Pinion shaft – all-wheel drive
clutch output shaft
Vent for all-wheel drive
clutch oil supply

642_005

Mechanical oil pump

All-wheel drive clutch
input shaft
All Wheel Drive Hydraulic
Pressure Sensor G942

Coolant connection,
supply

9

Haldex Clutch Pump
V181
Double-lipped oil
seal

All Wheel Drive Hydraulic
Temperature Sensor G943

Electrical plug connection

Mechanical powered
oil pump
Pressure relief valve

Final drive/differential vent

All-wheel drive clutch housing

Shaft oil seal

Clutch piston with axial bearing
Multi-plate clutch
Vent for all-wheel drive clutch oil supply
Front final drive housing

642_004

O-rings

Cooling
duct

Gasket
Sump for V181

Cooling channel plate

Coolant connection

Haldex Clutch Pump V181
All-wheel drive clutch input shaft

Differential/non-locking differential

Pinion shaft – all-wheel drive clutch output shaft
Double-lipped oil seal
Pump sump for mechanical powered oil pump

Haldex oil supply

Intake port for mechanical powered oil pump

Axle oil (MTF) supply

A

Front view
Final drive / differential vent
Differential cover

Splined flange shaft, left

Splined flange shaft,
right

Coolant connection,
supply

Coolant connection,
return

A
Cooling channel plate

642_006
10

Oil supplies
Final drive 0D4 has two independent oil supplies with
separate oil chambers: the axle oil supply and the Haldex
oil supply.

Axle oil (MTF) supply
The oil chamber for the axle oil (MTF, Mechanical Transmission Fluid) is located in the front section of the final drive
housing. A double-lipped oil seal defines the boundaries of
this chamber and seals it off from the Haldex oil.

An oil drainage port stops oil flowing to the other side in
the event of a leak. Refer to Fig. 642_007.

Pressure relief valve
All-wheel drive clutch housing

Central shaft housing

Outlet port for pressure relief valve and
vent for pump sump of Haldex Clutch Pump
V181

Vent for all-wheel drive
clutch oil supply

Central shaft

Mechanical powered oil pump
Radial groove:
connects outlet port
to overflow port
Overflow port for pump sump
of Haldex Clutch Pump V181
leading into pump sump for
mechanical pump

Sealing face

Central shaft housing /
all-wheel drive clutch / final drive bolt

Haldex oil supply
Axle oil (MTF) supply
11

Haldex Clutch Pump V181

Filler plug –
Haldex oil

Drain plug – Haldex oil

Haldex oil supply

Oil deterioration

The Haldex oil chamber is located in the rear section of the
final drive housing. The boundaries of the oil chamber are
defined by the all-wheel drive clutch housing. The sealing
face between the all-wheel drive clutch housing and the
front final drive housing is sealed with liquid sealant.

Due to exposure to shear forces and high temperatures, the
Haldex oil is subject to deterioration which affects friction
levels within the all-wheel drive clutch. The friction levels
are calculated values and are stored in the control module.
They can be seen as “programmed values for oil deterioration” in the Measuring values using the VAS Scan Tool.

If the central shaft has to be removed for servicing, it is no
longer possible to guarantee proper sealing between the
all-wheel drive clutch and the front final drive housing due
to the removal of the "central shaft housing / all-wheel
drive clutch / final drive" bolt. In this case, the gasket must
be replaced. Use the liquid sealant specified in the (ETKA)
for this purpose.
The Haldex oil chamber houses the intake chambers or
pump sumps for the mechanical powered oil pump and
Haldex Clutch Pump V181. The sump for the mechanical
powered oil pump is integrated in the front final drive
housing. The sump for the Haldex Clutch Pump V181 is
integrated in the all-wheel drive housing. It is vented from
the overflow port via the round groove which leads to the
vent port and into the front final drive housing. For further
information about the Haldex oil supply, refer to "Hydraulic
diagram" on page 13.

