Valve Adjustment; Intake Manifold Installation; Rocker Arm Cover Installation - GMC 1989 Light Duty Truck Repair Manual

VALVE ADJUSTMENT

1. Crank the engine until the mark on the torsional
damper lines up with the " O " mark on the timing
tab and the eng in e in the num ber one firin g
position. This may be determined by placing fingers
on the number one valve as the mark on the damper
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 timing 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 number one firing position as
determ ined above, the following valves may be
adjusted:
— Exhaust: 1, 2, 3
— Intake: 1, 5, 6
(Even numbered cylinders are in the left bank; odd
numbered cylinders are in the right bank, when
viewed from the rear of the engine).
3. Back out the adjusting nut until lash if 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 (figure 41).
W hen th e p la y has been rem ove d, tu rn the
adjusting nut in one and one-half additional turns (to
center the lifter plunger).
4. Crank the engine one revolution until the timing tab
" O " mark and vibration dam per mark are again in
alignment. This is the number four firing position.
The following valves may be adjusted:
— Exhaust: 4, 5, 6
— Intake: 2, 3, 4
2.8 LITER V-6 6A2-25
INTAKE MANIFOLD
INSTALLATION
+ +
Install o r C onn ect (F igure 42)
1. RTV to the front and rear sealing surfaces on the
block. Apply a 5 mm (3/ie-inch) bead of RTV (part
number 1052917 or equivalent) to the front and rear
of the block as shown.
• Make sure that no oil or water is present on
the surfaces to be sealed.
2. Gaskets to the cylinder head.
• Gaskets are marked Right Side or Left Side and
" This Side Up" . Use them only as indicated to
maintain design efficiency of the engine.
• Hold the gaskets in place by extending the
bead of RTV 6 mm (1 /4-inch) from the block
sealing surfaces up onto the gasket ends.
• The new gaskets will have to be cut where
indicated to install beh in d'th e pushrods. Cut
only the areas where necessary.
3. Intake manifold.
• Make sure the areas between the case ridges
and the intake manifold are completely sealed.
4. Intake manifold bolts and nuts.
$ Tighten
Nuts and bolts to 21 N-m (15 ft. lbs.) in the
sequence shown in figure 42. Then re-torque in
the same sequence.
ROCKER ARM COVER
INSTALLATION
Clean
• All traces of old gasket from the rocker arm cover
and cylinder head.
Inspect
• Rocker arm cover sealing surfaces for distortion.
Replace if necessary.
Install or C onnect (Figure 43)
1. Rocker arm cover and gasket.
• Apply a 5 mm (3/ie-inch) dab of RTV sealant
(GM Part No. 1052917 or equivalent) at the
point where the inlet manifold meets the head.
2. Rocker arm cover nuts and reinforcements.
Tighten
• Nuts to 8 N-m (6 ft. lbs.).