Chevrolet 1977 light duty truck, Service Manual

Page: 495 / 861

with each service kit. Install seal following
procedures outlined on the supplied instruction
sheet.
2.
Set the valve spring and d a m p e r and valve cap
in place.
3. Com press the spring with Tool J-5892 and
install the valve locks then release the compressor tool,
m ak in g sure the locks seat properly in the groove o f the
valve stem.
N O T E : G rease may be used to hold the locks in
place while releasing the compressor tool.
4. Install spark plug an d torque to specifications.
5.
Install and adjust valve m echanism as previously
outlined.
VALVE LIFTERS
H ydraulic valve lifters very seldom require a tte n ­
tion. The lifters are extremely simple in design,
readjustm ents are not necessary, and servicing o f the
lifters requires only th at care and cleanliness be
exercised in the handling o f parts.
Locating Noisy Lifters
Locate a noisy valve lifter by using a piece o f
g a rd e n hose approxim ately four feet in length. Place one
end o f the hose n ear the end o f each intake and exhaust
valve with the other end o f the hose to the ear. In this
m an n er, the sound is localized making it easy to
determ in e which lifter is at fault.
A n o th e r m ethod is to place a finger on the face o f
the valve spring retainer. If the lifter is not functioning
properly, a distinct shock will be felt w hen the valve
returns to its seat.
T h e general types o f valve lifter noise are as
follows:
1. Hard R ap p in g N o is e - U s u a lly caused by the
plunger becom ing tight in the bore o f the lifter body to
such an extent that the retu rn spring can no longer push
the plunger back up to w orking position. Probable causes
are:
a. Excessive varnish or carbon deposit causing
a b n o rm a l stickiness.
b. G allin g or "p ic k -u p " between plu nger and
bore o f lifter body, usually caused by an abrasive piece
o f dirt or metal w edging between plunger and lifter
body.
2.
M oderate R a p p in g N oise-Probable causes are:
a. Excessively high leakdown rate.
b. Leaky check valve seat.
c. Im p ro p er adjustm ent.
3. G e n e ra l Noise T h ro u g h o u t the Valve T rain-This
will, in most cases, be caused by either insufficient oil
supply or im p ro p e r adjustm ent.
4. Interm ittent Clicking-Probable causes are:
a. A microscopic piece o f dirt m om entarily
caught between ball seat an d check valve ball.
b. In rare cases, the ball itself m ay be out-of-
ro und o r have a flat spot.
c. Im p ro p e r adjustment.
In most cases where noise exists in one or more
lifters all lifter units should be removed, disassembled,
cleaned in a solvent, reassembled, and reinstalled in the
engine. If dirt, corrosion, carbon, etc. is shown to exist in
one unit, it more likely exists in all the units, thus it
would only be a m atter o f time before all lifters caused
trouble.
Removal
1. Remove intake m anifold as previously outlined.
2. R em ove valve m ec h a n ism as previously
outlined.
3. Remove valve lifters.
NOTE: Place valve lifters in a rack so that they
m ay be reinstalled in the same location.
Installation
1. Install valve lifters.
NOTE: W henever new valve lifters are being
installed, coat foot o f valve lifters with "M o ly k o te"
or its equivalent.
2. Install intake m anifold as previously outlined.
3. Install and adjust valve m echanism as outlined.
Disassembly
1. Hold the plunger down with a push rod, and
using the blade o f a small screw driver, remove the push
rod seat retainer.
2. Remove the push rod seat and m etering valve
(fig. 6A-17V).
3. Remove the plunger, ball check valve assembly
and the plunger spring.
4. Remove the ball check valve and spring by
I. L ifte r B o d y
2 Push Rod S e a t
3. M e te rin g V a lv e
4 C h e c k B a ll
5 C h e c k B a ll R e ta in e r
6 Push Rod S e at
R e ta in e r
7 P lu n g e r
8 C h e c k B a ll S p rin g
9 P lu n g e r S p rin g