GMC 1989 Light Duty Truck, Repair Manual, Page: 447 / 998

4.3 LITER V-6 6A3-23
0 '
[ 0 0 0 0
>
0 0 0 0 0 0
4 i FRONT
B-07874
Figure 38— Cylinder Head Bolt Tightening Sequence
VALVE TRAIN COMPONENT
INSTALLATION
(Even numbered cylinders are in the right bank; odd
num bered cylinders are in the left bank, when
viewed from the rear of the engine).
3. Back out the adjusting nut until lash is felt at the
pushrod then turn in the adjusting nut until all lash
is removed. This can be determined by rotating the
pushrod while turning the adjusting nut. When the
play has been removed, turn the adjusting nut in
one full additional turn (to center the lifter plunger).
4. Crank the engine one revolution until the tim ing tab
“
0
” mark and torsional dam per mark are again in
alignment. This is the num ber four firing position.
The following valves may be adjusted:
— Exhaust: 2, 3, 4.
— Intake: 4, 5, 6 .
INTAKE MANIFOLD
INSTALLATION
4 4
-
Im portant
Replace all hydraulic lifters if a new camshaft was
installed.
Install or C onnect (Figure 39)
• Lubricate the hydraulic lifter bodies and feet with
Engine Oil Supplem ent (GM Part NO. 1051396 or
equivalent).
1. Hydraulic lifters to the block.
2. Restrictors (46) and retainer (41) with bolts (40).
$
Tig h ten
• Bolts (40) to 16.4 N m (145 in. lbs.).
3. Pushrods.
• Seat the pushrods into the socket in the
hydraulic lifters.
• Coat the mating surfaces of the rocker arms and
balls with “ Molykote” or equivalent.
4. Rocker arms.-
5. Balls.
6
. Nuts.
VALVE ADJUSTMENT
1. Crank the engine until the mark on the torsional
dam per lines up with the “ O ” mark on the timing
tab and the e ngine in the num be r one firin g
position. This may be determined by placing fingers
on the number one valve as the mark on the dam per
comes near the “ O ” mark on the timing tab. If the
rocker arms are not moving, the engine is in the
number one firing position. If the rocker arms move
as the mark comes up to the tim ing tab, the engine
is in the number four firing position and should be
turned over one more time to reach the number one
position.
2. With the engine in the num ber one firing position as
determ ined above, the follow ing valves may be
adjusted:
— Exhaust: 1, 5,
6
.
— Intake; 1, 2, 3.
44
-
44
-
Install or C o nn ect (Figures 40 and 41)
1. Gaskets to the cylinder head with the port blocking
plates facing the rear of the engine.
2. RTV to the front and rear sealing surfaces on the
block. Apply a 5 mm (
3
/ie-inch) bead of RTV (GM
Part No. 1052366 or equivalent) to the front and rear
of the block as shown in figure 40. Extend the bead
13 mm (
1
/
2
-inch) up each cylinder head to seal and
retain the gaskets._
3. Intake manifold to the engine.
4. Intake manifold bolts.
Tig h ten
B o lts to 48 N-m (35 ft. lbs.) u s in g th e
tightening sequence shown in figure 41.
ROCKER ARM COVER
INSTALLATION
44- install or C o nnect (Figure 42)
1. Rocker arm cover and new gasket.
2. Rocker arm cover bolts and washers.
Tig h ten
• Rocker arm cover bolts to 10.2 N-m (90 in.
lbs.).
EXHAUST MANIFOLD
INSTALLATION
Install or C onnect (Figure 43)
1. Exhaust manifold.
2. Heat shield (if removed).
3. Exhaust manifold bolts, washers, and tab washers.
T ighten
• Bolts on center exhaust tube to 36 N-m (26 ft.
lbs.).