Volkswagen Workshop Service and Repair Manuals

Command unit and hydraulic unit - remove and install

Special tools and workshop equipment required

t	"Torque wrench - 5 to 50 Nm (enc. 1/2")" -VAG 1331-

t	Torque wrench - 4 to 20Nm (enc. 3/8") -VAG 1410 -

t	Brake pedal pressing device -VAG 1869/2-

Plug repair set 1H0 698 311 A After disconnecting the command device from the hydraulic unit, always place the valve tube transport protection in the hydraulic unit Hydraulic units without the transport protection are not covered by warranty. 1 -  Valve tube transport protection 2 -  Plugs M 10 3 -  Plugs M 12 Remove Installation location: The command unit is screwed to the hydraulic system unit and is found in the right side of the engine compartment.   WARNING The brake pipes in the hydraulic unit area must not be bent. –  Note the coding in vehicles with code radio equipment, request such coding if necessary. –  Disconnect the battery → Electrical system; Rep. Gr.27. 3 cylinders, injection engine: –  Disconnect the vacuum hoses from the upper air filter case section.

–  Remove the cover by the points marked with -arrows-. 4 cylinders, injection engine: –  Pull the hose from the oil separator and the check valve on the upper air filter case section.

–  Remove the cover by the points marked with-arrows-. 3-cylinder diesel engine: –  Pull the engine cover up and away from the fittings.

–  Remove the intake hose -1-. 4-cylinder diesel engine with injector pump unit: –  Pull the engine cover up and away from the fittings.

–  Remove hose -1- and intake tube -2- → Engine; Rep. Gr.23. or:

–  Remove the flexible aspiration tube-1- and Motor for intake manifold valve -V157--2- → Engine; Rep. Gr.23. 4 cylinders, diesel engine with distribution injector pump: –  Pull the engine cover up and away from the fittings.

–  Remove the escape gas return valve -1-. Continuation for all vehicles:

–  Unlock and disconnect -arrow 1- the connector from command unit -arrow 2-. –  Place the Brake pedal pressing device -VAG 1869/2-. –  Place the ventilation hose of the ventilation reservoir over the left front and left rear brake caliper plugs and open the plugs. –  Press brake pedal at least 60 mm with the Brake pedal pressing device -VAG 1869/2-. –  Close the left front and left rear bleeding plugs. –  Do not remove the Brake pedal pressing device -VAG 1869/2- –  Put an adequate number of lint-free cloths under the command unit and the hydraulic unit. Make sure that no brake fluid reaches the contacts.

–  Unscrew the hydraulic unit pipes -3- connected to the brake cylinder. –  Release the remaining hydraulic unit brake pipes. –  Close the brake pipes and threaded holes with plugs from the repair set number 1H0 698 311 A.

–  Unscrew the hexagonal nuts -1- from the command unit/hydraulic unit. –  Remove the hydraulic unit with the command unit. Install t  Only remove the plugs from the new hydraulic unit when the respective brake pipe is assembled. t  If the plugs were already removed from the hydraulic unit, the brake fluid may leak to the point that proper bleeding and filling can no longer be ensured. When joining the command unit with the hydraulic unit, be careful not to bend the hydraulic unit valve towers with the magnetic coils of the command unit. –  Screw the command unit to the hydraulic unit with the new screws. Make sure that the maximum tightening torque is 4 Nm. –  Screw the ABS unit to the support.

Do not tighten hexagonal nuts completely -2-. This makes screwing each brake pipe -1- to the hydraulic unit easier. Sequence of brake pipes in the hydraulic unit → Chapter –  After screwing the brake pipes, screw the hydraulic unit. –  The rest of the installation process is carried out in reverse order to removal. –  Remove the Brake pedal pressing device -VAG 1869/2-. –  Bleed the brake system → Chapter –  Code ABS control unit -J104-. Connect the Diagnosis, Measurement and Information System -VAS 5051A /52-and select the function → Chapter. –  Code the radio.

Tightening torques:
Command unit in the hydraulic unit	max. 5.5 Nm
Hexagonal head screw to hydraulic unit on the support	8 Nm
Hexagonal nut on the body	20 Nm
Brake pipes in the ABS set:
Threads M 10 x 1	14 Nm
Threads M 12 x 1	14 Nm