1994 GMC SIERRA engine

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.
5-19
ProCarManuals.com

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.
5-20
ProCarManuals.com

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.)
5-21
ProCarManuals.com

... . . , .. ..,. ~.
NOTICE:
In cold weather, water can freeze and crack the engine, radiator, \
heater
core and other parts. So use the recommended coolant.
5 -22
ProCarManuals.com

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).
5-24
ProCarManuals.com

..I . ... . ;. ..
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 UfluSual 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.
5-25
ProCarManuals.com

Service & Appearance Care
Section
Here you will find information about the care of your vehicle . This section
begins with service and fuel information. and then it shows how to check
important fluid and lubricant levels
. There is also technical information
about your vehicle. and a section devoted to its appearance care
.
Service ................................................... 6-3
Fuel (Gasoline Engines)
...................................... 6-4
Diesel Fuel Requirements and Fuel System
...................... 6-5
Checking Things Under the Hood
............................. 6-15
HoodRelease
.......................................... 6-15
Cleaning Your Diesel Engine
.............................. 6-16
Noise Control System .................................... 6-16
Engine Oil (Except Diesel)
................................ 6-17
Engine Oil (Diesel Engines)
............................... 6-24
iri
Air Cleaner ............................................ 6-29
Automatic Fluid ........................................ 6-30
ManualFluid
........................................... 6-33
Hydraulic Clutch
........................................ 6-34
RearAxle ............................................. 6-35
mnsfer Case
.......................................... 6-36
FrontAxle
............................................. 6-37
Engine Coolant
......................................... 6-38
Power Steering Fluid
.................................... 6-43
6-1
ProCarManuals.com

NOTICE:
If you try to do your own service work without knowing enough
about it, your vehicle could be damaged.
__ .
Maintenance Schedule
Section 7 of this manual, “Scheduled Maintenance Services”, explains the
maintenance your new vehicle needs, and when
it should be done. It also
has a form that you can use to record the maintenance work done on your
vehicle. Be sure
to read this information.
Fuel (Gasoline Engine)
If your vehicle has a diesel engine, see “Diesel Fuel Requirements and Fuel
System” in this Section. For vehicles with gasoline engines, please read this.
Use regular unleaded gasoline rated at
87 octane or higher. It should meet
specifications
ASTM D48 14 in the U.S. and CGSB 3.5-92 in Canada.
These fuels should have the proper additives, so you should not have to add
anything to the
fuel.
In the U.S. and Canada, it’s easy to be sure you get the right kind of
gasoline (unleaded). You’ll see “UNLEADED” right on the pump. And only
unleaded nozzles will fit into your vehicle’s filler neck.
Be sure
the posted octane is at least 87. If the octane is less than 87, you
may get a heavy knocking noise when
you drive. If it’s bad enough, it can
damage your engine.
If you’re using fuel rated at 87 octane or higher and you still hear heavy
knocking, your engine needs service. But don’t worry if
you hear a little
pinging noise
when you’re accelerating or driving up a hill. That’s normal
and
you don’t have to buy a higher octane fuel to get rid of pinging. It’s the
heavy, constant knock that means you have
a problem.
What about gasoline with blending materials that contain oxygen
(oxygenates), such as
MTBE or alcohol?
MTBE is “methyl tertiary-butyl ether.’’ Fuel that is no more than 15%
MTBE is fine for your vehicle.
Ethanol is ethyl or grain alcohol. Properly-blended fuel that is no more than
10% ethanol is fine for your vehicle.
Methanol is methyl or wood alcohol.
6-4
ProCarManuals.com