2009 GMC SIERRA engine overheat

Notice:If an improper coolant mixture is used,
the engine could overheat and be badly damaged.
The repair cost would not be covered by the vehicle
warranty. Too much water in the mixture can freeze
and crack the engine, radiator, heater core, and
other parts.
Notice:If extra inhibitors and/or additives are used
in the vehicle’s cooling system, the vehicle could
be damaged. Use only the proper mixture of
the engine coolant listed in this manual for the
cooling system. SeeRecommended Fluids and
Lubricants on page 6-15for more information.Checking Coolant
The coolant surge tank is located in the engine
compartment on the passenger side of the vehicle.
SeeEngine Compartment Overview on page 5-14for
more information on location.
The vehicle must be on a level surface when checking
the coolant level.
Check to see if coolant is visible in the coolant surge tank.
If the coolant inside the coolant surge tank is boiling,
do not do anything else until it cools down. If coolant is
visible but the coolant level is not at or above the FULL
COLD mark, add a 50/50 mixture of clean, drinkable
water and DEX-COOL
®coolant at the coolant surge tank,
but be sure the cooling system is cool before this is done.
5-31

The coolant level should be at or above the FULL
COLD mark. If it is not, you may have a leak in the
cooling system.
If the vehicle has a low coolant sensor and the LOW
COOLANT LEVEL message comes on and stays on,
it means you are low on engine coolant. See “LOW
COOLANT LEVEL” underDIC Warnings and Messages
on page 3-66.
How to Add Coolant to the Coolant
Surge Tank for Gasoline Engines
If the vehicle has a diesel engine, see “Cooling System”
in the DURAMAX®Diesel Supplement for the proper
coolant ll procedure.
{CAUTION:
You can be burned if you spill coolant on hot
engine parts. Coolant contains ethylene glycol and
it will burn if the engine parts are hot enough.
Do not spill coolant on a hot engine.
Notice:This vehicle has a specic coolant ll
procedure. Failure to follow this procedure could
cause the engine to overheat and be severely
damaged.
5-32

3. Fill the coolant surge tank with the proper mixture
to the FULL COLD mark.
4. With the coolant surge tank pressure cap off,
start the engine and let it run until the engine
coolant temperature gage indicates approximately
195°F (90°C).
By this time, the coolant level inside the coolant
surge tank may be lower. If the level is lower, add
more of the proper mixture to the coolant surge tank
until the level reaches the FULL COLD mark.5. Replace the pressure cap. Be sure the pressure
cap is hand-tight and fully seated.
6. Verify coolant level after engine is shut off and the
coolant is cold. If necessary, repeat coolant ll
procedure Steps 1 through 6.
Notice:If the pressure cap is not tightly installed,
coolant loss and possible engine damage may occur.
Be sure the cap is properly and tightly secured.
Engine Overheating
If the vehicle has the DURAMAX®Diesel engine, see
the DURAMAX®Diesel manual for more information.
The vehicle has several indicators to warn of engine
overheating.
You will nd a coolant temperature gage on the vehicle’s
instrument panel. SeeEngine Coolant Temperature
Gage on page 3-44.
In addition, you will nd ENGINE OVERHEATED STOP
ENGINE, ENGINE OVERHEATED IDLE ENGINE, and
ENGINE POWER IS REDUCED messages in the Driver
Information Center (DIC) on the instrument panel. See
DIC Warnings and Messages on page 3-66.
5-34

You may decide not to lift the hood when this warning
appears, but instead get service help right away.
SeeRoadside Assistance Program on page 7-7.
If you do decide to lift the hood, make sure the vehicle
is parked on a level surface.
Then check to see if the engine cooling fans are
running. If the engine is overheating, both fans should
be running. If they are not, do not continue to run
the engine and have the vehicle serviced.
Notice:Engine damage from running your engine
without coolant is not covered by your warranty.
SeeOverheated Engine Protection Operating Mode
on page 5-37for information on driving to a safe
place in an emergency.
Notice:If the engine catches re while driving with
no coolant, the vehicle can be badly damaged.
The costly repairs would not be covered by
the vehicle warranty. SeeOverheated Engine
Protection Operating Mode on page 5-37for
information on driving to a safe place in an
emergency.If Steam Is Coming From The Engine
Compartment
{CAUTION:
Steam from an overheated engine can burn you
badly, even if you just open the hood. Stay away
from the engine if you see or hear steam coming
from it. Turn it off and get everyone away from
the vehicle until it cools down. Wait until there
is no sign of steam or coolant before you open
the hood.
If you keep driving when the vehicles engine is
overheated, the liquids in it can catch re. You or
others could be badly burned. Stop the engine if it
overheats, and get out of the vehicle until the
engine is cool.
SeeOverheated Engine Protection Operating
Mode on page 5-37for information on driving to a
safe place in an emergency.
5-35

If No Steam Is Coming From The
Engine Compartment
The ENGINE OVERHEATED STOP ENGINE or the
ENGINE OVERHEATED IDLE ENGINE message, along
with a low coolant condition, can indicate a serious
problem.
If you get an engine 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. SeeTowing a Trailer on page 4-51.If you get the ENGINE OVERHEATED STOP ENGINE or
the ENGINE OVERHEATED IDLE ENGINE message
with no sign of steam, try this for a minute or so:
1. Turn the air conditioning off.
2. Turn the heater on to the highest temperature and
to the highest fan speed. Open the windows as
necessary.
3. If you are stopped in a traffic jam, apply the brake,
shift to N (Neutral); otherwise, shift to the highest
gear while driving—D(Drive) or 3 (Third).
If the temperature overheat gage is no longer in the
overheat zone or an overheat warning no longer displays,
the vehicle can be driven. Continue to drive the vehicle
slow for about 10 minutes. Keep a safe vehicle distance
from the car in front of you. If the warning does not come
back on, continue to drive normally.
If the warning continues, pull over, stop, and park the
vehicle right away.
If there is no sign of steam, idle the engine for
ve minutes while parked. If the warning is still
displayed, turn off the engine until it cools down.
Also, see “Overheated Engine Protection Operating
Mode” later in this section.
5-36

