2015 AUDI S8 AUX

228 Checking and filling
Checking and filling Engine hood
Releasing the engine hood
The engine hood is released from inside the
vehicle .
Fig. 197 Driver foo twell: release lever
Fig. 198 Rocker switch un der the hood
Make sure the wiper arms are not raised up
from the windshield. Otherwise the paint
could be damaged.
.,. Pull the lever under the instrument panel in
the direction of the arrow
¢ fig. 197.
.,. Raise the hood slightly¢,&. .
... Press the rocker switch under the hood up­
ward ~
fig. 198. This releases the catch.
• Open the hood.
&_ WARNING
Hot engine coolant can burn you.
- To reduce the risk of being burned, never
open the hood if you see or hear steam
or coolant escaping from the engine compartment . Wait until no steam or
coolant can be seen or heard before care­
fully opening the hood .
'Working in the engine compartment
Be especially careful whenever you work in
the engine compartment.
Whenever you must perform any work in the
engine compartment, for example checking
and filling different fluids, there is a risk of injury, burns and accidents. To prevent per­
sonal injury always observe the following
WARNINGS. The engine compartment of any
vehicle is a hazardous area
¢ ,&. .
A WARNING
To help avoid injury, before you check any­
thing under the hood:
- Turn off the engine.
- Switch off the ignition .
- Apply the parking brake.
- Move selector lever to "P" (Park) .
- Always let the engine cool down. Hot
components will burn skin on contact.
- To reduce the risk of being burned, never
open the hood if you see or hear steam
or coolant escaping from the engine
compartment. Wait until no steam or
coolant can be seen or heard before care­
fully opening the hood.
- Keep children away from the engine com­
partment.
- Never spill fluids on hot engine compo­
nents . They can cause a fire .
- Never touch the radiator fan. The auxili­
ary electric fan is temperature controlled
and can switch on suddenly .
- Never open the coolant reservoir cap
when the engine is still warm . The cool­
ant system is pressurized and hot cool­
ant could spray out.
- Protect your face, hands and arm from
steam or hot engine coolant by placing a
thick rag over the cap when you open the
coolant reservoir.
- Do not
remove the engine cover under
any circumstances. This increases the
risk of burns.
- If work on the fuel system or the electri­
cal system is necessary:

238 Check ing and filling
• Let the engine coo l down .
• Place a thick rag over the coolant expansion
tank
¢ page 237, fig . 204 and care full y
twist the cap counter-clockwise¢ _&..
• Add coolant mixed in the correct ratio
¢
page 236, Coolant up to the MAX mark­
i ng.
• Make sure that the fluid level rema ins sta-
ble. Add more coolant if necessary.
• Twist the cap on again
tightly.
Replacement engine coolant must conform to
exact specifications ¢
page 236, Coolant.
We recommend using only coolant additive
G12++, G13 or in an emergency G12+ . Do not
use a different additive . In an emergency use
p la in water unt il you can get the correct add i­
tive and can restore the correct ratio. This
should be done as soon as possible .
If you have lost a considerable amount of
coolant, then you should add co ld antifreeze
and cold water only when the engine is co ld.
Always use
new eng ine coolant when refilling .
Do not fi ll coolant above the "MAX" mark. Ex­
cess coolant will be forced out through the pressure relief valve in the cap when the en­
g ine becomes hot .
A WARNING
- T he coo ling system is under p ressure and
can get very hot. Reduce the risk of
scalding from ho t coolant by following
these steps.
-Turn off the eng ine and a llow it to cool
down.
- Protect your face, hands and arms from escaping flu id and steam by cover ing
the cap with a large, thick rag.
- T urn the cap slowly and very carefully
in a counter-clockwise d irect ion while
apply ing light, downward pressure on
the top of the cap.
- To avo id being burned, do not sp ill an­
tifreeze or coolant on the exhaust sys­
tem or hot engine parts . Under certa in cond
it ions, the ethylene g lycol in en­
gine coolant can catch fire.
- Antifreeze is poisonous . A lways store an­
tifreeze in its origina l container and well
out of the reach of children.
- If you dra in the coo lant, it must be
caught and safely stored in a proper con­
tainer clearly marked "po ison".
@ Note
- Do not add coolant if the expansion tank
is empty. Air co uld enter the cooling sys­
tem and damage the engine. If this is
the case, do not cont inue driving. Seek
professional assistance .
- Coo lant pollutes the environment and
cou ld cause an engine f ire. Excess cool­
ant will be forced out through the pres­
sure relief valve in the cap when the en­
gine becomes hot.
- If, in an eme rgency, only wate r can be
added, the co rrect ratio between water
and antifreeze ¢
page 236 must be re­
stored as soon as possible.
@ For the sake of the environment
D rained coolant should not be reused . Al­
ways d ispose of used coolant while observ­
i ng all envi ro nmental regula tions.
Radiator fan
The radiator fan switches on automatically by
itself
The rad iator fan is driven by the e ngine via the
V-belt. The viscous clutch regulates the speed of the fan acco rding to the temperatu re of the
coolant.
An auxiliary electric radiato r fan* sw itches on
and off depending on coolant temperature
and ot her vehicle ope rat ing condit io ns.
After you switch the eng ine off, the aux iliary
fan can continue running for up to 10 m inutes
- even w ith the ignition off .
It can even switch
o n aga in later by itself¢.& , if
1111>

