GMC C Series 1993 Repair Manual Download

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5D2-2 HYDRAULIC BOOSTER

UNIT REPAIR

BOOSTER ASSEMBLY

Remove or Disconnect (Figures 1 through 5)

Tool Required:

J 26243 Seal Remover

1. Output piston push rod (23) from the front of the

pump.

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N O TIC E : U s in g a th ic k -b la d e w re n c h to

rem ove the flo w sw itch (14) m ay damage the

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sw itch.

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2. Flow switch (14) and O-ring (15),
3. Rubber boot (9) from the back of the pump.

Important

• During disassembly, securely support the bodstef

in a vise by clamping across the mounting flange

(figure 2). The booster position may be changed for

/ the various disassembly operations, but always

clamp across the mounting flange..

! !

4. EH pump bracket bolt arid washer (28).

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NOTICE: The re lie f valve spring (17) and tH^ \ l

re lie f valve stem (16) are very sm all p a rts and !

m ay fa ll o u t o f th e ir bore during the rem oval 0

o f the b o lts (31). Care m ust be used to pro- i

vent the p arts from becom ing lo s t

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5. Bolts and washers (31).
6. EH pump (32).

; 7. O-rings (30).

• 8. Relief valve springs (17).

9. Relief valve stem (16).

• If needed, use a small magnet to take the relief

valve stem (16) and relief valve spring (17) out
of the bore.

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10. Push rod (33) and retainer (34).

A. With the booster clamped in a vise,

large screwdriver in the eye of the

(33). ■

B. Pull straight out to free the push rod.

• Considerable force will be required.

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• An arbor press can be used to provide the

force required.

11. Remove and discard the retainer (34) .fronl the

. push rod (33).

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f; '

• A new retainer must always be used wheri the

push rod is reinstalled. , ,

12. Two of the studs (35) diagonally opposite from

each other (if used). .

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C A U T I O N : T h e p o w e r p i s t o n s p r i n g e x e r t s

c o n s i d e r a b l e f o r c e o n t h e b o o s t e r e n d c o y e i j i

R e m

o v i n g t h e e n d c o v e r r e t a i n i n g s c r e w s

w i t h o u t p r o p e r l y i n s t a l l i n g t h e f u l l y t h r e a d e d

b o l t s w i t h n u t s , c o u l d r e s u l t i n d a m

a g e o r

p e r s o n a l

i n j u r y f r o m

t h e e n d c o v e r a n d

s p r i n g r a p i d l y b e i n g r e l e a s e d f r o m

t h e b o o s t 

e r b o d y .

insert; a

rod

13. InStail 'two 10 mm x 1.5 x 80-mm (3-inch) bolts that

are iftlilly; threaded and, have nuts installed on them,

in opposite corners of the master cylinder mounting

hpjejsj jjfigure 2).

14.  Fingeri tighten  the  bolts  in  the  mounting  hojes.
15.  Fingef tighten  the  nuts  down  to  the  end  cover  (25),
16.  Sdrews! (24)  from  the  end  cover  (25).
17.  Booster  Unit  from  the  vise  and  invert  it  so  the  bolts

ar!e !]resiing against the berich (figure 3).

18. Release the end cover by backing off the nuts on

the bolts in an even sequence.

I 1 i! i, M i ■

;

•;jl;rieispring should push the seal out (figure 3).

•( If j jhe: spring does not push the seal (22) out,

; Ufie'a smooth round-end tool and push in on

the

input push rod assembly side.

19. Two bblts 10 mm x 1.5 x 80 mm (3 inch) with nuts

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-attached.■'

20.  End  cover  (25)  and  piston  rod  seal  (26).
21.  Suppqrt  plate  (27).
22.  Cylinder  seal  (22).
23.  Seal  expander  (21).
24.  Return  spring  (20).
25.  Pistpri  assembly  (19)  and  seal  (18).
26.  Valyei return  spring  (1),
27.  Control  valve  assembly  (2).

> Use !a twisting motion while pulling on the rod.

28. Snul^tjer (bumper) (3).
29. Washer (4) from the counterbore in the booster

bodyl:| i;;

30. V-lip: seal (5) from the booster bpdy,

•| !U;se J 26243 (figure 4).

31. Byppaiss plug (6) and O-ring (7). /

• Form a metal strip into a hook, place it in the

! by pass port, and pull upward (figure 5).

32. Tufie seat (13) along withvO-ring (36).

||jl’se a screw extractor tool to remove the seat.

(mport'ant'

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