2018 GMC SIERRA overheating

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
360 Vehicle Care
6.0L V8 Engine
1. Coolant Surge Tank
2. Coolant Surge TankPressure Cap
3. Engine Belt-Driven Cooling Fan (Out of View)
{Warning
An underhood electric fan can
start up even when the engine is
not running and can cause injury.
Keep hands, clothing, and tools
away from any underhood
electric fan.
{Warning
Do not touch heater or radiator
hoses, or other engine parts.
They can be very hot and can
burn you. Do not run the engine if
there is a leak; all coolant could
leak out. That could cause an
engine fire and can burn you. Fix
any leak before driving the
vehicle.
Engine Coolant
The cooling system in the vehicle is
filled with DEX-COOL engine
coolant. This coolant is designed to
remain in the vehicle for 5 years or
240 000 km (150,000 mi), whichever
occurs first.
The following explains the cooling
system and how to check and add
coolant when it is low. If there is a
problem with engine overheating,
see Engine Overheating 0363.
What to Use
{Warning
Plain water, or other liquids such
as alcohol, can boil before the
proper coolant mixture will. With
plain water or the wrong mixture,
the engine could get too hot but
there would not be an overheat
warning. The engine could catch
fire and you or others could be
burned.
Use a 50/50 mixture of clean,
drinkable water and DEX-COOL
coolant. This mixture:
. Gives freezing protection down
to−37 °C (−34 °F), outside
temperature.
. Gives boiling protection up to
129 °C (265 °F), engine
temperature.
. Protects against rust and
corrosion.
. Will not damage aluminum parts.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
Vehicle Care 363
6. Verify coolant level after theengine is shut off and the
coolant is cold. If necessary,
repeat coolant fill procedure
Steps 1–6.
Caution
If the pressure cap is not tightly
installed, coolant loss and 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 supplement.
Caution
Do not run the engine if there is a
leak in the engine cooling system.
This can cause a loss of all
coolant and can damage the
system and vehicle. Have any
leaks fixed right away. The vehicle has several indicators
to warn of engine overheating.
There is a coolant temperature
gauge in the vehicle's instrument
cluster. See
Engine Coolant
Temperature Gauge 0144.
In addition, there are ENGINE
OVERHEATED STOP ENGINE,
ENGINE OVERHEATED IDLE
ENGINE, and ENGINE POWER IS
REDUCED messages in the Driver
Information Center (DIC).
If the decision is made not to lift the
hood when this warning appears,
get service help right away. See
Roadside Assistance Program
0 469.
If the decision is made to lift the
hood, make sure the vehicle is
parked on a level surface.
4.3L V6, 5.3L V8, and 6.2L
V8 Engines
Check to see if the engine cooling
fans are running. If the engine is
overheating, the fans should be running. If they are not, do not
continue to run the engine and have
the vehicle serviced.
If Steam is Coming from the
Engine Compartment
{Warning
Steam and scalding liquids from a
hot cooling system are under
pressure. Turning the pressure
cap, even a little, can cause them
to come out at high speed and
you could be burned. Never turn
the cap when the cooling system,
including the pressure cap, is hot.
Wait for the cooling system and
pressure cap to cool.
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.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
Vehicle Care 389
Wheels and Tires
Tires
Every new GM vehicle has
high-quality tires made by a
leading tire manufacturer. See
the warranty manual for
information regarding the tire
warranty and where to get
service. For additional
information refer to the tire
manufacturer.
{Warning
.Poorly maintained and
improperly used tires are
dangerous.
.Overloading the tires can
cause overheating as a
result of too much
flexing. There could be a
blowout and a serious
crash. SeeVehicle Load
Limits 0248.
(Continued)
Warning (Continued)
.Underinflated tires pose
the same danger as
overloaded tires. The
resulting crash could
cause serious injury.
Check all tires frequently
to maintain the
recommended pressure.
Tire pressure should be
checked when the tires
are cold.
.Overinflated tires are
more likely to be cut,
punctured, or broken by
a sudden impact —such
as when hitting a pothole.
Keep tires at the
recommended pressure.
.Worn or old tires can
cause a crash. If the
tread is badly worn,
replace them.
(Continued)
Warning (Continued)
.Replace any tires that
have been damaged by
impacts with potholes,
curbs, etc.
.Improperly repaired tires
can cause a crash. Only
the dealer or an
authorized tire service
center should repair,
replace, dismount, and
mount the tires.
.Do not spin the tires in
excess of 56 km/h
(35 mph) on slippery
surfaces such as snow,
mud, ice, etc. Excessive
spinning may cause the
tires to explode.
All-Season Tires
This vehicle may come with
all-season tires. These tires are
designed to provide good overall

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
398 Vehicle Care
Caution
Neither tire underinflation nor
overinflation is good.
Underinflated tires, or tires
that do not have enough air,
can result in:
.Tire overloading and
overheating which could
lead to a blowout.
