engine CHEVROLET SUBURBAN 1994 Repair Manual

If Steam Is Coming From Your Engine
I NOTICE:
If your engine catches fire because you keep driving with no
coolant, your vehicle
can be badly damaged. The costly repairs
would not be covered
by your warranty.
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If No Steam Is Coming From Your Engine
If you get the overheat warning but see or hear no steam, the problem may
not be too serious. Sometimes the engine can get a little too hot when you:
Climb a long hill on a hot day.
Stop after high speed driving.
Idle for long periods in traffic.
Tow a trailer.
If you get the overheat warning with no sign of steam, try this for a minute
or
so:
1. If you have an air conditioner, turn it off.
2. Turn on your heater to full hot at the highest fan speed and open the
3. If you’re in a traffic jam, shift to “N’ (Neutral).
window
as necessary.
If you
no longer have the overheat warning, you can drive. Just to be safe,
drive slower for about ten minutes. If the warning doesn’t come back on,
you can drive normally.
If the warning continues, pull over, stop, and park your vehicle right away.
If there’s still
no sign of steam, push the accelerator until the engine speed is
about twice as fast as normal idle speed. Bring the engine speed back to
normal idle speed after two or three minutes. Now see
if the warning stops.
But then, if
you still have the warning, TURN OFF THE ENGINE AND
GET EVERYONE OUT OF THE VEHICLE until it cools down.
You may decide not to lift the hood but to get service help right away.
Cooling System -Gas Engines
When you decide it’s
safe to lift the hood,
here’s what you’ll see:
A. Coolant recovery
“I tank
B. Engine fan(s)
C. Radiator pressure
cap
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If the coolant inside the coolant recovery tank is boiling, don’t do anything
else until it cools down.
P
The coolant level
should be at or 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.
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.
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How to Add Coolant to the Coolant Recovery Tank
If you haven’t found a problem yet, but the coolant level isn’t at or above
the
COLD mark, add a 50/50 mixture of clean water (preferably distilled)
and a proper antifreeze at the coolant recovery tank. (See “Engine Coolant”
in the Index for more information about the proper coolant mix.)
NOTICE:
In cold weather, water can freeze and crack the engine, radiator, \
heater core and other parts.
Use the recommended coolant.
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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).
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 base 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.
Cooling System -Diesel Engines
When you decide it's
safe
to lift the hood,
here's what
you'll see:
A
A. Coolant surge
tank pressure cap
B. Engine fan(s)
C. Radiator
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If the coolant inside the coolant surge tank is boiling, don't do anything else
until it cools down.
The coolant level
should be at
or 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.
NOTICE:
Engine damage from running your engine without coolant isn't
covered by your warranty.
If there seems to be no leak, start the engifie 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.
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How to Add Coolant to the Coolant Surge Tank
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, radiat\
or,
heater core and other parts.
So use the recommended coolant.
1. You can remove the coolant surge tank pressure cap when the cooling
system, including the coolant surge tank pressure cap and upper
radiator
hose, is no longer hot.
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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).
6. By this time, the coolant level inside the coolant surge tank may be
lower.
If the level is lower, add more of the proper mix to the coolant
surge tank until the level reaches the
COLD mark.
7. Then replace the
pressure cap.
Be
sure the arrows
on the pressure
cap line up like
this.
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Engine Fan Noise
Your vehicle has a clutched engine cooling fan. When the clutch is engaged,
the fan spins faster to provide more air to cool
the engine. In most every day
driving conditions the fan
is spinning slower and clutch is not fully engaged.
This improves
fuel economy and reduces fan noise. Under heavy vehicle
loading, trailer towing and/or high outside temperatures, the fan speed
increases as the clutch more fully engages.
So you may hear an increase in
fan noise. This is normal and should not be mistaken as the transmission
slipping or making extra shifts.
It is merely the cooling system functioning
properly. The
fan will slow down when additional cooling is not required
and the clutch partially disengages.
You may also hear this fan noise when you start the engine. It will go away
as the fan clutch partially disengages.
If a Tire Goes Flat
It’s unusual for a tire to “blow out” while you’re driving, especially if you
maintain your tires properly. If air goes out of a tire, it’s much more likely to
leak out slowly. But if you should ever have
a “blowout,” here are a few tips
about what to expect and what
to do:
If a front tire fails, the flat tire will create a drag that pulls the vehicle
toward that side. Take your foot off the accelerator pedal and grip the
steering wheel firmly. Steer to maintain lane position, then gently brake to a
stop well out of the traffic lane.
A rear blowout, particularly on a curve, acts much like a skid and may
require the same correction you’d use in a skid. In any rear blowout, remove
your foot from the accelerator pedal. Get the vehicle under control
by
steering the way you want the vehicle to go. It may be very bumpy and
noisy, but you can still steer. Gently brake to a stop, well off the road if
possible.
If a
tire goes flat, the next section shows how to use your jacking equipment
to change a flat tire safely.
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