Chevrolet 70 1969 Series, Shop Manual

Page: 316 / 913

SECTION 6K
ENGINE COOLING SYSTEM
Cooling system in all models is of the pres­
sure type. A pressure relief valve, either separate
or integral with the radiator or surge tank filler
cap, maintains a pressure of nine pounds in cool­
ing system.
COOLANT CIRCULATION
V-6 G A S O L IN E ENG IN ES
The water pump, belt driven from engine
crankshaft pulley, circulates the coolant through
the cooling system. The coolant from radiator (and
surge tank - when used) is forced into front of
each cylinder bank (fig. 1) where it traverses
around the cylinders to rear of each bank. From
here it flows upward through transfer holes and
into rear of cylinder heads, then back to front of
heads. At this point a portion of coolant flows up
and out of the engine water manifold and back to
radiator. The remaining portion of coolant is re­
circulated back into water pump and engine.
Two thermostats are used in V-6 Gasoline
Engines. Thermostats are installed in top of engine
water manifold.
Engine Warm-Up Period
During engine warm-up period, the thermostat
valves are closed and shut off circulation to the
radiator. As the engine warm s up, the valves open
slowly, allowing a gradually increasing amount of
Figure J — Coolant Circulation (V-6 Gasoline Engine)
CHEVROLET SERIES 70-80 H EAVY DUTY TRUCK SH O P M A N U A L