.Premature or
irregular wear.
.Poor handling.
.Reduced fuel economy.
Overinflated tires, or tires that
have too much air, can
result in:
.Unusual wear.
.Poor handling.
.Rough ride.
.Needless damage from
road hazards. The Tire and Loading
Information label on the vehicle
indicates the original equipment
tires and the correct cold tire
inflation pressures. The
recommended pressure is the
minimum air pressure needed to
support the vehicle's maximum
load carrying capacity.
For additional information
regarding how much weight the
vehicle can carry, and an
example of the Tire and Loading
Information label, see
Vehicle
Load Limits 0248. How the
vehicle is loaded affects vehicle
handling and ride comfort. Never
load the vehicle with more
weight than it was designed to
carry.
When to Check
Check the tires once a month
or more. Do not forget the spare tire,
if the vehicle has one. See
Full-Size Spare Tire
0425 for
additional information.
How to Check
Use a good quality pocket-type
gauge to check tire pressure.
Proper tire inflation cannot be
determined by looking at the tire.
Check the tire inflation pressure
when the tires are cold, meaning
the vehicle has not been driven
for at least three hours or no
more than 1.6 km (1 mi).
Remove the valve cap from the
tire valve stem. Press the tire
gauge firmly onto the valve to
get a pressure measurement.
If the cold tire inflation pressure
matches the recommended
pressure on the Tire and
Loading Information label, no
further adjustment is necessary.
If the inflation pressure is low,
add air until the recommended
pressure is reached. If the

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
494 Index
D
Damage Repair, Collision . . . . . . . 472
Danger, Warning, and Caution . . . . 3
Data CollectionInfotainment System . . . . . . . . . . 478
OnStar . . . . . . . . . . . . . . . . . . . . . . . 478
Data Recorders, Event . . . . . . . . . 477
Daytime Running Lamps (DRL) . . . . . . . . . . . . . . . . . . 179
Defensive Driving . . . . . . . . . . . . . . . 236
Diagnostics
OnStar . . . . . . . . . . . . . . . . . . . . . . . 484
Distracted Driving . . . . . . . . . . . . . . . 235
Dome Lamps . . . . . . . . . . . . . . . . . . . 183
Door Ajar Light . . . . . . . . . . . . . . . . . . . . . 158
Locks . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Power Locks . . . . . . . . . . . . . . . . . . . . 41
Drive Belt Routing, Engine . . . . . . 464
Driver Assistance Systems . . . . . 288
Driver Information
Center (DIC) . . . . . . . . . . . . . 158, 160
Driving Assistance Systems . . . . . . . . . . 292
Characteristics and
Towing Tips . . . . . . . . . . . . . . . . . 303
Defensive . . . . . . . . . . . . . . . . . . . . . 236
Drunk . . . . . . . . . . . . . . . . . . . . . . . . . 236 Driving (cont'd)
For Better Fuel Economy . . . . . . . 33
Hill and Mountain Roads . . . . . . 245
If the Vehicle is Stuck . . . . . . . . . 247
Loss of Control . . . . . . . . . . . . . . . 238
Off-Road . . . . . . . . . . . . . . . . . . . . . 239
Off-Road Recovery . . . . . . . . . . . 238
Vehicle Load Limits . . . . . . . . . . . 248
Wet Roads . . . . . . . . . . . . . . . . . . . 244
Winter . . . . . . . . . . . . . . . . . . . . . . . . 245
Dual Automatic Climate Control System . . . . . . . . . . . . . . . . 228
E
E85 or FlexFuel . . . . . . . . . . . . . . . . 300
Electrical Equipment,Add-On . . . . . . . . . . . . . . . . . . . . . . . 336
Electrical System Engine Compartment Fuse
Block . . . . . . . . . . . . . . . . . . . . . . . . 381
Fuses and Circuit Breakers . . . 381
Instrument Panel Fuse Block . . . . . . . . . . . . . . . . . . . 385, 386
Overload . . . . . . . . . . . . . . . . . . . . . 380
Emergency OnStar . . . . . . . . . . . . . . . . . . . . . . . 480
Engine Air Cleaner/Filter . . . . . . . . . . . . . 358 Engine (cont'd)
Check Light (Malfunction
Indicator) . . . . . . . . . . . . . . . . . . . . 150
Compartment Overview . . . . . . . 345
Coolant Heater . . . . . . . . . . . . . . . 260
Coolant Temperature
Gauge . . . . . . . . . . . . . . . . . . . . . . 144
Coolant Temperature Warning Light . . . . . . . . . . . . . . . 155
Cooling System . . . . . . . . . . . . . . . 359
Drive Belt Routing . . . . . . . . . . . . 464
