Buick LeSabre 1965 Service Manual page 37

ENGINE
ENGINE DESCRIPTION 2 - 1 5
Figure 2-10—Oil Filter Installation
pressure is relieved on the check
ball at the end of each cycle of
operation.
It should be noted that during
each cycle of operation the verti-
cal movement between the body
and plunger is only .002" to .003"
but the check ball moves through
its full travel of .004" to .008".
Full opening of the plunger feed
hole at the end of each cycle not
only permits replacement of oil
lost from the lower chamber, as
previously described, but also
permits control of the volume of
oil in lower chamber to compen-
sate for expansion and contraction
of the valve linkage parts due to
changes in engine temperature.
When e n g i n e temperature in-
creases and the valve linkage
parts expand, the plunger must
move to a slightly lower position
in the lifter body to assure full
closing of the engine valve. When
engine temperature decreases and
the linkage parts contract, the
plunger must move to a slightly
higher position in body to prevent
lash clearances in the valve link-
age. In either case, the capacity
of the lower chamber changes and
the volume of oil present is auto-
matically controlled by passage of
oil through the open plunger feed
hole.
2 - 6 ENGINE LUBRICATION
SYSTEM
oil is supplied under full pressure
to crankshaft, connecting rods,
and camshaft bearings, and is
supplied under controlled volume
to the valve lifters, rocker arm
bearings, and push rods. All other
moving parts are lubricated by
gravity flow or splash. See Fig-
ure 2-12.
a. Oil Supply
401 & 425 Engine
The supply of oil is carried in the
lower crankcase (oil pan) which
is filled through filler caps in the
rocker arm covers. The filler
openings are covered by combina-
tion filler and ventilating caps
which contain filtering material
to exclude dust. A removable oil
gauge rod on right side of crank-
case is provided for checking oil
level.
b. Oil Pump
401 & 425 Cu. In. Engine
Oil is picked up and circulated by
the spur-geared oil pump assem-
bly which is mounted on the lower
side of the cylinder crankcase at
the rear end, where it extends
down into the oil sump. The pump
shaft is coupled to the ignition
distributor shaft, which is driven
from the camshaft through spiral
gears. The pump inlet is equipped
with a stationary screen of ample
area. If the screen should become
clogged for any reason, oil may
be drawn into the pump over the
top edge of the screen, which is
held slightly clear of the screen
housing by three embossments.
The oil pump body contains a
non - adjustable s p r i n g loaded
pressure valve, which regulates
the maximum oil pressure to 40
pounds.
Drilled passages in the oil pump
body and cylinder crankcase con-
duct all oil from the pump to the
oil filter.
connected by a drilled passage
in the cylinder crankcase to an
oil screen housing and pipe as-
sembly. The screen is submerged
in the oil supply and has ample
area for all operating conditions.
If the s c r e e n should become
clogged for any reason, oil may
be drawn into the system over the
top edge of the screen which is
held clear of the sheet metal
screen housing.
Oil is d r a w n into the pump
through the screen and pipe as-
sembly and a drilled passage in
the crankcase which connects to
drilled passages in the timing
chain cover. All oil is discharged
from the pump to the oil pump
cover assembly. The cover as-
sembly consists of an oil pres-
sure relief valve, an oil filter
by-pass valve and a nipple for
installation of an oil filter. The
spring loaded oil pressure relief
valve limits the oil pressure to
a maximum of 33 pounds per
square inch. The oil filter by-
pass valve opens when the filter
has become clogged to the extent
that 4-1/2 to 5 pounds pressure
difference exists between the fil-
ter inlet and exhaust to by-pass
the oil filter and channel unfil-
tered oil directly to the main oil
galleries of the engine. See Fig-
ure 2-11.
The engine lubrication system is
of the force-feed type in which
The oil pump is located in the
timing chain cover where it is
Figure 2-11—Oil Flow (401 and 425
Cu. In. Engine)