the trunk.	ra54001400003x
3	Remove engine hood linkage on bodywork panel
4	Remove wiper motor		ra82001400640x
5	Remove splash wall cover under windshield
6	Disconnect left front axle distributor connector in component compartment (X62/7)
7	Remove ABS/ASR unit (A7/3)		ra42001400816x
8	Remove bracket for ABS/ASR unit
	Risk of poisoning from swallowing brake fluid. Risk of injury from skin and eye contact with brake fluid.	Pour brake fluid only into suitable and appropriately marked containers. Wear protective clothing and eye protection when handling brake fluid.	AS42.50-Z-0001-01A
9	Disconnect hydraulic lines (8, 9) Notes on brake fluid	All models	AH42.50-P-0001-01A
10	Disconnect brake fluid indicator lamp switch connector (11)
11	Remove bracket for plastic cover on bodywork panel
12	Remove cover under dashboard and disconnect panic alarm system (PAS) connector		ra68001400150x
13	Disconnect stop lamp switch connector on pedal bracket
14	Unhook and remove pedal return spring (7)
15	Remove retainer (6) on pin (4) and take out pin
16	Unscrew bolts (3)	Replace bolts	*BA42.10-P-1002-05A
17	Remove brake booster hydraulic unit (A7/6) from engine compartment, disconnect cables (10) and push to one side a little	Installation: Ensure that the cables are cleanly routed. Do not crush or trap the cables. When installing the brake booster hydraulic unit, ensure that the fork on the brake booster hydraulic unit is inserted into the brake pedal immediately. Installation: On vehicles with ASR III, swap over charging pump with bracket and install new hose. To install the brake booster hydraulic unit (A7/6), screw two stud bolts M8 diagonally into the end face of the brake booster flange to locate the gasket (2) and to center the unit. Replace relays (K37 and K37/1). As of production 10/97 the relay (K37) is located in front of the engine compartment firewall.
18	Install cable harness		AR54.18-P-0056A
19	Install in the reverse order	Assemble new plug connections (A and C). Carefully assemble connector (C) and ensure that the pins are correctly connected. The cables must not be pushed out of the connector.
20	Fit out vehicle
21	Bleed brake system	See microfiche Model 140 Special Protection
22	Check function of relays		AR54.15-P-3000A

BRAKE MASTER CYLINDER

Number	Designation		Model 140
BA42.10-P-1002-05A	Bolt, brake booster hydraulic unit to firewall	Nm	18