GMC 4000 Series Service Manual page 320

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COOLANT CIRCULATION
IN-LINE GASOLINE ENGINES
The water pump, belt-driven from engine
crankshaft pulley, circulates coolant through the
cooling system . Coolant from the radiator is forced
through engine water jacket, around cylinder walls,
upward into cylinder head through the thermostat,
and then back to the radiator.
During engine warm-up and while thermostat
is closed, coolant is recirculated within the engine
until thermostat opening temperature is reached.
G M C S E R V I C E M A N U A L
SECTION 6K
V6 GASOLINE ENGINES
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 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 recirculated
back into water pump and engine.
Figure 1— Coolant Circulation (V 6 Engine) ITypical)
The water pump, belt-driven from the engine
Sec. 6K
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