Hummer H1 Service Manual page 71

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2-34 Engine
Cleaning and Inspection
Clean the valve train components in parts cleaning solvent.
Carb cleaner or a spray type gasket remover can be used to re-
move stubborn deposits.
Mark position of the rocker arms on the shafts. Remove the
rocker arm retainers with pliers. Then remove the arms and ex-
amine the shafts for wear, grooving, or surface cracks. Check
the rocker arms for cracks at the shaft bores and for wear at the
valve and push rod contact points. Replace worn, or damaged
parts as needed.
Check the pushrods for wear, or distortion. Replace any push
rod exhibiting wear (at either end), or if bent, or kinked.
NOTE: The rocker arm end of each pushrod is identified with
a paint stripe. The ball at this end is also coated or heat treated
giving it a distinctive copper color.
Installation
1. Lubricate all parts with engine oil, or with a quality assem-
bly lube.
2. Install pushrods in same sequence as when removed.
Verify that heat treated or coated end is facing up toward
rocker arm.
3. Assemble rocker arms and shaft if necessary. Secure arms
with new retainers but be sure reused arms are installed on
same shafts and in same position. Do not intermix parts.
4. Index crankshaft and pistons for rocker arm shaft
installation as follows:
a. Position breaker bar and socket on crankshaft damper
bolt. Do not use starter to rotate crankshaft. Turn shaft
with hand tools only.
b. Rotate crankshaft counterclockwise, and align mark
on torsional damper with ÒOÓ mark on front cover
timing tab.
c. Rotate engine counterclockwise an additional 3 1/2
inches (89 mm), measured at mark on torsional
damper. Damper mark should align with water pump
first, lower attaching bolt at this point (Figure 2-43).
5. Align and install rocker arm and shaft assemblies
(Figure 2-36). Be very sure pushrods are seated in lifters
and in rocker arms.
6. Install rocker arm shaft retainers and bolts. Tighten bolts
in small increments until snug, with socket and ratchet or
nut runner.
CAUTION: Do not use an air wrench to tighten the bolts. In
addition, stop tightening if the bolts become hard to turn be-
fore they are seated. If this condition occurs, the crankshaft
and pistons are not properly indexed, allowing the valves to
contact the pistons.
7. Verify that pushrods are properly seated in rocker arms
and lifters. Then final-tighten rocker arm shaft bolts to 41
lb-ft (56 N¥m) torque.
8. Install rocker covers and intake manifold as described in
this section.
COATED/TREATED END
PAINT MARK
Figure 2-37: Pushrod I.D.
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