This information is taken from Workshop Manual TSD4200, Section G6.
We advise only undertaking work on the hydraulic system if you have read and can refer to TSD4200.
Before commencing any operations on the hydraulic/brake pumps the car wings should be suitably protected with wing covers.
Renew: Brake pump housing sealing rings
If brake fluid leakage occurs from the brake pump housing it is possible to renew the two sealing rings with the pump in position using the following procedure.
Depressurise the hydraulic systems as described in Section G2 in TSD4200
Ensure that the pump and the surrounding area are thoroughly clean
Compress the hydraulic pump's low-pressure inlet pipe's rubber hose section to prevent fluid flow. Remove the hose at the centre connection worm-drive clip. Suitably blank the hose end or allow the fluid to drain into a clean container
Note: When work is being carried out on the rear hydraulic pump the ignition distributor should be removed as described in Chapter M of TSD4200. On cars fitted with an exhaust emission control system the three-way connector and check valve must be removed from above the front hydraulic pump (see Section U2 in TSD4200)
Disconnect the hydraulic pump's high-pressure outlet and low-pressure inlet pipes
Remove the circlip from the top of the pump and draw the outer housing upwards and off the pump
Discard the two old sealing rings; fit new ones lubricated with clean brake fluid of the approved type
Fit the pump outer housing, aligning the port with the inlet pipe. Press the housing firmly into position then fit the circlip
Prime the pump with approved brake fluid, connect the low-pressure feed and high-pressure outlet pipes to the pump, and connect the low-pressure hose from the reservoir
Top up the reservoir with approved fluid (see Chapter D in TSD4200) and bleed the hydraulic systems as described in Section G4 in TSD4200
Remove: Brake pump
Carry out Operations 1 to 5, including Hydraulic pump housing sealing rings - To renew.
Using a special box spanner (RH8428), unscrew and remove the pump from its pedestal on the tappet chest cover, and blank off the pedestal against the ingress of dirt
Note: The pump cannot be removed using the top adapter as a spannering point.
Fit and Set: Brake pump
Before fitting the pump to the engine tappet cover flange, ensure that the shim washer fitted between the pump mounting flange and tappet cover is of the correct thickness. For checking, the procedure refer to Chapter E Engine in TSD4200.
To fit the hydraulic pump, reverse the procedure for removal noting the following points.
1The hydraulic pump and pipe connections should be torque tightened in accordance with the figures quoted in Chapter P in the Workshop Manual (TSD4200). The pump should only be tightened using a special box spanner (RH8428), the top adapter should never be used as a spannering point
Bleed the hydraulic systems as described in Section G4. Check all disturbed pipe connections for leaks
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BRAKE PUMP (3/4" union on high pressure brake pipe) (UE40534HBSXR) US$260.61 US$312.73 