Exhaust . . . . . . . . . . . . . . . . . . . . . . 264
Fan . . . . . . . . . . . . . . . . . . . . . . . . . . . 365
Oil Life System . . . . . . . . . . . . . . . 353
Oil Pressure Gauge . . . . . . . . . . 143
Oil Pressure Light . . . . . . . . . . . . 156
Overheated Protection Operating Mode . . . . . . . . . . . . . 364
Overheating . . . . . . . . . . . . . . . . . . 363
Power Messages . . . . . . . . . . . . . 164
Running While Parked . . . . . . . . 265
Starting . . . . . . . . . . . . . . . . . . . . . . . 258
Entry Lighting . . . . . . . . . . . . . . . . . . . 184
Equipment, Towing . . . . . . . . . . . . . 325
Event Data Recorders . . . . . . . . . . 477
Exit Lighting . . . . . . . . . . . . . . . . . . . . 184
Extender, Seat Belt . . . . . . . . . . . . . . 75
Exterior Lamp Controls . . . . . . . . . 176

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
498 Index
Maintenance Schedule (cont'd)Recommended Fluids and
Lubricants . . . . . . . . . . . . . . . . . . . 456
Transfer Case . . . . . . . . . . . . . . . . 272
Malfunction Indicator Lamp . . . . . 150
Manual Mirrors . . . . . . . . . . . . . . . . . . 47
Manual Mode . . . . . . . . . . . . . . . . . . . 268
Manual Windows . . . . . . . . . . . . . . . . 52
Media Avoiding Untrusted Devices . . 195
Memory Features . . . . . . . . . . . . . . . . 13
Memory Seats . . . . . . . . . . . . . . . . . . . 62
Messages Engine Power . . . . . . . . . . . . . . . . 164
Vehicle . . . . . . . . . . . . . . . . . . . . . . . 164
Vehicle Speed . . . . . . . . . . . . . . . . 164
Mirrors Automatic Dimming . . . . . . . . . . . . . 50
Automatic Dimming
Rearview . . . . . . . . . . . . . . . . . . . . . . 52
Blind Spot . . . . . . . . . . . . . . . . . . . . . . 50
Convex . . . . . . . . . . . . . . . . . . . . . . . . . 47
Folding . . . . . . . . . . . . . . . . . . . . . . . . . 49
Heated . . . . . . . . . . . . . . . . . . . . . . . . . 50
Manual . . . . . . . . . . . . . . . . . . . . . . . . . 47
Manual Rearview . . . . . . . . . . . . . . . 52
Power . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Tilt in Reverse . . . . . . . . . . . . . . . . . . 51 Mirrors (cont'd)
Trailer Tow . . . . . . . . . . . . . . . . . . . . . . 48
Mirrors, Interior Rearview . . . . . . . . 51
Monitor System, Tire Pressure . . . . . . . . . . . . . . . . . . . . . . 399
Multi-band Antenna . . . . . . . . . . . . . 194
N
Navigation OnStar . . . . . . . . . . . . . . . . . . . . . . . 481
New Vehicle Break-In . . . . . . . . . . . 255
Noise Control System . . . . . . . . . . 373
O
Odometer . . . . . . . . . . . . . . . . . . . . . . . 142 Trip . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
Off-Road . . . . . . . . . . . . . . . . . . . . . . . 239 Driving . . . . . . . . . . . . . . . . . . . . . . . . 239
Recovery . . . . . . . . . . . . . . . . . . . . . 238
Oil
Engine . . . . . . . . . . . . . . . . . . . . . . . . 350
Engine Oil Life System . . . . . . . 353
Engine Oil Pressure Gauge . . . 143
Pressure Light . . . . . . . . . . . . . . . . 156
Older Children, Restraints . . . . . . . 92
Online Owner Center . . . . . . . . . . . 468
OnStar . . . . . . . . . . . . . . . . . . . . . . . . . 478
OnStar Additional Information . . . . . . . . . . . . . . . . . . . . 485 OnStar Connections . . . . . . . . . . . . 482
OnStar Diagnostics . . . . . . . . . . . . . 484
OnStar Emergency . . . . . . . . . . . . . 480
OnStar Navigation . . . . . . . . . . . . . . 481
OnStar Overview . . . . . . . . . . . . . . . 479
OnStar Security . . . . . . . . . . . . . . . . 481
Operating Mode
Overheated EngineProtection . . . . . . . . . . . . . . . . . . . 364
Operation Fog Lamps . . . . . . . . . . . . . . . . . . . 181
Ordering Service Publications . . . . . . . . . . 474
Outlets Power . . . . . . . . . . . . . . . . . . . . . . . . 133
Overheated Engine
Protection Operating Mode . . . . 364
Overheating, Engine . . . . . . . . . . . . 363
Overview . . . . . . . . . . . . . . . . . . . . . . . 188
P
Park Shifting Into . . . . . . . . . . . . . . . . . . . 262
Shifting Out of . . . . . . . . . . . . . . . . 263
Parking Brake . . . . . . . . . . . . . . . . . . . . . . . . . 281
Brake and P (Park)
Mechanism Check . . . . . . . . . . 375