Central Hydraulic Pump - Resealing
89audi09
Applies To: 5000, 100/200 1984-89
Subject: Resealing central hydraulic pump
Number: Group:
89-02
November 1, 1989 48
Brakes ^ Steering
Before beginning this procedure, ensure that the hydraulic oil reservoir and strainer are clean. Instructions for cleaning and flushing the hydraulic system can be found in Product Circular No. 88 - 05.
Note
All parts shown marked with an asterisk (*) are included in repair kit, Part No. 026 198 049 B. Use all parts included in the kit when resealing the hydraulic pump.
CAUTION
Part numbers are for reference only. Always check with your Parts Department for latest information.
Hydraulic pump, resealing
Before resealing the hydraulic pump, check the pump pressure.
^ disconnect pressure hose from hydraulic pump (arrow)
^ connect pressure gauge VW 1441 to hydraulic pump at pressure hose port (arrow)
^ start engine and let idle
^ check pressure
^ 145-165 bar (2103-2393 psi)
Note
Do not exceed 10 seconds for the pressure check.
^ replace hydraulic pump if results are not within specifications
^ proceed with pump resealing procedure if results are within specifications
^ remove pump from vehicle
^ mark position of both pump housings with punch (lower arrow)
^ remove bolts (upper arrows), separate pump housings and remove washer
^ remove O-ring (arrow)
^ check for gap between pressure relief valve retainer and pump housing
^ replace pump if gap larger than 0.5 mm (0.019 in.)
^ remove O-rings (arrow)
^ press triangular flange off pump shaft
^ remove pump shaft and bushing from pump housing with plastic mallet
^ check pump shaft/cam and bushing for scoring and uneven wear
^ replace pump if shaft is scored
^ pry seal out of pump housing
CAUTION
Do not scratch inside of pump housing when removing seal.
^ check pump housing (arrow) and bushing at end of housing for damage or uneven wear
^ replace pump if housing is damaged or if scoring is evident in bushing or if bushing is out of round
^ clean pump housings, pump shaft and bushing and air dry
^ press seal in (lettering pointing outward) until seated
^ coat seal between sealing lips with multi-purpose grease
^ lightly oil pump shaft and bushing with hydraulic oil, Part No. G 002 000
^ slide bushing onto pump shaft
^ align washer in pump housing to shaft bore
^ insert pump shaft/bushing into housing while pushing pistons back to allow shaft and bushing to slide into housing at same time
^ press triangular flange on pump shaft (shoulder of flange toward tool) until flush with end of shaft
CAUTION
Coat all O-ring seals with hydraulic oil, Part No. G 002 000, before installing.
^ install new O-ring over pressure relief valve retainer (arrow)
^ install six new O-rings (arrow)
^ slide washer onto pump shaft (arrow)
^ align previously made marks on pump housings
^ install bolts and tighten
^ tightening torque = 35 N-m (26 ft.lb.)
^ modify a 3/4 inch, 1/2 inch drive drag link socket (locally obtainable) by grinding 1.0 mm off each side (arrow)
^ mount pump in vise (use jaw covers)
^ loosen piston caps using hand impact driver and modified drag link socket
^ remove caps and seals one at a time and replace cap seals (arrow)
^ quantity: 8
^ tighten caps to 50 N-m (37 ft.lb.)
Note
Damaged caps can be replaced separately using Part No. 026 145 541.
^ remove two check valves for brake hydraulic portion of pump (arrow)
^ replace O-rings on check valves and reinstall in housing
^ tighten check valves to 15 N-m (11 ft.lb.)
^ pour as much hydraulic fluid, Part No. G 002 000, as possible into outlet port A and rear chamber C
^ fill suction chamber B with hydraulic fluid
^ rotate pump manually through four or five complete revolutions while holding thumb over port A
^ continue rotating pump slowly until pressure is felt and fluid is seen being pumped from port C
^ install pump in vehicle
Labor operation 48 98 51 0
Repair: 190 tu
Quality check: 10 tu
Total suggested repair time: 200 tu