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6 B-4
1977 PONTIAC SERVICE MANUAL
balance could
fail
and fly apart during subsequent
use, creating an extremely dangerous condition.
The majorty of non
A/C
cars use a fan which has
four blades which are unevenly spaced and have
curled tips to provide minimum noise. A fan
shroud is used to prevent recirculation of air
around the fan on most cars.
POWER FLEX FAN
The five blade variable pitch fan is designed to reduce
1
fan noise and increase cooling capacity. At high rpm, air flow
through the grille is sufficient to maintain adequate engine
cooling and the blades tend to straighten out, reducing the
pitch angle by 50% at 5000 rpm. A t h e blade power flex fan
is used on cars with police or trailer options, and some A/C
applications.
1272
Fig. 66-4 Cross Section of Water Pump (L-4 Typical)
A thermostatically controlled fluid clutch fan is used on
some air conditioned equipped V-8's and operates only when
additional air flow is reauired to reduce radiator coolant
The inlet side of the pump is connected to the right
temperatures. This clutch is of a simple functional design and
radiator tank by a hose. The inlet from the heater core is
is made of lightweight metal filled with silicone oil which is
located above the pump inlet from the radiator.
hermetically sealed. The finned (rear) housing contains a hub
assembly (secured to the housing bearing) which attaches to
FAN
the engine water pump (Fig. 6 ~ r 6 ) . ~ou;'bosses with tapped
holes in the rear face provide for attachment of the engine
The engine fan is used to increase the air flow through
fan. The front surface of the housing has six deep circular
the radiator at all speeds (Fig. 6B-5).
grooves which index with six matching bosses on the rear face
CAUTION: I f a tin blade is bent or damaged in
any way, no attempt should be made to repair and
reuse the damaged part. A bent or damaged fan
assembly shouM always be replaced with a new fan
assembly. It is essential that fan assemblies remain
ill
proper balance and proper balance cannot be
assured once a fan assembly has been bent or
damaged. A fan assembly that is not in proper
THERMOSTATICALLY CONTROLLED
I
FLUID CLUTCH FAN
of a floating clutch. A separator
and front cover with
thermostatic coil control complete the clutch assembly.
Function
NOTE: Testing a clutch fan by holding the small hub
with one hand and rotating the aluminum housing in a
clockwise/counter- clockwise motion will cause the
clutch to freewheel, which is a normal condition when
operated in this manner. This should not be considered
Fig. 6 6 - 5 Engine Fans (Typical)
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