engine SUBARU IMPREZA WRX STI 2011 Owners Manual

Black plate (376,1)
北米Model "A1110BE-C" EDITED: 2010/ 12/ 17
11-16
Maintenance and service
4. Install the under cover.Non-turbo models
1) Fill up to this levelTurbo models
1) Fill up to this level5. Slowly pour the coolant and fill up to just below the filler neck, allowing enough
room to add genuine SUBARU cooling
system conditioner in the radiator. Add
genuine SUBARU cooling system condi-
tioner until the coolant level reaches the
filler neck. Do not pour the coolant too
quickly, as this may lead to insufficient air
bleeding and trapped air in the system.
NOTEFor the guidelines of coolant quantity
(including coolant in the reservoir
tank), refer to
“Engine coolant ”F12-
10.1) “FULL ”level mark
2) “LOW ”level mark
CAUTION
. Be careful not to spill engine
coolant when adding it. If coolant
touches the exhaust pipe, it may
cause a bad smell, smoke, and/or
a fire. If engine coolant gets on
the exhaust pipe, be sure to wipe
it off.
. Do not splash the engine coolant
over painted parts. The alcohol
contained in the engine coolant
may damage the paint surface.
6. Pour the coolant and fill to the reser-
voir tank ’s “FULL ”level mark.7. Put the radiator cap back on and
tighten firmly. At this time, make sure that
the rubber gasket in the radiator cap is

Black plate (377,1)
北米Model "A1110BE-C" EDITED: 2010/ 12/ 17
correctly in place.
8. Start and race the engine at 2,000 to
3,000 rpm for 5 to 6 times within 40
seconds.
9. Stop the engine and wait until the
coolant cools down (122 to 140 8F [50 to
60 8C]). If there is any loss of coolant, add
coolant to the radiator ’s filler neck and to
the reserve tank ’s “FULL ”level.
10. Put the radiator cap and reservoir cap
back on and tighten firmly.
Air cleaner element
WARNING
Do not operate the engine with the
air cleaner element removed. The air
cleaner element not only filters
intake air but also stops flames if
the engine backfires. If the air
cleaner element is not installed
when the engine backfires, you
could be burned.
CAUTION
When replacing the air cleaner ele-
ment, use a genuine SUBARU air
cleaner element. If it is not used,
there is the possibility of causing a
negative effect to the engine.
The air cleaner element functions as a
filter screen. When the element is perfo-
rated or removed, engine wear will be
excessive and engine life shortened.
It is not necessary to clean or wash the air
cleaner element.
& Replacing the air cleaner
elementReplace the air cleaner element according
to the maintenance schedule in the
“Warranty and Maintenance Booklet ”. Un-
der extremely dusty conditions, replace it
more frequently. It is recommended that
you always use genuine SUBARU parts.
! Non-turbo models1) Connector
2) Clip
3) Clamp
4) Air intake boot
5) Clip1. Unplug the connector that is attached
to the top of the air cleaner case.
2. Detach the connector cable from the
clip on the right side on the air cleaner
Maintenance and service
11-17
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11

Black plate (380,1)
北米Model "A1110BE-C" EDITED: 2010/ 12/ 17
11-20
Maintenance and service
& Recommended spark plugsFor the recommended spark plugs, refer
to“Electrical system ”F 12-3.
Drive belts1) Power steering oil pump pulley
2) Front side belt
3) Alternator pulley
4) Air conditioner compressor pulley
5) Rear side belt
6) Crank pulley
A) 22 lbf (98 N, 10 kgf)
CAUTION
The front side belt, which runs in
conjunction with the following com-
ponents, must be used within the
specified deflection.
. Power steering oil pump pulley
. Alternator pulley
. Crank pulley Check the deflection of the front
side belt and if there is any loosen-
ess, cracks, wear or unusual noise
on the front side belt, contact your
SUBARU dealer.
Continuing to use the vehicle with
the belt outside of the specification
may cause the engine to malfunc-
tion and the above components to
malfunction.
To check the deflection of the front side
belt, place a straightedge (ruler) across
two adjacent pulleys (alternator pulley and
crank pulley) and apply a force of 22 lbf
(98 N, 10 kgf) midway between the pulleys
by using a spring scale. The belt deflec-
tion should be the amount specified. If the
front side belt is loose, cracked or worn,
contact your SUBARU dealer.
in (mm)
Deflection
New belt Used belt
A 0.28
–0.35
(7.0 –9.0) 0.35
–0.43
(9.0 –11.0)
The rear side belt is a stretch-type belt,
therefore the deflection does not need to
be checked. If there are cracks or wear
confirmed on the belts and a squeaking
noise is heard from them, contact your
SUBARU dealer.

