GMC T Series 1994 Repair Manual page 483

t { | Measure (Figures 60 and 61)
• Valve spring installed height of each valve spring
as follows:
1. Use a narrow, thin scale. A cutaway scale (fig­
ure 60) may be helpful.
2. Measure from the valve shim or spring seat to
the top of the shield (255) (figure 61).
3. If this measurement exceeds the amount given
in " Specifications," install valve spring seat
shim s of sufficient thickness (between the
spring and cylinder head) to give the desired
measurement. NEVER shim the spring so as to
give an installed height under the specified
amount.
ASSEMBLY (7.4L ENGINES)
* Assemble (Figures 54 and 55)
Tool Required:
J 8062 Valve Spring Compressor
1. Valves (258 and 259).
A. Lubricate the valve stems with engine oil.
B. Insert the valve into the proper guide.
2. Rotators (254).
3. Seals (257).
A. Lubricate the seals with engine oil.
B. Push the seals into place.
k
A. Grind out this portion.
Figure 60— Cutaway Scale
4. Valve springs with dampers (256).
5. Caps (253).
6
t f |
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❖
1. Bolts (24) or studs (20).
2
3. Thermostat (23).
L*
B5248
Thermostat Check
Refer to SECTION 6B1 in the appropriate Light Duty
Truck Service Manual.
-► 4-
1. Thermostat (23) with rubber O-ring.
2
3. Bolts (24) or studs (20).
. Valve keepers (251).
A. Compress the valve spring using J 8062 (figure
55). Compress the spring until the valve stem
groove can be seen.
B. Apply a small amount of grease to the area of
the valve stem groove.
C. Assemble the valve keepers, using the grease
to hold the keys in place. Make sure the keep­
ers seat properly in the groove.
D. Release the compressor tools. Make sure the
valve keepers stay in place.
E. Repeat this procedure on the remaining valves.
Measure (Figures 60 and 61)
• Valve spring installed height of each valve spring.
1. Use a narrow, thin scale. A cutaway scale (fig­
ure 60) may be helpful.
2. Measure from the spring seat to the top of the
valve spring (figure 61).
3. If this measurement exceeds the amount given
in " Specifications," install valve spring seat
shims of sufficient thickness (between the
spring and cylinder head) to give the desired
measurement. NEVER shim the spring so as to
give an installed height under the specified
amount.
THERMOSTAT AND COOLANT
OUTLET
Disassemble (Figures 62 and 63)
21
. Coolant outlet ( ).
Inspect
• Coolant outlet for cracks.
install or Connect (Figures 62 and 63)
N O T IC E : D o n o t in s t a ll t h e r m o s t a t a s s e m b ly
w ith o u t r u b b e r O -r in g . O m it t in g r u b b e r O - r in g
m a y r e s u l t in p o o r e n g i n e
r e d u c e d h e a t e r p e r f o r m a n c e .
21
. Coolant outlet ( ).
N O T IC E : R e f e r to " N o t i c e " o n p a g e 6 A 5 -1 .
w a r m - u p a n d