Repair And Testing Of Accessories - Continental Motors GO-300-A Overhaul Manual

SECTION XIII
REPAIR AND TESTING OF ACCESSORIES
13-1. HYDRAULIC VALVE TAPPETS.
13-2. DISASSEMBLY. When lifters are disassembled,
it
is essential that a suitable rack be available for
storage of parts in their original relations. This is
an absolute necessity with regard to parts of hydraulic
units. It is advisable to disassemble these units
immediately before they are to be cleaned and to
carry out disassembly" cleaning, inspection and as-
sembly operations in one continuous process. Use
the following disassembly procedure.
a. Invert lifter, and socket and hydraulic unit will fall
into the palm of the hand. Place body and socket
in rack.
b. Usually hydraulic unit plunger may be removed
from cylinder by pulling outward, while turning in
direction which tends to "wind up" spring under its
head. If plunger appears to be "frozen" in cylinder,
it may be held tightly between oil under it and a ring
of carbon on cylinder wall. To test for this condition
and to release plunger simultaneously, insert a medi-
cal swab stick or similar hard wood dowel into open
end of inlet tube, and depress ball check valve. This
will release oil from cylinder, and plunger may be
depressed, unless it is actually stuck to cylinder. A
ring of carbon may be disintegrated and plunger may
be removed by both turning and pulling outward in an
oscillating fashion, while gripping plunger head with
tape-covered pliers.
13-3. CLEANING. All parts of each lifter assembly
should be degreased thoroughly by dipping and brushing
in clean, approved solvent in a small cake pan,
or similar container, which can be placed near the
parts rack on a well-lighted bench. All traces of
dirt must be removed. Extreme care must be exer-
cised to avoid interchanging parts of the assemblies.
Cleaning procedure should be carriedoutimmediately
prior to inspection and testing to avoid an additional
cleaning and preserving operation. Parts and as-
semblies must not stand for more than a few minutes
without application of a corrosion-preventive coating.
13-4. INSPECTION AND TESTING.
a. Inspect face of cam follower on body for any types
of damage. Inspect body bearing surface for scoring
and corrosion. Discard any lifter body which exhibits
any of these faults.
b. Inspect pushrod socket for excessive wear and
roughness in spherical cavity. Wear is indicated by
a polished area at bottom of cavity with a sharp
boundary. Diameter of worn area and its apparent
depth below original, smooth contour give a visual
indication of extent of wear; however, appearance is
usually deceptive, hence a socket should not be dis-
carded unless there is some evidence of penetration of
the hardened surface layer, or unless unit produces an
excessive "dry" lash wherever it is installed in an
engine.
c. Check roughly for diametrical clearance and check
valve wear in hydraulic unit by starting dry plunger into
dry cylinder, then pushing in and releasing it quickly.
For this test, hold cylinder between thumh and middle
finger, and depress piston with index finger. Com-
pression of air in cylinder should make plunger
kick back instantly.
If
piston does not return fully
either it is excessively worn, or check valve is
leaking. To check for a leaking valve, repeat
compression test while plugging end of oil inlet
tube with other hand. If plunger still does not
kick back promptly, it and cylinder are excessively
worn.
If it
does kick back on second test, either
check valve seat is worn and leaking or dirty. In
this event, clean cylinder again, and repeat first
test (tube open).
If
plunger still does not kick back,
the valve is defective. Any unit which fails to pass
this rough test must be discarded. Discard both
cylinder and piston, since these parts are selectively
fitted and are not interchangeable.
13-5 REPLACEMENT. Hydraulic unit (piston, spring
and cylinder) may be replaced as assemblies in any
valve lifter. Parts of these units are selectively fitted
at factory to produce desired leakdown rate, and must
never be interchanged. Lifter bodies may be replaced
independently of hydraulic units,
if
original parts
were damaged. New bodies may be installed in any
engine guide with new or original hydraulic units in
them. Sockets may be replaced independently of
other parts. In order to meet these reqUirements,
lifter parts and units should be kept in their num-
bered positions in parts rack excepting those which
were discarded. Place new parts in vacant spaces of
rack to make up a complete set of lifters.
13-6. ASSEMBLY.
a. Clean all parts with dry-cleaning solvent and drain
dry immediately before starting assembly work.
b. Lubricate interior and exterior surfaces of cylin-
der and surface of piston and spring with only a film
of engine lubricating oil and corrosion-preventive
mixture. Do not lay parts down after lubricating.
Start piston into cylinder and twist to wind up spring
while pushing inward until spring snaps into cyUnder
counterbore.
c. See that valve lifter body is protected with only
a film of engine lubricating oil and corrosion-pre-
ventive mixture inside and out. Insert hydraulic
unit, tube first, against body inner shoulder.
d. Place socket, grooved flat side inward, on piston.
e. When all valve lifters have been assembled in this
manner and replaced in their correct positions in the
parts rack, cover them to exclude dust and grit until
ready to install in engine.
13-7. HARRISON OIL COOLER.
13-8. CLEANING.
a. Soak the assembly in a
tank
of mineral spirit
solvent or cleaners' naptha to loosen a.nd wash out
53