51 24 150 Removing and installing/replacing hydraulic control unit for operating trunk lid (electrohydraulic/fully automatic)

Read information on automatic trunk lid controls (electrohydraulic), refer to 51 24... INFORMATION ON AUTOMATIC TRUNK LID CONTROLS (ELECTROHYDRAULIC)
Remove lid in luggage compartment trim on right, refer to 51 47 172 REMOVING AND INSTALLING/REPLACING FLAP IN LUGGAGE COMPARTMENT TRIM, LEFT OR RIGHT .
Have a cleaning cloth on hand to catch emerging fluid.

Release expansion rivets (1).

Feed out emergency release mechanism (2) for tank cap and remove cover (3).

Remove and install battery.

Fig 1: Removing Emergency Release Mechanism For Tank Cap & Cover

CAUTION: Catch emerging fluid with a cleaning cloth.
Remove hollow union bolts (1) and (2).

Installation:

Hollow union bolt on hydraulic control unit "RED"
Hollow union bolt on hydraulic control unit "BLUE"
Hose marking is "red"
Hose marking is "blue"

Fig 2: Identifying Hydraulic Control Unit

NOTE: If the hydraulic control unit is replaced or remains removed for a longer time, the holes on the hydraulic control unit and the hose connections on the hydraulic cylinder must be plugged.

Sealing connections on hydraulic control unit and hose connections for hydraulic cylinder:

For the hydraulic control unit, use the plugs (1) from the "Hollow union bolts for hydraulic control unit" set (sourcing reference: BMW Parts Service) and the old seals.

For the hose connections, use the plugs with cap nuts (2) from the "Hollow union bolts for hydraulic cylinder" set (sourcing reference: BMW Parts Service) and the old seals.

Fig 3: Identifying Hydraulic Control Unit Plugs & Plugs With Cap Nut

Installation:

Always install new hollow union bolts (1) and seals (2 and 4) (sourcing reference BMW Parts Service).

Hollow screw
Upper seal (thin)
Hose connection
Lower seal (thick)

Fig 4: Installing Hollow Union Bolts & Seals

Disconnect plug connection (1) and release nuts (2). Remove hydraulic control unit (3) and set down on cloth (4).

Installation:

During installation, do not damage PDC control unit.

Fig 5: Removing Hydraulic Control Unit

Disconnect plug connection (1) and withdraw hydraulic control unit (2).

Fig 6: Disconnecting Plug Connection & Withdrawing Hydraulic Control Unit

Only replace:

Release nuts (1) and remove bracket (2) from hydraulic control unit (3).

Unscrew holder (4) for plug connection.

Fig 7: Removing Bracket From Hydraulic Control Unit

Only replace:

If necessary, remove faulty bearings (1) from hydraulic control unit (2) and replace.

Fig 8: Removing Faulty Bearings From Hydraulic Control Unit

Checking fluid level in hydraulic control unit:

Test requirements:

Close trunk lid once and then open again so as to bleed the system.

When the cylinder is fully extended (trunk lid open), the fluid level must be in area (A) of the marking (1) on the hydraulic control unit (2).

Fig 9: Identifying Marking On Hydraulic Control Unit

Topping up fluid in hydraulic control unit:

Release oil filler plug (1) on hydraulic control unit (2). Add as much hydraulic fluid (sourcing reference: BMW Parts Service) until it reaches area of marking.

Fit a new oil filler plug (1) and seal.

Check fluid level again.

Fig 10: Identifying Oil Filler Plug & Hydraulic Control Unit