Hydraulic Lifters; Cylinder Head; Disassembly - GMC T Series 1994 Repair Manual

• Turn the driveshaft by hand to check for smooth
operation.
N O T IC E : B e c a r e f u l o f tw is tin g , s h e a r in g , o r
c o l la p s i n g t h e p ip e
p u m p .
7. Pickup screen and pipe (187) (if removed) (figure
52).
A. If the pickup screen and pipe assembly was
removed, it should be replaced with a new part.
Loss of press fit condition could result in an air
leak and loss of oil pressure.
B. Mount the .oil pump in a soft jawed vise.
C. Apply sealer to the end of the pipe.
D. Tap the pickup screen and pipe into place,
using J 21882 (5.0L and 5.7L engines), and a
hammer.
E. The pump screen must be parallel with the bot­
tom of the oil pan when installed.
8
. Oil pump driveshaft (178) and connector (179).
VALVE TRAIN COMPONENTS
PUSHRODS, ROCKER ARMS, BALLS, AND NUTS
I j j i Clean
• Parts in solvent. Blow dry with compressed air.
• Make sure the oil passages in the pushrods are
clear.
• Rocker arms and balls at their mating surfaces.
These surfaces should be smooth and free from
scoring or other damage.
• Rocker arm areas that contact the valve stems and
the sockets that contact the pushrods. These areas
should be smooth and free of damage and wear.
• Rocker arm nuts or bolts.
— The 5.0L and 5.7L engines use prevailing
torque nuts. At least 6.2 N-m (55 lbs. in.) of
torque should be required to thread the nuts
onto the rocker arm studs. If not, it is possible
that the nut(s) could back off during engine
operation causing a loss of lash and valve train
noise.
— The 7.4L engine uses a bolt to retain the rocker
arm, ball, and pushrod guide to the cylinder
head. Inspect rocker arm bolts for signs of
cracking at the bolt shoulder. Replace if neces­
sary.
• Check pushrods for bending. Roll the pushrod on a
flat surface to determine if it is bent. Replace if
necessary.
• Check ends of the pushrods for scoring or rough­
ness.

HYDRAULIC LIFTERS

6
Refer to SECTION A.

CYLINDER HEAD

DISASSEMBLY

Disassemble (Figures 53, 54, and 55)
❖
Tool Required:
J 8062 Valve Spring Compressor
1. Valve keepers (251).
w h ile i n s t a l li n g in th e
40. Nut
41. Ball
42. Rocker Arm
46. Cylinder Head
47. Gasket
250. Rocker Arm Stud
251. Valve Keeper
252. O-Ring Seal
253. Cap
254. Rotator
255. Shield
256. Spring
with Damper
257. Seal
258. Exhaust Valve
259. Intake Valve
F9470