1999 CHEVROLET CORVETTE engine

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6-17
CAUTION:
Operating the engine with the air cleaner/filter
off can cause you or others to be burned. The air
cleaner not only cleans the air, it stops flame if
the engine backfires. If it isn't there, and the
engine backfires, you could be burned. Don't
drive with it off, and be careful working on the
engine with the air cleaner/filter off.
NOTICE:
If the air cleaner/filter is off, a backfire can cause
a damaging engine fire. And, dirt can easily get
into your engine, which will damage it. Always
have the air cleaner/filter in place when
you're driving.
Air Cleaner/Filter Replacement
To remove the air cleaner/filter:
1. Pull up on the clips on each side to release
the assembly.

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6-19
Change both the fluid and filter every 50,000 miles
(80 000 km) if the vehicle is mainly driven under one of
these conditions:

In heavy city traffic where the outside temperature
regularly reaches 90F (32C) or higher.

In hilly or mountainous terrain.

High performance operation.
If you do not use your vehicle under one of these
conditions, change the fluid and filter every
100,000 miles (166 000 km).
See ªScheduled Maintenance Servicesº in the Index for
the proper service intervals for the transmission fluid
and filter.
Manual Transmission Fluid
When to Check
A good time to have it checked is when the engine oil is
changed. However, the fluid in your manual
transmission doesn't require changing.
How to Check
Because this operation can be difficult, you may choose
to have this done at your Chevrolet dealership
Service Department.
If you do it yourself, be sure to follow all the
instructions here, or you could get a false reading.
NOTICE:
Too much or too little fluid can damage your
transmission. Too much can mean that some
of the fluid could come out and fall on hot
exhaust system parts, starting a fire. Be sure
to get an accurate reading if you check your
transmission fluid.
Check the fluid level only when your engine is off, the
vehicle is parked on a level place and the transmission is
cool enough for you to rest your fingers on the
transmission case.

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6-21 When to Check and What to Use
Refer to the Maintenance Schedule to determine how
often you should check the fluid level in your clutch
master cylinder reservoir and for the proper fluid. See
ªOwner Checks and Servicesº and ªRecommended
Fluids and Lubricantsº in the Index.
How to Check and Add Fluid
The clutch master cylinder is on the driver's side of the
engine compartment, near the fender.
To check the fluid, remove the cap and rubber seal.
Fluid should be added if the fluid level is below the step
on the inside of the reservoir. There are additional
instructions on the reservoir cap.
Replace the rubber seal and cap.
Rear Axle
When to Check Lubricant
Refer to the Maintenance Schedule to determine how
often to check the lubricant. See ªPeriodic Maintenance
Inspectionsº in the Index.

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6-22 How to Check Lubricant
If the level is below the bottom of the filler plug hole,
you'll need to add some lubricant. Add enough lubricant
to raise the level to the bottom of the filler plug hole.
What to Use
To add lubricant when the level is low, use SAE 75W-90
Synthetic Gear Lubricant (GM Part No. 12378261) or
equivalent meeting GM Specification 9986115. To
completely refill after draining, add 4 ounces (118 ml)
of Limited
-Slip Differential Lubricant Additive
(GM Part No. 1052358) or equivalent. Then fill to
the bottom of the filler plug hole with the Synthetic
Gear Lubricant.
Surge Tank Pressure Cap
NOTICE:
The surge tank pressure cap is a 15 psi (105 kPa)
pressure
-type cap and must be tightly installed to
prevent coolant loss and possible engine damage
from overheating.
When you replace the surge tank pressure cap, a GM cap
is recommended.

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6-23
Thermostat
Engine coolant temperature is controlled by a thermostat
in the engine coolant system. The thermostat stops the
flow of coolant through the radiator until the coolant
reaches a pre
-set temperature.
When you replace the thermostat, a GM thermostat
is recommended.
Engine Coolant
The cooling system in your vehicle is filled with
DEX
-COOL
engine coolant. This coolant is designed
to remain in your vehicle for 5 years or 150,000 miles
(240 000 km), whichever occurs first, if you add only
DEX
-COOL
extended life coolant.
The following explains your cooling system and how
to add coolant when it is low. If you have a problem
with engine overheating, see ªEngine Overheatingº in
the Index.A 50/50 mixture of clean, drinkable water and
DEX
-COOL
coolant will:

Give freezing protection down to
-34F (-37C).

Give boiling protection up to 265F (129C).

Protect against rust and corrosion.

Help keep the proper engine temperature.

Let the warning lights and gages work as
they should.
NOTICE:
When adding coolant, it is important that you
use only DEX
-COOL (silicate-free) coolant.
If coolant other than DEX-COOL is added to
the system, premature engine, heater core or
radiator corrosion may result. In addition, the
engine coolant will require change sooner
-- at
30,000 miles (50 000 km) or 24 months,
whichever occurs first. Damage caused by the
use of coolant other than DEX
-COOL is not
covered by your new vehicle warranty.

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6-24 What to Use
Use a mixture of one-half clean, drinkable water and
one
-half DEX-COOL
coolant which won't damage
aluminum parts. If you use this coolant mixture, you
don't need to add anything else.
CAUTION:
Adding only plain water to your cooling system
can be dangerous. Plain water, or some other
liquid like alcohol, can boil before the proper
coolant mixture will. Your vehicle's coolant
warning system is set for the proper coolant
mixture. With plain water or the wrong mixture,
your engine could get too hot but you wouldn't
get the overheat warning. Your engine could
catch fire and you or others could be burned. Use
a 50/50 mixture of clean, drinkable water and
DEX
-COOL
coolant.
NOTICE:
If you use an improper coolant mixture, your
engine could overheat and be badly damaged.
The repair cost wouldn't be covered by your
warranty. Too much water in the mixture can
freeze and crack the engine, radiator, heater core
and other parts.
If you have to add coolant more than four times a year,
have your dealer check your cooling system.
NOTICE:
If you use the proper coolant, you don't have to
add extra inhibitors or additives which claim to
improve the system. These can be harmful.

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6-25 Checking Coolant
The coolant surge tank is in the engine compartment
behind the passenger's side headlamp.
CAUTION:
Turning the surge tank pressure cap when the
engine and radiator are hot can allow steam and
scalding liquids to blow out and burn you badly.
Never turn the surge tank pressure cap
-- even a
little
-- when the engine and radiator are hot.
The vehicle must be on a level surface. When your
engine is cold, the coolant level should be at the
FULL COLD mark. The FULL COLD mark is on
the front of the coolant surge tank. Don't overfill the
surge tank. Too much coolant can result in an overflow
when the fluid is hot.
If the LOW COOLANT message comes on and stays
on, it means you're low on engine coolant.

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6-26
Adding Coolant
If you need more coolant, add the proper DEX
-COOL

coolant mixture at the surge tank, but only when the
engine is cool.
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. Don't spill coolant on a hot engine.
When replacing the pressure cap, make sure it
is hand
-tight.
Power Steering Fluid
When to Check Power Steering Fluid
It is not necessary to regularly check power steering
fluid unless you suspect there is a leak in the system or
you hear an unusual noise. A fluid loss in this system
could indicate a problem. Have the system inspected
and repaired.