Remove/install front axle

AR33.10-P-0100RT

Remove/install front axle

18.02.2020

Model

251

Modification notes

19.10.2011

Value changed: Nut, link rod to front shock absorber

BA32.20-P-1003-02L

Shown on model 251 with engine 113, with panoramic glass sunroof with top sliding sunroof, code 413 and AIRmatic (air suspension with level adjustment and adaptive damping system ADS), code 489

1

Engine compartment paneling

4

Lifting device

2

Underfloor paneling, right

5

Front axle

3

Underfloor paneling, left

6

Protective panels

Shown on model 251 with engine 113, with panoramic glass sunroof with top sliding sunroof, code 413

7

Screw, rpm sensor

15

Plastic caps

10

Cable tie

16

Guide pin

11

Steering knuckle

17

Brake caliper

12

Brake hose bracket

20

Upper transverse control arm

13

Brake hose

L6/1

Left front rpm sensor

14

Clamp

L6/2

Right front rpm sensor

Shown on model 251 with panoramic glass sunroof with top sliding sunroof, code 413

17

Brake caliper

26

Connector

20

Upper transverse control arm

27

Nut, steering knuckle

21

Puller

28

Steering column

22

Link rod

29

Screw, steering coupling

23

Suspension strut

30

Oil lines

24

Threaded connection

31

Retaining plate

25

Nut, link rod

32

Screw, retaining plate

Shown on model 251 with panoramic glass sunroof with top sliding sunroof, code 413

33

Screws, front engine mount

35

Propeller shaft

34

Screws, propeller shaft

36

Screws, front axle carrier

39

Rear centering panel screws

37

Screws, rear axle carrier

41

Bolts

38

Centering plates

42

Centering bores

 

Remove/install

 Danger

Risk of death caused by vehicle slipping or toppling off of the lifting platform.

Align vehicle between vehicle lift columns and position the four support plates at the vehicle lift support points specified by the vehicle manufacturer.

AS00.00-Z-0010-01A

Topical note

Notes on installing brake hoses

AH42.10-P-9406-01A

Topical note

Notes on self-locking nuts and bolts

AH00.00-N-0001-01A

Evaluating steering gear when repairing accident vehicles

AH46.20-P-9409-01A

Notes on AIRmatic

AH32.22-P-1000-02RT

1

When working on the front axle (5), be careful not to scratch, mark or notch the surfaces of aluminum parts. Otherwise the service life of the of the parts will be reduced.

2

Deactivate easy entry/exit function

AR54.30-P-1000-02RT


If the easy entry and exit feature is activated, the steering wheel moves to a different position when the driver's door is opened or closed.
This can cause damage if the steering wheel holding device is installed.

 Only on vehicles with memory package (driver's seat, steering column, mirrors), code 275.

3

Raise vehicle

AR00.60-P-1000RT

4

Remove the front wheels



AP40.10-P-4050RT

5

Deflate front suspension struts using STAR DIAGNOSIS

 Only on vehicles with AIRmatic (air suspension with level adjustment and Adaptive Damping System (ADS)), code 489.

 The vehicle may not be standing on its wheels.

6

Switch off ignition and remove the transmitter key from the EIS [EZS] control unit

 On vehicles with Keyless-Go, code 889: Press Keyless-Go start/stop button repeatedly until the ignition is switched off. Remove transmitter key from vehicle and store it at a location beyond its transmission range (at least 2 m).

7

Open hood, position vertically.

AR88.40-P-1000RT

8

Remove partition wall between wheel wells

Engine 113, 642

AR62.30-P-2400RT

9

Remove engine cover

 Engine 156: Lift front engine cover upwards vertically, otherwise the retaining lugs can break off.

 Installation: Ignition switched off.

10

Suction off oil from expansion reservoir of power steering

 Hand pump

*210589007100

11

Attach engine hoist and raise engine

AR33.10-P-0100-01RT

 Observe the manufacturer's assembly specifications and safety information.

 Bolt, partition wall reinforcement between wheel well liners to fender

*BA62.30-P-1008-01E

 Engine lifting device

*240589006100

12

Lift vehicle to half height

13.1

Remove fender liner in left and right front fender

Vehicles with 4MATIC.

AR88.10-P-1300RT

13.2

Remove rear section of fender liner in left and right front fenders

Vehicles without 4MATIC.

AR88.10-P-1300RT

14

Remove rpm sensor screw (7) on left and right, take off front left rpm sensor (L6/1) and front right rpm sensor (L6/2) from steering knuckle (11), detach electrical lines of front left rpm sensor (L6/1) and front right rpm sensor (L6/2) as far as suspension strut (23)

 Installation: Replace rpm sensor screw (7).

 Self-locking bolt, front axle rpm sensor to steering knuckle

*BA42.30-P-1001-01I

15

Cut through cable ties (10) on steering knuckle (11), open brake hose bracket (12) and unclip brake hose (13) together with decoupling element

 Installation: Pay attention to installation position.
Use new cable ties (10).
The brake hose must not be installed twisted.

