Hydraulic Control Unit

Fig 1: Hydraulic Control Unit Replacement Components

Courtesy of AUDI OF AMERICA, LLC

1. Bolt
   • 5 Nm
2. All Wheel Drive (AWD) Pump -V415-
   • Removing and installing, refer to PUMP 
3. O-ring
   • Always replace if removed
4. Adapter
   NOTE:

   • The adapter could fall out when removing the AWD pump.
   • Insert the adapter into the recesses in the hydraulic pump before installing the AWD pump.
5. Hydraulic Pump
   • Consists of a guide ring, a housing and 6 pistons
   • Assembling, refer to Fig 2
6. Ball Bearing
   • Can be removed and installed by hand
7. Left Pipe
   • Tighten the nuts to 30 Nm.
   • Installed between the hydraulic control unit and the left chamber
   • First install the nuts hand-tight
8. O-ring
   • Always replace if removed
9. Oil Pressure/Temperature Sensor -G437-
   • 10 Nm
   • Brown connector
   • Removing and installing, refer to OIL PRESSURE/TEMPERATURE SENSOR -G437- OR OIL PRESSURE/TEMPERATURE SENSOR 2 -G640- 
10. Oil Pressure/Temperature Sensor 2 -G640-
    • 10 Nm
    • Black connector
    • Removing and installing, refer to OIL PRESSURE/TEMPERATURE SENSOR -G437- OR OIL PRESSURE/TEMPERATURE SENSOR 2 -G640- 
11. All Wheel Drive (AWD) Clutch Valve 2 -N446-
    • Color: brown
    • Removing and installing, refer to CLUTCH VALVE OR CLUTCH VALVE 2 
    • Installation position: The connector faces upward toward the oil pressure/temperature sensor --
      CAUTION:

      Do not confuse with the AWD clutch valve.

12. All Wheel Drive (AWD) Clutch Valve -N445-
    • Color: black
    • Removing and installing, refer to CLUTCH VALVE OR CLUTCH VALVE 2 
    • Installation position: The connector faces upward toward the oil pressure/temperature sensor --
      CAUTION:

      Do not confuse with the AWD clutch valve 2.

13. Bolt
    • 2.5 Nm
14. O-ring
    • Always replace if removed
    • Position on the clutch valve --
15. Compression Spring
    • Install in the guide, refer to item  16
16. Guide
    • Installation position: The larger diameter faces the ball, refer to item  17
17. Ball
    • Insert into the guide before installing, refer to item  16
18. Hydraulic Control Unit Housing
    • With centering pins -arrows-
    • The centering pins hold the hydraulic control unit and seal to the final drive housing.
19. Ball
    • Insert into the hole in the shuttle valve, refer to item  21 before installing
20. O-ring
    • Always replace if removed
21. Shuttle Valve
    • 8 Nm
    • Removing and installing, refer to Fig 4
22. Gasket
    • With a screen
    • Mount on the centering pins on the hydraulic control unit housing
23. Right Pipe
    • Tighten the nuts to 30 Nm.
    • Installed between the hydraulic control unit and the right chamber
    • First install the nuts hand-tight

Fig 2: Assembling Hydraulic Pump

Courtesy of AUDI OF AMERICA, LLC

-- Insert the 6 pistons -A- into the housing -B-.

-- Position the guide ring -C- so that the piston touches the collar -arrow-.

-- Install the hydraulic pump -1- and the guide ring -2- into the hydraulic control unit housing.

Fig 3: Hydraulic Control Unit Housing

Courtesy of AUDI OF AMERICA, LLC

Functional Check 

-- Turn the hydraulic pump -1- several times. Pay attention to the following when doing this:

• The hydraulic pump must not get stuck or tilt when being turned.
• All the pistons must be pulled out and pushed in.

Fig 4: Identifying Shuttle Valves, Removal/Installation

Courtesy of AUDI OF AMERICA, LLC

-- Remove the shuttle valves -A-. The ball -C- must be removed as well.

-- Insert the ball into the hole in the shuttle valve when installing.

-- Carefully install the shuttle valve with a new O-ring -B- all the way in.

• The shuttle valve must be deeper than the housing surface -arrow-. If this does not happen, then remove the valve again and adjust the position of the ball.

-- Tighten the shuttle valve to the tightening specification, refer to item  21.