Disassembly; Tools And Shop Equipment; Accessory Removal; Cleaning - GMC 1989 Light Duty Truck Repair Manual

6A4-4 4.8 LITER L6
1
. O il Cap
2
. C lip
3. S crew
4. R e in fo rc e m e n t
5. PCV Valve
6
. Seal
7. R o cke r A rm C over
8 . G a sket
9. G ro m m e t
10 . C o n n e c to r
11
. N ut
12
. Ball
13. R o cke r A rm
14. R o cke r A rm S tud
15. Valve Key
16. O -ring Seal
17. R o ta to r
18. S h ie ld
19. Seal
20 . Valve S p rin g

TOOLS AND SHOP EQUIPMENT

A clean, well lit work area should be available. Other
necessary aids include: A suitable parts cleaning tank,
compressed air supply, trays to keep parts and fasteners
organized, and an adequate set of hand tools.
An approved engine repair stand will aid the work and
help prevent personal in ju ry or dam age to engine
compartments.
Special tools are illustrated throughout this section, and
are listed at its end. These tools (or their equivalents) are
specially designed to quickly and safely accomplish the
operations for which they are intended. The use of these
tools will also m inim ize possible dam age to engine
components.
Some precision m easuring tools are required for
in s p e c tio n of c e rta in c r itic a l c o m p o n e n ts . Torque
wrenches will be necessary for correct assem bly of
various parts.

ACCESSORY REMOVAL

This manual assumes that the engine accessories have
been removed. These accessories may include one or
more of the following:
Hydraulic Pump
Generator
Distributor

DISASSEMBLY

21. P ushrod
22. B o lt
23. B o lt
24. W a sh er
25. B ra cket
26. C y lin d e r Head
27. G asket
28. S tud
29. W a sh er
30. N ut
31. In ta ke M a n ifo ld
32. N ut
33. Head G a sket
34. C lam p
35. B o lt
36. G asket
37. E xh au st M a n ifo ld
38. S tud
39. B o lt
40. W a sh er
Figure 3— Cylinder Head, Manifolds, and Components
AIR Pump
Cooling Fan
Carburetor
52. T h e rm o s ta t
53. G a sket
54. W a te r O u tle t
55. B o lt
56. S tud
57. W a sh e r
58. B ra cket
59. S tud
It is beyond the score of this manual to detail the many
different accessory installations. Refer to the proper Truck
Service Manual for this information.
Diagrams of emission and vacuum hose routings,
wiring harness routings, accessory drive belt layout, etc.,
should be made before removing accessories.

CLEANING

Remove the engine accessories before cleaning to
provide better access to engine exterior surfaces. After
removing the carburetor, distributor, fuel pump, oil filter,
etc., cover the openings with tape to prevent the entry of
water, solvent, and dirt.
Methods used to clean the engine will depend on the
aids w hich are available. Steam cleaning, pressure
w ashing, or solvent cle a n in g are som e accep tab le
methods. Allow the engine to dry before beginning the
work.
It is important that the engine be as clean as possible to
p re v e n t d ir t fro m e n te rin g c r itic a l a re a s d u rin g
disassembly.

PARTS IDENTIFICATION

Refer to figures 3 through
41. S tud
42. In ta ke Valve
43. E xh a u st Valve
44. S w itc h
45. Plug
46. C la m p
47. H ose
48. N ip p le
49. G a sket
50. H o u s in g
51. B o lt
B-07995
6 .