GMC 1989 Light Duty Truck, Repair Manual, Page: 483 / 998

4.8 LITER L6 6A4-29
CYLINDER HEAD
INSTALLATION
JJJ* C lean (Figures 4 and 5)
— Gasket surfaces on the block (115) and cylinder
head (26).
— Threads for cylinder head bolts in the block (115).
Install or C o nn ect (Fig ures 4, 5 and 58)
1. Head gasket (33).
• On engines using a STEEL gasket, coat both
sides of a new gasket with a good sealer.
Spread the sealer thin and even. One method
of applying the sealer that will assure the
proper coat is with the use of a paint roller. Too
much sealer may hold the gasket away from
the head or block.
U se no s e a le r on e n g in e s u s in g a
composition STEEL ASBESTOS gasket.
• Place the gasket in position over the dowel
pins with the bead up.
2. Cylinder head (26). Carefully guide the cylinder
head into place over the dowel pins and head
gasket (33).
3. Bolts (21) and stud (59).
• Coat the threads of the cylinder head bolts
and stud with sealing compound (Loctite #592
or equivalent).
• Install finger tight.
$
Tighten
Bolts (21) and stud (59) a little at a time, using
the sequence shown in figure 58. The proper
torques are as follows:
— Left-hand front bolt 115 N m (85 ft. lbs.).
— All others: 130 N m (95 ft. lbs.).
Figure 59— Timing Marks (Typical)
VALVE TRAIN
COMPONENT INSTALLATION
Im portant
Replace all hydraulic lifters if a new cam shaft was
installed.
Install or C o nn ect (Fig ures 4 and 5)
• Lubricate the hydraulic lifters (100) with Engine Oil
S u p p le m e n t (GM p a rt n u m b e r 105 13 96 ) o r
equivalent.
1. Hydraulic lifters (100) into their mating bores in the
block (115).
2. Pushrods (20). Seat the pushrods into the socket in
the lifters (100).
• Coat the mating surfaces of the rocker arms (13)
and balls (12) with a m olybdenum disulfide grease.
3. Rocker arms (13).
4. Balls (12).
5. Nuts (11).
VALVE ADJUSTMENT
Adjust the valves when in contact with the cam base
circle, as follows:
1. Turn the crankshaft until the tim ing mark on the
vibration dam per is lined up with the “ 0 ” mark on
the tim ing marker (figure 59) and cam lobes #7 and
#9 (counted from the front of the engine) are up.
2. Turn the adjusting nuts for rocker arm numbers 4, 6,
8, 10, 11, and 12 (counted from the front of the
engine) until there is no free lash at the pushrod
(figure 60). Then tighten the nut one full additional
turn (to center the lifter plunger).
3. Crank the engine one full turn (360 degrees) until
the dam per tim ing mark and the “ 0 ” mark on the
tim ing marker are again in alignment. Cam lobes #4
and #6 are now up.
4. Adjust rocker arm numbers 1, 2, 3, 5, 7, and 9 as
outlined in step 2 above.
B-05259