GMC 1982 Light Duty Truck, Руководство по обслуживанию

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6.2 DIESEL 6A7-11
When the lifter begins to roll up the cam lobe, the
check valve disc is held against its seat in the plunger by the
check valve disc spring which traps the oil in the base of the
lifter body below the plunger. The plunger and lifter body
then raise as a unit, pushing up the push-rod to open the
valve. The force of the valve spring which is exerted on the
plunger through the rocker arm and push-rod causes a slight
amount of leakage between the plunger and lifter body. This
"leak-down" allows a slow escape of trapped oil in the base
of the lifter body. As the lifter rides down the other side of
the cam lobe and reaches the base circle or "valve closed"
position, the plunger spring quickly moves the plunger back
(up) to its original position. This movement causes the check
valve disc to open against the check valve disc spring and oil
from within the plunger is drawn into the base of the lifter.
This restores the lifter to zero lash.
R e m o v a l (6 A 7 -1 8 )
Valve lifters and push rods should be kept in order so
they can be re-installed in their original position. The push
rods must be installed with painted end up. This is necessary
as the premium ball is located on the upper end only.
1. Remove rocker arm covers as previously outlined.
2. Remove rocker arms as previously outlined.
3. Remove guide clamps and guide plates. It may be
necessary to use mechanical fingers to remove the guide
plates.
4. Remove lifters using Tool J-29834 and a m agnet
through access holes in cylinder head.
D issassem bly (Fig. 6 A 7 -1 9 )
1. Remove the retainer ring with a small screwdriver.
2. Remove push-rod seat and oil metering valve.
3. Remove plunger and plunger spring.
4. Rem ove check valve retainer from plunger, then
remove valve and spring.
C le a n in g a n d Insp ection
After lifters are disassem bled, all parts should be
cleaned in clean solvent. A small particle of foreign material
under the check valve will cause malfunctioning of the lifter.
Close inspection should be made for nicks, burrs or scoring
of parts. If either the roller body or plunger is defective,
replace with a new lifter assembly.
Whenever lifters are removed, check as follows:
1. Roller should rotate freely, but without excessive play.
2. Check for missing or broken needle bearing.
3. Roller should be free of pits or roughness. If present,
check cam shaft for sim ilar condition. If pits or
roughness are evident, replace lifter and camshaft.
A ss em b ly
1. Coat all lifter parts with a light coating of clean engine
oil.
2. Assemble valve disc spring and retainer into plunger.
Make sure retainer flange is pressed tight against
bottom of recess in plunger.
3. Install plunger spring over check retainer.
4. Hold plunger with spring up and insert into lifter body.
Hold plunger vertically to prevent cocking spring.
5. Install oil metering valve and push rod seat into lifter
and install retaining ring.
In s ta lla tio n
Prime new lifters by working lifter plunger while
submerged in new kerosene or diesel fuel. Lifter could be
damaged if dry when starting engine.
Coat the roller and bearings of lifter with 1052365
lubricant or equivalent.
1. Install lifters into original position in cylinder block.
Using rigid mechanic’s wire or welding rod. Fabricate a
lifter installing tool.
2. Install valve lifter guide plate.
3. Install guide plate clamp. Crankshaft must be
manually rotated 720° after assembly of lifter guide
plate clamp to insure free movement of lifters in guide
plates.
CRANKSHAFT PULLEY
R e m o v a l
1. Disconnect battery.
2. Remove generator belt.
3. Remove power steering belt.
4. Remove A /C belt if equipped.
5. Remove pulley.
In s ta lla tio n
1. Install pulley.
2. Install belt(s). Adjust belts. See Section 6B.
TO RSIO NAL DAM PER (Fig. 6A7-20)
R e m o v a l
1. Disconnect battery.
2. Remove crank pulley as previously oulnned.
3. Remove torsional damper using tool J-23523 and
suitable pilot or pilot J-29788.
In s ta lla tio n
1. Install damper using a mallet. A ssem ble key parallel to
crankcase. Tap damper far enough on crankshaft so