Changing the oil
Follow the instructions given in ElsaPro and on the VAS
Scan Tool for checking and changing the oil in both supplies. Given that the drain, filler and inspection plugs of
both oil supplies are positioned very close to one another,
there is a possibility of error. Using the wrong oil will cause
irreparable damage to the components. If you change the
Haldex oil, the quantity of oil specified in ElsaPro and must
be used. The bottom edge of the Haldex oil filler plug
thread is not a check mark. The programmed values for oil
deterioration (aging) must also be reset using the VAS Scan
Tool. Refer to "Maintenance and change intervals" on page
26.

Final drive / differential vent
Double-lipped oil seal

Front final drive housing

Leak oil drainage port

642_007

Coolant connection, supply

Axle oil drain plug

Axle oil filler and
inspection plug

12

All-wheel drive clutch
Oil supply, lubrication and clutch cooling
The all-wheel drive clutch is supplied by two pumps: a
mechanically driven oil pump and the electrically controlled
Haldex Clutch Pump V181.

The sump for Haldex Clutch Pump V181 is integrated in the
all-wheel drive clutch housing. It is filled by the mechanical
powered pump.

Each pump has its own circuit with its own sump. The sump
for the mechanical powered oil pump is integrated in the
front final drive housing. The all-wheel drive clutch housing
seals off the Haldex oil supply system. Refer to page 12.

The circuit of the mechanical powered pump is continuously
active during vehicle operation. The circuit of the Haldex
Clutch Pump V181 is demand controlled by All Wheel Drive
Control Module J492. In this case, the circuits operate in
parallel.

Pinion shaft spline

Cooling oil for multi-plate clutch

Cooled multi-plate clutch

All-wheel drive clutch housing

Oil supply for the pump sump of
Haldex Clutch Pump V181

Input shaft – all-wheel drive clutch,
driven by propeller shaft via central shaft
Mechanical
powered oil pump
Pressure side of
pump

Pump
intake side

642_008

Intake port for the mechanical
powered oil pump

Axial piston pump with
centrifugal pressure governor

Sump for
Haldex Clutch Pump V181

!
13

Maximum Haldex oil level in
sump of Haldex Clutch Pump
V181

Haldex Clutch Pump V181
(refer to page 21)

Note
To fill the sump for Haldex Clutch Pump V181 after repairs, the removed final drive can be swivelled back as directed in
ElsaPro after refilling the Haldex oil. An alternative is to drive the completed vehicle for approximately 1.2 m (2 km). The VAS
Scan Tool also provides directions regarding this measure. When the vehicle is driven, the mechanical powered oil pump fills
the sump up to the maximum Haldex oil level. Refer to Fig. 642_008.

Mechanically driven oil pump circuit
Cooling oil for multi-plate clutch

Multi-plate clutch

Mechanical powered oil
pump

All-wheel drive clutch
input shaft

All Wheel Drive Hydraulic
Temperature Sensor G943

642_009

Cooling oil flow and oil supply for V181 sump
Pump sump

Sump for Haldex Clutch Pump
V181
Sump for mechanical powered
oil pump

Mechanically driven oil pump
The mechanically driven oil pump is an internal gear pump.
The pump starts to run when the vehicle begins to roll
forwards.
The inner rotor of the pump interlocks with the all-wheel
drive clutch input shaft. The all-wheel drive clutch input
shaft is driven by the central shaft via the propeller shaft,
the drive shaft and the output shaft of the transmission.
Refer to page 3.

Cooling is essential due to the frictional heat produced by
zero-backlash operation of the clutch. Refer to page 9.
During initial operation of the final drive or if repair work
is needed, it is important to make sure that the sump for
the Haldex Clutch Pump V181 is filled. Refer to note on
page 13.

The task of the oil pump is to fill the sump for the Haldex
Clutch Pump V181, as well as ensuring that the components are lubricated and supplying the multi-plate clutch
with cooling oil.

All Wheel Drive Hydraulic Temperature Sensor G943
For further information refer to page 20.

14

Clutch control
If Haldex Clutch Pump V181 is activated by the control
module, oil from its sump is supplied to the clutch piston
pressure chamber.

Zero-backlash operation of the clutch permits short reaction times during pressure build-up and, therefore, also
during transmission of the desired amount of clutch
torque. This ensures excellent driving dynamics.

