1938 LaSalle Production - GM Heritage Center

Cadillac-LaSaile Preliminary Service Information 13
The oil pump drive shaft bearing, the two distributor
drive shafts, aiid their eccentrics for
driving the two fuel pumps are lubricated directly
by passages connected with the main bearing
supply. The timing chain and sprocket are lubricated
by oil which has passed tiirough the front
camshaft bearing.
A pipe leading from the main oil header carries
oil to two small headers along both sides of the
camshaft. Oil from these headers passes to the
hydraulic valve silencers, lubricating them and
providing the pressure necessary for the automatic
valve adjusting action.
The oil filler is in the center of the front valve
chamber cover just behind the generator, and thus
is accessible from either side of the engine. A
float type oil level indicator, reading F (full),
and E (empty) is located at the rear of the
engine vee.
Engine oil recommendations are the same as for
the V-8 engine. Oil should be changed every
2,000 miles, and at this time the carburetor air
cleaners and the crankcase ventilating intake
should be cleaned.
Crankcase Ventilation—The crankcase ventilating
system is of the suction type, similar to that
used on the V-8 engines. The filter-protected
engine oil filler provides the main air inlet. A
pipe for ventilating air also extends from each air
cleaner—one to the front valve chamber, the other
to the rear. Still another pipe extends upward
from the crankcase to the line leading from vacuum
pump to the intake manifolds.
At low speed or part throttle operation, air is
drawn into the crankcase through the oil filler,
and into the valve chambers through the air
cleaner pipes. Cored holes in the crankcase bulkheads
and drilled holes in the valve chamber
walls permit free circulation of air. After absorbing
water and fuel vapors, the air is drawn up through
the vacuum line and into the intake manifolds.
At high speeds, the direction of air circulation
is partly reversed. The manifold vacuum is decreased,
but the rush of air into the carburetors
draws the fumes from crankcase and valve chambers
up through the pipes that lead to the air
cleaners.
Cooling System—Two independent water circulating
systems are used, one for each bank of
cylinders. The radiator bottom tank has two
outlets, each of which is connected to one of the
two centrifugal type water pumps mounted on the
sides of the engine at the front.
The water pumps have several new features.
The impellers are a press fit on the shafts. The
impeller hubs bear against carbon blocks. No lubrication
is required by the pumps.
From each pump, water is forced to the rear
through a tube that extends the full length of the
cylinder, and that sprays water around the valve
chambers and at the same time assures correct distribution
of fluid throughout the blocks. After
circulating in the full-length water jackets, the
water passes upward through regulated openings
into the cylinder heads and then forward to the
outlets.
The cooling system is drained at three points, at
the bottom of each cylinder bank, and at the lower
right side of the radiator core.
Fan, Water Pump and Generator Drive—Two
parallel vee belts driven by double pulleys on the
crankshaft encircle the water pump pulleys at the
sides and the fan pulleys at the top. A novel friction-type
generator drive mechanism permits the
dual belts to drive the fan at slightly less than
engine speed while the generator is being driven
at 1.95 times engine speed.
The dual belts drive a shaft which is supported
by a double row ball bearing. The fan is mounted
directly to the front of this shaft, while at the rear
the shaft carries a drum. The inside of the drum
carries a rubber driving ring against which is
pressed the smaller driving wheel for the generator.
The entire mechanism is supported on a bracket
attached to the front of the engine by two studs.
The hole for one of these studs is slotted to permit
adjustment of the fan belt tension. The generator
end frame is similarly attached to the fan bracket,
and has a slotted hole to permit adjustment of the
friction between the rubber ring and the driving
wheel.
Fig. 10. A double belt arrangement drives fan, generator
and water pumps on the 38-90 engine
The dual belts are adjusted by tightening the
fan bracket until there is no free movement or
looseness in the belts, yet without straining the
belts. This adjustment specification applies to all
38-series belts, and is the same for both new and
used belts.