1994 GMC SIERRA Owners Manual

How to Add Coolant to the Radiator
1. You can remove the radiator pressure cap when the cooling system,
including the radiator pressure cap and upper radiator hose, is no longer
hot.
Turn the pressure cap slowly to the left until it first stops. (Don’t press
down while turning the pressure cap.)
If you hear a hiss, wait for that
to stop. A hiss means there is still some
pressure left.
I
r
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3. Fill the radiator
with the proper
mix, up to the
base
of the filler
neck.
4. Then fill the
coolant recovery
tank
to the
COLD mark.
5. Put the cap back
on the coolant
recovery tank,
but leave the
radiator pressure cap
off.
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I 6. Start the engine
and let it run
until
you can feel the
upper radiator
hose getting hot.
Watch out for
the
engine fan(s).
7. By this time the coolant level inside the radiator filler neck may be
lower.
If the level is lower, add more of the proper mix through the
filler neck until the level reaches the hase
of the filler neck.
8. Then replace the
pressure cap. At
any time during
this procedure
if
coolant begins to
flow out of the
filler neck,
reinstall the
pressure cap. Be
sure the arrows
on pressure cap
line up like this.
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A CAUTION:
If your vehicle has air conditioning, the auxiliary electric fa\
n
under the hood can start up even when the engine
is not running
and can injure you. Keep hands, clothing and tools away
from
any underhood electric fan.
If the coolant inside the coolant surge tank is boiling, don’t do anything else
until it cools down.
E The coolant level
should be slightly
above the
COLD
mark. If it isn’t, you
may have a leak in the
radiator hoses, heater
hoses, radiator, water
pump or somewhere
else
in the cooling
system.
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I NOTICE:
Engine damage from running your engine without coolant isn’t \
covered
by your warranty.
If there seems to be no leak, start the engine again. See if the fan speed
increases when idle speed
is doubled by pushing the accelerator pedal down.
If it doesn’t, your vehicle needs service. Turn off the engine.
How to Add Coolant to the Coolant Surge lank
If you haven’t found a problem yet, but the coolant level isn’t at the COLD
mark add a 50/50 mixture of clean water (preferably distilled) and a proper
antifreeze at the coolant surge tank, but be sure the cooling system,
including the coolant surge tank pressure cap, is cool before you do
it. (See
“Engine Coolant”
in the Index for more information about the proper
coolant mix.)
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... . . , .. ..,. ~.
NOTICE:
In cold weather, water can freeze and crack the engine, radiator, \
heater
core and other parts. So use the recommended coolant.
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1. You can remove the coolant surge tank pressure cap when the coolin\
g
system, including the coolant surge tank pressure cap and upper\

radiator hose, is no longer hot.
I
Turn the pressure cap slowly to the left until it first stops. (Don't press
down while turning the pressure cap.)
If you hear a hiss, wait for that to stop. A hiss means there is still some
pressure left.
2. Then keep
turning the cap,
but now push down as
you turn
it. Remove the
pressure cap.
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3. Open the air
bleed valve
located on the
thermostat
housing.
4. Fill the coolant
surge tank with
the proper mix,
up to the
COLD
mark.
While filling the surge tank, watch to see
if coolant begins to stream
out the air bleed valve. When coolant begins to stream out, close the
valve.
>. _:
5. With the air bleed
valve closed and
the coolant surge
tank pressure cap
off, start the
engine and let it
run until
you can
feel the upper
radiator hose getting hot.
Watch out for the
engine fan(s).
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