Clutch piston with axial bearing

Multi-plate clutch

Pressure chamber

All-wheel drive clutch housing

Outlet port for pressure relief valve
and vent port for
sump of Haldex Clutch Pump
V181
Pressure relief valve, opens at pressures
greater than 638 psi (44 bar)

642_010

Pressure side
of pump

Axial piston pump with
centrifugal pressure governor
Diaphragm spring in clutch
piston pressure chamber

15

Sump for Haldex Clutch Pump
V181, pump intake side

Maximum Haldex oil level in
sump of Haldex Clutch Pump
V181

Haldex Clutch Pump V181

Circuit of Haldex Clutch Pump V181
Pressure chamber
Haldex Clutch Pump
V181

Clutch piston

Multi-plate clutch

All Wheel Drive Hydraulic
Pressure Sensor G942

Pressure relief valve

P greater than 638 psi (44 bar)

642_011

Hydraulic operating pressure
Outlet port

Sump for Haldex Clutch Pump V181

Pump sump / depressurized
Intake line / vacuum

Centrifugal pressure governor
Pump motor

Axial piston pump

Haldex Clutch Pump V181

Venting the pressure chamber:

V181 produces hydraulic pressure in the all-wheel drive
clutch. It consists of a pump motor and the axial piston
pump with centrifugal pressure governor. The hydraulic
pressure in the clutch piston pressure chamber is regulated
by the centrifugal pressure governor based on the speed of
the pump motor. The pump motor is controlled by All
Wheel Drive Control Module J492.

During initial operation of the final drive or if repair work is
needed, it is important to make sure that the sump for the
Haldex Clutch Pump V181 is filled. Refer to note on page
13. This prevents the pump from running dry. The clutch
piston pressure chamber then needs to be vented using the
"ventilation and hydraulic leak test" Test Plan using the VAS
Scan Tool. Refer to page 25. This function allows V181 to
build up a pressure of over 638 psi (44 bar) and vents the
air in the pressure chamber through the pressure relief
valve. Pump operation is clearly audible because the pump
runs at maximum load during the ventilation phase.

The functional principle of V181 is identical to that of the
fifth-generation Haldex clutch.
The circuit of the Haldex Clutch Pump V181 is highlighted
in grey in Fig. 642_011.
All Wheel Drive Hydraulic Pressure Sensor G492
The pressure sensor measures the hydraulic pressure for
the clutch piston and thus monitors the capacity of V181
indirectly. If the pump runs dry, it has no pumping capacity
and is shut down for its protection. Refer to page 20.

16

Cooling
Cooling circuit

8

10

11

9
6

5

7

4

3

2

Coolant circuit for cooling the final
drive during the warm-up phase

1

Heat exchanger
Heater
return line

1 Heater supply line
2 Heat exchanger
3 Flow restrictor
4 Cooling duct plate
5 T piece
6 Coolant thermostat for engine oil cooler
7 Bypass
8 Left hand auxiliary radiator for engine oil cooling (air to water)
9 Engine oil cooler 2 (water to oil)
10 After-Run Coolant Pump V51
11 Coolant thermostat
Heater supply line

From heater

Cooling channel plate
17

To ensure that the all-wheel drive is fully functional in all
driving situations and to counteract oil deterioration (refer
to page 12), the frictional heat of the multi-plate clutch
is dissipated through the cooling oil made available by the
mechanically driven oil pump.
The cooling oil flows through the multi-plate clutch (refer
to page 13, Fig. 642_008) and is discharged into the
sump for the mechanical powered oil pump.

The cooling circuit on page 17 shows the path of the
coolant for cooling the final drive directly after engine
starting. Upwards of a temperature of 203 °F (95 °C) , the
coolant thermostat for the engine oil cooler (6 on previous
page) directs the coolant via the left hand auxiliary radiator
for engine oil and engine oil cooler 2. In this case, coolant
does not flow through the bypass branching off from
coolant thermostat of the engine oil cooler.

To cool the Haldex oil in the sump, coolant flows through
the cooling duct plate from the return line of the heater
circuit. The axle oil (MTF) supply is cooled in addition to the
Haldex oil supply. A flow restrictor within the circuit
ensures that sufficient coolant is diverted.

Bypass

Left hand auxiliary radiator for
engine oil cooling (air to water)

To coolant thermostat
for engine oil cooler