Locating Noisy Lifters; Removal; Installation; Valve Stem Oil Seal And/Or Valve Spring - Chevrolet Light Duty Truck 1973 Service Manual

Fig. 6L—Valve Adjustment
The lifters are extremely simple in design. Readjust­
ments are not necessary, and servicing of the lifters
requires only that care and cleanliness be exercised in
the handling of parts.

Locating Noisy Lifters

Locate a noisy valve lifter by using a piece of garden
hose approximately four feet in length. Place one end of
the hose near the end of each intake and exhaust valve
with the other end of the hose to the ear. In this manner,
the sound is localized making it easy to determine which
lifter is at fault.
Another method is to place a finger on the face of the
valve spring retainer. If the lifter is not functioning
properly, a distinct shock will be felt when the valve
returns to its seat.
The general types of valve lifter noise are as follows:
1. Hard Rapping Noise — Usually caused by the
plunger becoming tight in the bore of the lifter
body to such an extent that the return spring can no
longer push the plunger back up to working
position. Probable causes are:
a. Excessive varnish or carbon deposit causing
abnormal stickiness.
b. Galling or "pickup" between plunger and bore
of lifter body, usually caused by an abrasive
piece of dirt or metal wedging between plunger
and lifter body.
2. Moderate Rapping Noise — Probable causes are:
a. Excessively high leakdown rate.
b. Leaky check valve seat.
c. Improper adjustment.
3. General Noise Throughout the Valve Train — This
will, in most cases, be caused by either insufficient
oil supply or improper adjustment.
4. Intermittent Clicking — Probable causes are:
a. A microscopic piece of dirt momentarily caught
between ball seat and check valve ball.
b. In rare cases, the ball itself may be out-of-round
or have a flat spot.
c. Improper 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, varnish, carbon, etc. is shown to exist in one unit,
it more than likely exists in all the units, thus it would
only be a matter of time before all lifters caused trouble.

Removal

1. Remove valve mechanism as outlined.
2. Mark distributor housing, with chalk, at number
one and number six cylinder position (plug wire)
then disconnect plug wires at spark plugs and coil
and remove distributor cap and plug wire assembly.
3. Crank engine until distributor rotor points to
number one position, then disconnect distributor
primary lead at coil and remove distributor.
4. Remove push rod covers (discard gaskets).
5. Remove valve lifters.
NOTE: Place valve lifters in a rack so that
they may be reinstalled in the same location.

Installation

1. Install valve lifters.
NOTE: Whenever new valve lifters are being
installed, coat foot of valve lifters with
"Molykote" or its equivalent.
2. Install push rod covers, using new gaskets, and
torque to specifications.
3. Install distributor, positioning rotor to number one
cylinder position, then connect primary lead at coil.
4. Install and adjust valve mechanism as outlined.
5. Adjust ignition timing and carburetor idle speed.

Valve Stem Oil Seal and/or Valve Spring

Replacement
1. Remove rocker arm cover as outlined.
2. Remove spark plug, rocker arm and push rod on
the cylinder(s) to be serviced.
3. Install air line adapter Tool J-23590 to spark plug
port and apply compressed air to hold the valves in
place.
4. Using Tool J-5892 to compress the valve spring,
EN G IN E 6-27
LIGHT DUTY TRUCK SERVICE MANUAL