Rocker Arm Stud Replacement; Cylinder Head Assembly; Thermostat And Coolant O Utlet - GMC T Series 1994 Repair Manual

ROCKER ARM STUD REPLACEMENT

4-+
Remove or Disconnect
• Rocker arm stud by unscrewing.
+4- Install or Connect
NOTICE: Refer to "Notice" on page 6A4-1.
• Rocker arm stud.
Tighten
• Rocker arm stud to 47 N-m (35 lbs. ft.).

CYLINDER HEAD ASSEMBLY

+ 4 - Install or Connect (Figures 30, 31, and 32)
Tools Required:
J 8062 Valve Spring Compressor
J 23738-A Valve Stem Seal Tester
1. Valves (74 and 76).
A. Lubricate the valve stems with engine oil.
B. Insert the valves (74 and 76) into the proper
valve guides until the face of the valve contacts
the valve seat.
2. Seal (71) (intake valve only).
A. Install the seal (71) over the valve stem.
B. Hold the valve (74) against the valve seat.
C. Push the seal (71) down the valve stem until it
bottoms out against the head.
3. Springs (73) and dampers (72).
4. Shields (69).
5. Cap (68) or rotator (75).
• Compress the valve spring using J 8062 (figure
31), enough so the lower valve stem groove can be
seen clearly.
6. O -ring seal (70) onto the valve stem 's lower
groove, making sure the seal (70) is flat and not
twisted.
A. Apply a small amount of grease to the area of
the upper valve stem groove.
B. Assemble the two valve keepers into the upper
groove using the grease to hold them in place.
C. Release the com pressor tool J 8062, making
sure the valve keepers stay in place.
D. Repeat the preceding steps on the remaining
valves.
1 ?
Inspect
• O-ring seals for leakage (figure 32).
A. Place the suction cup supplied with J 23738-A
over the shield.
B. Connect J 23738-A to the suction cup and
apply a vacuum.
C. Watch the vacuum pump gage: no air should be
able to leak past the seal.
D. If the seal will not hold a vacuum, it may have
been damaged or improperly installed.
E. Repeat the preceding steps on the remaining
valves.
Measure
• Valve spring installed height of each spring as fol­
lows.
1. Use a narrow thin scale. A cutaway scale may
be helpful.
2. From the top of the shim or the bottom of the
spring to the top of the shield.
3. If this measurement exceeds the amount given
in " Specifications," install valve spring seat
shims approximately 1.6 mm (1/16 inch) thick
(between the spring and cylinder head). NEVER
shim the spring so as to give an installed height
under the specified amount.
THERMOSTAT AND
COOLANT O UTLET
<--»[ Remove or Disconnect
1. Bolts.
2. Coolant outlet.
3. Gasket.
4. Thermostat (with rubber O-ring).
Inspect
• Coolant outlet for cracks.