 Pliers

*164589013700

16

Detach clamp (14) from brake caliper (17)

 On both sides of the vehicle.

17

Disconnect electrical connector from brake pad thickness contact sensor

 The brake pad thickness contact sensor is only present on one side of the vehicle.

18

Take off plastic caps (15), remove guide pins (16)

 Guide pin to brake caliper support

*BA42.10-P-1002-10L

19

Take off brake caliper (17), remove brake pads and fasten brake caliper to upper transverse control arm (20) using a cable tie

 Installation: Check brake pads, brake caliper, guide pins, brake pad thickness contact sensor, pistons and dust boots, replace if necessary:
Clean contact surfaces of brake pads on brake caliper.
Do not use sharp-edged or pointed objects to clean contact surface. Install brake pads without lubrication.

Press back piston using pusher tool:



Remove/install brakepads on floating brake caliper

AR42.10-P-0160RT

 Resetting device

*000589524300

20

Unscrew link rod nut (25) and release link rod (22) from suspension strut (23)

 In order to release the link rod (22), it may be necessary to lift the lower control arm with a suitable tool or a suitable fixture, until the screw can be removed from the bore on the suspension strut (23).

 Nut, torsion bar linkage to front suspension strut

*BA32.20-P-1003-02L

21

Undo threaded connection (24) on suspension strut (23) and remove screw

 Installation:
Final torque when vehicle is on measuring platform or at K0 design level.
In order to prevent placing rubber bushing under stress.

 Self-locking nut, shock absorber to wishbone

*BA32.25-P-1002-01H

22

Remove steering knuckle nut (27)

 Self-locking nut, upper ball joint out of upper transverse control arm to steering knuckle

*BA33.20-P-1001-01L

23

Detach steering knuckle (11) from upper transverse control arm (20) using puller (21) and thrust piece

 Puller

*601589043300

 Thrust piece

*140589006300

24

Install guard plates (6) for brake cover plates

 Guard plate

*220589013100

25

Raise vehicle fully

AR00.60-P-1000RT

26

Loosen right underfloor paneling (2) and left underfloor paneling (3) behind the left and right front wheel well until screws (39, 41) on centering plates (38) are accessible

27.1

Detach lower engine compartment lining (1)

Vehicles with gasoline engine.

AR61.20-P-1105RT

27.2

Remove bottom section of soundproofing

Vehicles with diesel engine.

AR94.30-P-5300RT

28

Release and disconnect plug (26) from steering gear

29

Unscrew retaining plate screw (32) and remove retaining plate (31)

 Bolt, retaining plate for oil line to control head

*BA46.20-P-1002-01L

30

Tie oil lines (30) of power steering system to one side

 Drain oil lines (30) and seal with stop plugs. Collect and dispose of hydraulic fluid.

 Record plug

*129589009100

31

Unscrew steering coupling screw (29) and remove steering column (28) from steering coupling (29)

 The steering can be turned up to half a revolution of the steering column (28) if the steering coupling screw (29) is not accessible initially.

 Screw/bolt, steering coupling to steering shaft

*BA46.10-P-1001-01K

32

Lower the vehicle until the driver's door can be opened and the steering wheel is accessible

AR00.60-P-1000RT


When opening it the driver's door must not make contact with the two-post vehicle lift and when working in the vehicle interior,
otherwise paint damage on the driver's door can occur.

33

Mount holding device on steering wheel

 Retainer device

*129589012100

34

Raise vehicle fully

AR00.60-P-1000RT

35

Remove front engine mount screws (33) at left and right front engine mount

 Bolt, front engine mount to front axle carrier

*BA22.10-P-1001-03F

36

Mark position of propeller shaft (35) relative to flange of front axle transmission

 Vehicles with 4MATIC.

37

Remove propeller shaft screws (34) and remove together with shim plates

Model 251 (except 251.021/026/054/056/126/154/156)

AR41.10-P-0070-03GZ

 Installation:
Strictly observe tightening procedure and tightening specification.
Otherwise this may lead to noise development and vibrations.

 Vehicles with 4MATIC.

 Self-locking bolt, propeller shaft to front axle gear

*BA41.10-P-1004-01G

 Retainer wrench

*164589020700

38

Release propeller shaft (35) from front axle differential and loosely fasten to vehicle floor using a cable tie


Propeller shaft (35) must not dangle loosely.
Otherwise the joints could be damaged.

 Vehicles with 4MATIC.

39

Support front axle (5) with suitable lifting device (4) and fasten securely to lifting device (4).

40

Remove centering plates (38); to do this, remove screws (37, 39, 41)

 Installation: Fit screws(37, 39, 41) but do not tighten yet. Insert drifts into centering bores (42) and align front axle (5) and centering plates (38). The front axle carrier is in the correct position when the drifts are aligned vertically in the centering bores (42).
Screw in screws (36, 37, 39, 41).