- the temperature of the engine coolant rises
due to th e heat bui ld-up from the engine in
the engine compartment, or
- the engine compartment heats up because
the vehicle is parked in intense sunlight.
.&_ WARNING
- To reduce the r isk of personal injury nev­
er touch the radiator fan.
- The auxiliary electr ic fan is temperature
controlled and can switch on sudden ly
even when the engine is not runn ing.
- The auxiliary radiator fan switches on au­ tomat ically when the engine coolant
reaches a certain temperature and will
continue to run until the coolant temper ­
at ure drops.
Brake fluid
Checking brake fluid level
The brake fluid level can be checked with a
quick glance.
N N
-N
i
F ig . 2 05 Eng ine co mpartmen t: cove r on the b rake f lui d
r eservo ir
Before you check anything in th e engine com­
partment,
alwa ys read and he ed all WARN­
INGS c::> .&. in Working in the engine compart­
ment on page 2 28.
~ Read the brake fluid level from the brake
fl uid reservo ir ~
fig . 205, c::> page 230. The
brake f luid leve l must be betwee n the "M IN"
and "M AX" marki ngs.
The location of the brake fl uid reservo ir can be
see n in t he engi ne comp artment illus trati on
c::> page 230.
Checkin g and fillin g 239
The fluid level may d rop slightly afte r some
time due to the automatic adjustment of the
brake pads . T his is not cause for alarm .
If the brake flu id leve l falls considerably be­
low the "MIN" mark, the brake warning/indi­
cator light . (U.S. models) . (Canadian
models) w ill come on
~ page 14 . Do not con­
tin ue to operate the vehicle . The complete
brake sys tem should be thoroughly checked
by an authorized Audi dea ler or other quali ­
fied facility and the cause corrected.
If the
brake f lu id leve l is too low, the brake warning/
indica tor ligh t will illumi nate. Conta ct an au­
thorized Aud i de aler
immediately .
Changing brake fluid
Have the brake fluid changed by an experi­
en ced technician.
B rake fluid absorbs moisture from the air . If
the water content in the brake fluid is too
high, co rrosion in the brake system may resu lt
after a pe riod of time. The boiling point of the
brake f lu id will also dec rease conside rably and
decrease brak ing performance.
T herefo re , the bra ke fluid must be changed
every tw o year s. Always use new br ake f lu id
which con forms to Federal Mo tor Veh icle
Standard " FMVSS 116 DOT 4".
T he bra ke fluid reservo ir can be d iff icu lt to
reach, the refore, we recommend that you
have the bra ke fluid changed by your author­
ized
Audi dealer. Your dealer has the cor rect
tools, the right brake fluid and the know -how
to do this for you.
A WARNING
---- Brake flu id is poisonous. It must be stor­
ed only in the closed or iginal container
out of the reach of children!
- Brake failure can resu lt from old or inap­
prop riate brake f lu id. Observe these pre­
cautions:
- U se only brake fluid tha t meets SAE
specificat ion
J 1703 and conforms to
Federa l Motor Vehicle Standard 116.