Buick LeSabre 1965 Service Manual page 39

ENGINE
ENGINE DESCRIPTION 2 - 1 7
GEAR
IL PUMP
COVER
Figure 2 - 1 3 — O i l Flow
(300 C u . In. Engine)
it is then transferred to the
timing chain.
Valve Lifters and Oil Galleries.
Oil holes in the crankcase and
camshaft front bearing align with
a groove in the camshaft front
bearing journal which meters the
flow of oil from the main oil
gallery to the valve lifter oil gal-
lery in each bank of cylinders.
The drilled oil gallery, running
full length of each cylinder bank,
cuts into the lower sides of all
valve lifter guide holes to supply
an adequate volume of low pres-
sure oil to each hydraulic valve
lifter. Oil enters each l i f t e r
through grooves and holes in the
lifter body and the plunger. See
Figure 2-12.
Rocker Arms, Valves, and Push
Rods. The r o c k e r arms and
valves on each cylinder head are
supplied with low pressure oil
from the valve lifter oil gallery
through c o n n e c t i n g passages
drilled in the front end of cylinder
block and head. See Figure 2-12.
The oil passage in cylinder head
ends in a counterbored recess
s u r r o u n d i n g the bolt which
attaches the rocker arm shaft
front bracket. The oversize bolt
hole through the bracket permits
oil to flow up into the hollow
r o c k e r arm shaft, which is
plugged at both ends.
Each rocker arm receives oil
through a hole in the shaft, and
parallel grooves in the rocker
arm assure proper lubrication of
the bearing surface. Oil.is me-
te red to the push rod ball seat and
to the valve stem through holes
drilled in the rocker arm. Excess
oil drains off and returns to the
oil pan through passages in cyl-
inder head and cylinder block.
2 - 7 ENGINE COOLING
SYSTEM
The engine cooling system is the
pressure type, with thermostatic
coolant temperature control and
water pump circulation.
A double contact temperature
sensitive switch is located in the
right cylinder head. On 401 and
425 cu. in. engines, the switch
closes one set of contacts to light
a green signal on the instrument
panel when engine water tempera-
ture is below 110°F. If engine
w a t e r temperature is between
110° and 245° (approximately)
neither contact is closed. Engine
water temperature above 245°
causes the second set of contacts
to close and light a red signal on
the instrument panel.
A Harrison tube and center type
of radiator core of brass and cop-
per is used on all models. The
lower radiator tank houses the
transmission oil cooler.
All engines are equipped with an
18
M
fan. Air conditioned cars are
equipped with a 20" fan driven by
a torque and temperature sensi-
tive clutch. See Figure 2-14.
FAN CLUTCHj
Figure 2-14—Fan Clutch
The torque sensitive fan clutch is
equipped with a temperature sen-
sitive coil which controls the flow
of silicone through the clutch.
During periods of operation when
radiator discharge air tempera-
ture is low, the fan clutch limits
the fan speed to 800 to 1200 RPM.
Operating conditions that produce
high radiator discharge air tem-
peratures cause the temperature
sensitive coil to turn a shaft which
opens a port inside the clutch.
This open port allows a greater
flow of silicone providing a maxi-
mum fan speed of approximately
2100 RPM.
The clutch coil is calibrated so
that at road load with an ambient
temperature of 80°F the clutch is
just at the point of shift between
high and low fan speed.
The cooling system is sealed by a
pressure type radiator filler cap
which causes the system to oper-
ate at higher than atmospheric
pressure. The higher pressure
raises the boiling point of coolant
and increases the cooling effi-
ciency of the radiator. The fifteen
pound pressure cap used on all
series permits a possible in-
crease of approximately 38°F. in
boiling point of coolant.
The pressure type radiator filler
cap contains a blow off or pres-
sure valve and a vacuum or at-
mospheric valve. See F i g u r e
2-15. The pressure valve is held