Overheated Engine Protection
Operating Mode
If an overheated engine condition exists and the
REDUCED ENGINE POWER message is displayed, an
overheat protection mode which alternates ring groups
of cylinders helps prevent engine damage. In this mode,
you will notice a loss in power and engine performance.
This operating mode allows the vehicle to be driven to a
safe place in an emergency. Driving extended miles (km)
and/or towing a trailer in the overheat protection mode
should be avoided.
Notice:After driving in the overheated engine
protection operating mode, to avoid engine damage,
allow the engine to cool before attempting any repair.
The engine oil will be severely degraded. Repair the
cause of coolant loss, change the oil and reset the oil
life system. SeeEngine Oil on page 5-15.
Engine Fan Noise
If the 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 everyday driving conditions,
the fan is spinning slower and the 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 disengages.
You may also hear this fan noise when you start the
engine. It will go away as the fan clutch partially
disengages.
If the vehicle has electric cooling fans, you may hear
the fans spinning at low speed during most everyday
driving. The fans may turn off if no cooling is required.
Under heavy vehicle loading, trailer towing, and/or
high outside temperatures, or if you are operating the
air conditioning system, the fans may change to
high speed and you may hear an increase in fan noise.
This is normal and indicates that the cooling system
is functioning properly. The fans will change to low
speed when additional cooling is no longer required.
5-37

Vehicles with P265/70R17 or P275/55R20 size tires
require ination pressure adjustment when driving the
vehicle at speeds of 100 mph (160 km/h) or higher.
Set the cold tire ination pressure to 3 psi (20 kPa)
above the recommended cold tire pressure shown on
the Tire and Loading Information label.
When you end this high-speed driving, return the tires
to the cold ination pressure shown on the Tire and
Loading Information label. SeeLoading the Vehicle on
page 4-32andInflation - Tire Pressure on page 5-73.
Dual Tire Operation
When the vehicle is new, or whenever a wheel, wheel bolt
or wheel nut is replaced, check the wheel nut torque after
100, 1,000 and 6,000 miles (160, 1 600 and 10 000 km)
of driving. For proper torque and wheel nut tightening
information, seeRemoving the Spare Tire and Tools on
page 5-93.The outer tire on a dual wheel setup generally wears
faster than the inner tire. Your tires will wear more
evenly and last longer if you rotate the tires periodically,
seeTire Inspection and Rotation on page 5-81. Also
seeScheduled Maintenance (Gasoline Engine) on
page 6-4.
{CAUTION:
If you operate your vehicle with a tire that is badly
underinated, the tire can overheat. An overheated
tire can lose air suddenly or catch re. You or
others could be injured. Be sure all tires (including
the spare) are properly inated.
SeeInflation - Tire Pressure on page 5-73, for
information on proper tire ination.
5-75

Electrical System (cont.)
Underhood Fuse Block...............................5-126
Windshield Wiper Fuses.............................5-122
Electronic Immobilizer
PASS-Key
®III+...........................................2-20
Electronic Immobilizer Operation
PASS-Key
®III+...........................................2-20
Engine
Air Cleaner/Filter.........................................5-19
Check and Service Engine Soon Lamp...........3-45
Coolant......................................................5-29
Coolant Heater............................................2-27
Coolant Temperature Gage...........................3-44
Drive Belt Routing.......................................6-18
Engine Compartment Overview......................5-14
Exhaust.....................................................2-55
Fan Noise..................................................5-37
Fast Idle System.........................................2-25
Oil .............................................................5-15
Oil Life System...........................................5-18
Overheated Protection Operating Mode...........5-37
Overheating................................................5-34
Starting......................................................2-24
Entry Lighting.................................................3-20
Event Data Recorders.....................................7-17
Exit Lighting...................................................3-20
Extender, Safety Belt.......................................1-37
Exterior Lamps...............................................3-16
F
Fast Idle System............................................2-25
Filter
Engine Air Cleaner......................................5-19
Finish Damage.............................................5-120
Fixed Mast Antenna.......................................3-142
Flashers, Hazard Warning.................................. 3-8
Flash-to-Pass.................................................3-10
Flat Tire........................................................5-91
Flat Tire, Changing.........................................5-92
Flat Tire, Storing...........................................5-109
Fluid
Automatic Transmission........................5-21, 5-24
Power Steering...........................................5-38
Windshield Washer......................................5-39
Fog Lamp
Fog ...........................................................3-19
Fog Lamp Light..............................................3-50
Four-Wheel Drive....................................2-37, 5-51
Four-Wheel-Drive Light....................................3-51
Front Axle......................................................5-53
Fuel............................................................... 5-6
Additives...................................................... 5-7
California Fuel.............................................. 5-7
Driving for Better Economy............................. 4-2
E85 (85% Ethanol)........................................ 5-8
Filling a Portable Fuel Container....................5-12
Filling the Tank...........................................5-10
5