 Self-locking bolt, front axle carrier (front) to longitudinal member

*BA33.10-P-1001-01L

 Self-locking bolt, front axle carrier at rear to longitudinal member

*BA33.10-P-1002-01L

 Bolt, stiffening plate to longitudinal member

*BA33.10-P-1003-01L

 Bolt, stiffening plate to body

*BA33.10-P-1004-01L

 Drift set

*164589011500

41

Remove front axle carrier screws (36)

 Installation: Fit front axle carrier screws (36) but do not tighten.

42

Carefully lower front axle (5)


Lower carefully,
to avoid damage to lines, cables and parts.



Check

43

Check front axle (5) for damage and replace damaged or worn parts if necessary

44

Install in the reverse order

45

Fill power steering pump and bleed

AR46.30-P-0010RT



Check

46

Check oil level in front axle differential, correct if necessary

 Vehicles with 4MATIC.

 Oil filler screw, front axle transmission

*BA33.30-P-1001-03E

 Filling capacity

*BF33.30-P-1001-03E

Loctite 7063 (400 ml) cleaning spray

*BR00.45-Z-1046-04A

Sealant, Omnifit 100H (50 g)

*BR00.45-Z-1061-01A

47

Perform wheel alignment check

AR40.20-P-0200RT

48

Check headlamp adjustment, correct if necessary



AP82.10-P-8260RT

 Only if suspension components were replaced or if the vehicle level was adjusted.

 Engine mount, engine support (engine side)

Number

Designation

Model 251

BA22.10-P-1001-03F

Bolt, front engine mount to front axle carrier

Nm

53

 Front axle torsion bar

Number

Designation

Model 251

BA32.20-P-1003-02L

Nut, torsion bar linkage to front suspension strut

Stage 1

Nm

100

Stage 2: Loosen

°

180

Stage 3

Nm

120

Stage 4

°

45

 Front axle shock absorber

Number

Designation

Model 251

BA32.25-P-1002-01H

Self-locking nut, shock absorber to wishbone

Nm

265

 Front axle carrier

Number

Designation

Model 251

BA33.10-P-1001-01L

Self-locking bolt, front axle carrier (front) to longitudinal member

M141.5

Stage 1

Nm

130

Stage 2

°

–180

Stage 3

Nm

100

Stage 4

°

45

 Front axle carrier

Number

Designation

Model 251

BA33.10-P-1002-01L

Self-locking bolt, front axle carrier at rear to longitudinal member

M141.5

Stage 1

Nm

130

Stage 2

°

–180

Stage 3

Nm

100

Stage 4

°

90

 Front axle carrier

Number

Designation

Model 251

BA33.10-P-1003-01L

Bolt, stiffening plate to longitudinal member

M10

Nm

61

 Front axle carrier

Number

Designation

Model 251

BA33.10-P-1004-01L

Bolt, stiffening plate to body

M8

Nm

20

 Wheel control, hub

Number

Designation

Model 251

BA33.20-P-1001-01L

Self-locking nut, upper ball joint out of upper transverse control arm to steering knuckle

Stage 1

Nm

20

Stage 2

°

90

 Front axle gear

Number

Designation

MODEL 251

Model 251 left-hand drive vehicle, except code 494

BA33.30-P-1001-03E

Oil filler screw, front axle transmission

Nm

35

35

 Propeller shaft

Number

Designation

Model 251

BA41.10-P-1004-01G

Self-locking bolt, propeller shaft to front axle gear

Stage 1

Nm

40

Stage 2

°

90

 Front axle brake caliper

Number

Designation

Model 251 (except 251.077/177)

Model 251.077/177

BA42.10-P-1002-10L

Guide pin to brake caliper support

Nm

55

30

 Front axle rpm sensor

Number

Designation

Model 251

BA42.30-P-1001-01I

Self-locking bolt, front axle rpm sensor to steering knuckle

Nm

8

 Steering shaft

Number

Designation

Model 251

BA46.10-P-1001-01K

Screw/bolt, steering coupling to steering shaft

Nm

33

 Steering gear

Number

Designation

Model 251

BA46.20-P-1002-01L

Bolt, retaining plate for oil line to control head

Nm

18

 Crossmember and front reinforcement

Number

Designation

Model 251

BA62.30-P-1008-01E

Bolt, partition wall reinforcement between wheel well liners to fender

Nm

10

 Front axle gear

Number

Designation

Model 251

BF33.30-P-1001-03E

Filling capacity

Front axle gear

Liter

1,1

Sheet

BB00.40-P-0235-07A

Repair materials

Number

Designation

Order number

BR00.45-Z-1046-04A

Loctite 7063 (400 ml) cleaning spray

A 001 986 71 71 09

BR00.45-Z-1061-01A

Sealant, Omnifit 100H (50 g)

A 002 989 23 71