GMC T Series 1994 Repair Manual page 538

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Inspect
• Sealing flanges for bending or damage.
• Rubber grommets and parts on the rocker arm cov­
er for deterioration.
• Oil pan for rock damage or cracks.
• Oil pan baffle for loose fit.
• Drain plug threads for stripping.
O IL PUMP
Disassemble
❖
1. Oil pump cover screws.
2. Oil pump cover.
• Mark the gear teeth so the pump gears can be
installed with the same gear teeth indexed.
3. Drive gear and shaft.
4. Idler gear.
5. Pressure regulator valve retaining pin, valve,
spring, and related parts.
• Note the order of assembly.
Clean
All parts in clean solvent and blow dry with com­
pressed air.
1 ?
Inspect
• Pump body and cover for cracks or other damage.
• Gears for wear.
• Drive gear and shaft for improper fit in the pump
body.
• Inside of the cover for wear that would permit oil to
leak past the ends of the gears. The pump gears,
cover, and body are not serviced separately. If the
parts are damaged or worn, replace the entire oil
pump assembly.
• Pickup screen and pipe for damage to the screen,
pipe or relief grommet.
❖ Assemble
1. Pressure regulator valve and related parts.
2. Idler gear and drive gear with shaft. Align the
marks made during disassembly.
• Prime oil pump by filling cavity with assembly
lubricant.
3. Oil pump cover.
4. Oil pump cover screws.
Tighten
• Screws to 16 N-m (12 lbs. ft.).
Inspect
Oil pump operation. Turn the drive shaft by hand
and check for smooth rotation.
Figure 51— Removing the Rocker Arm Retainers
VALVE TR A IN COMPONENTS
IJJ Clean
A. Parts in solvent. Blow dry with compressed air.
B. Make sure the oil passages in the pushrods are
clear.
Disassemble (Figure 51)
❖
1. Rocker arm retainers (405).
A. Insert a screwdriver into the rocker arm shaft
bore and break off the end of the retainers.
B. Pull the rocker arm retainers out with pliers (fig­
ure 51).
2. Rocker arms from the rocker arm shaft. Mark the
rocker arms so they can be returned to their origi­
nal locations at assembly.
L* Inspect
• Rocker arms and shafts at their mating surfaces.
These surfaces should be smooth and free from
scoring or other damage.
• Rocker arm areas which contact the valve stems
and the sockets which contact the pushrods. These
areas should be smooth and free of damage and
wear.
• Pushrods for bending. Roll the pushrod on a flat
surface to determine if it is bent. Replace if neces­
sary.
• Ends of the pushrods for scoring or roughness.
• Hydraulic lifter guide plates and clamps for dam­
age.
* Assemble
1. Rocker arms to the rocker arm shaft. Used rocker
arms must be returned to their original locations.
Important
• Lubricate the rocker arms with engine oil before
installing.
2. New rocker arm retainers (405).
A. Center the rocker arms on the corresponding
holes in the rocker arm shaft.