Black plate (381,1)
北米Model "A1110BE-C" EDITED: 2010/ 12/ 17
Manual transmission oil& Checking the oil levelNon-turbo models
1) Yellow handleTurbo models except STI
Check the oil level monthly.
1. Park the vehicle on a level surface and
stop the engine.
2. Pull out the level gauge, wipe it clean,
and insert it again.1) Upper level
2) Lower level3. Pull out the level gauge again and
check the oil level on it. If it is below the
lower level, add oil through the level
gauge hole to bring the level up to the
upper level.
CAUTION
Be careful not to spill manual trans-
mission oil when adding it. If oil
touches the exhaust pipe, it may
cause a bad smell, smoke, and/or a
fire. If oil gets on the exhaust pipe,
be sure to wipe it off.NOTEThere is no transmission oil level
gauge for STI. Consult your SUBARU
dealer to check the oil level.&Recommended grade and
viscosityEach oil manufacturer has its own base
oils and additives. Never use different
brands together. For details, refer to
“Manual transmission, front differential
and rear differential gear oil ”F 12-8.
Maintenance and service
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Black plate (382,1)
北米Model "A1110BE-C" EDITED: 2010/ 12/ 17
11-22
Maintenance and service
Automatic transmission fluid& Checking the fluid levelThe automatic transmission fluid expands
largely as its temperature rises; the fluid
level differs according to fluid temperature.
Therefore, there are two different scales
for checking the level of hot fluid and cold
fluid on the level gauge.
Though the fluid level can be checked
without warming up the fluid on the
“COLD ”range, it is recommended to
check the fluid level when the fluid is at
operating temperature.
! Checking the fluid level when the
fluid is hot
1. Drive the vehicle several miles to raise
the temperature of the transmission fluid
up to normal operating temperature; 158
to 176 8F (70 to 80 8C) is normal.
2. Park the vehicle on a level surface and
set the parking brake.
3. First shift the select lever in each
position. Then shift it in the “P”position,
and run the engine at idling speed.
1) Yellow handle1) HOT range
2) COLD range
3) Upper level
4) Lower level4. Pull out the level gauge and check the fluid level on the gauge. If it is below the
lower level on the
“HOT”range, add the
recommended automatic transmission
fluid up to the upper level.
! Checking the fluid level when the
fluid is cold
When the fluid level has to be checked
without time to warm up the automatic
transmission, check to see that the fluid
level is between the lower level and upper
level on the “COLD”range. If it is below
that range, add fluid up to the upper level.
Be careful not to overfill.
CAUTION
Be careful not to spill automatic
transmission fluid when adding it.
If automatic transmission fluid
touches the exhaust pipe, it may
cause a bad smell, smoke, and/or a
fire. If automatic transmission fluid
gets on the exhaust pipe, be sure to
wipe it off.

Black plate (383,1)
北米Model "A1110BE-C" EDITED: 2010/ 12/ 17
& Recommended fluidRefer to “Fluids”F 12-9.NOTEFor optimum transmission perfor-
mance, only use the automatic trans-
mission fluid that is recommended and
provided by SUBARU.
If the recommended automatic trans-
mission fluid is unavailable, Dexron III
may be temporarily used. If the Dexron
III is used continuously there will be a
noticeable increase in the vibration and
noise from the automatic transmission.
Front differential gear oil (AT
models)& Checking the oil level1) Yellow handle1. Park the vehicle on a level surface and
stop the engine.
2. Pull out the level gauge, wipe it clean,
and insert it again.
1) Upper level
2) Lower level3. Pull out the level gauge again and
check the oil level on it. If it is below the
lower level, add oil to bring the level up to
the upper level.
CAUTION
Be careful not to spill front differ-
ential gear oil when adding it. If oil
touches the exhaust pipe, it may
cause a bad smell, smoke, and/or a
fire. If oil gets on the exhaust pipe,
be sure to wipe it off.
Maintenance and service
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11

Black plate (384,1)
北米Model "A1110BE-C" EDITED: 2010/ 12/ 17
11-24
Maintenance and service
& Recommended grade and
viscosityEach oil manufacturer has its own base
oils and additives. Never use different
brands together. For details, refer to
“Manual transmission, front differential
and rear differential gear oil ”F 12-8.
Rear differential gear oilThere is no rear differential gear oil level
gauge. To check the rear differential gear
oil level, we recommend that you consult
your SUBARU dealer for inspection.& Recommended grade and
viscosityEach oil manufacturer has its own base
oils and additives. Never use different
brands together. For details, refer to
“Manual transmission, front differential
and rear differential gear oil ”F 12-8.
Power steering fluid& Checking the fluid levelThe power steering fluid expands greatly
as its temperature rises; the fluid level
differs according to fluid temperature.
Therefore, the reservoir tank has two
different checking ranges for hot and cold
fluids.
Check the power steering fluid level
monthly.
1. Park the vehicle on a level surface,
and stop the engine.

Black plate (387,1)
北米Model "A1110BE-C" EDITED: 2010/ 12/ 17
advisable.
CAUTION
. Clutch fluid absorbs moisture
from the air. Any absorbed moist-
ure can cause improper clutch
operation.
. If the vehicle requires frequent
refilling, there may be a leak. If
you suspect a problem, have the
vehicle checked at your SUBARU
dealer.
. When clutch fluid is added, be
careful not to allow any dirt into
the tank.
. Never splash the clutch fluid over
painted surfaces or rubber parts.
Alcohol contained in the clutch
fluid may damage them.
. Be careful not to spill clutch fluid
when adding it. If clutch fluid
touches the exhaust pipe, it may
cause a bad smell, smoke, and/or
a fire. If clutch fluid gets on the
exhaust pipe, be sure to wipe it
off.
& Recommended clutch fluidRefer to “Fluids”F 12-9.
CAUTION
Never use different brands of clutch
fluid together. Also, avoid mixing
DOT 3 and DOT 4 brake fluids even if
they are the same brand.
Brake boosterIf the brake booster does not operate as
described in the following, have it checked
by your SUBARU dealer.
1. With the engine off, depress the brake
pedal several times, applying the same
pedal force each time. The distance the
pedal travels should not vary.
2. With the brake pedal depressed, start
the engine. The pedal should move
slightly down to the floor.
3. With the brake pedal depressed, stop
the engine and keep the pedal depressed
for 30 seconds. The pedal height should
not change.
4. Start the engine again and run for
approximately one minute then turn it off.
Depress the brake pedal several times to
check the brake booster. The brake
booster operates properly if the pedal
stroke decreases with each depression.NOTEFor vehicles equipped with the brake
assist system, when you depress the
brake pedal strongly or suddenly, the
following phenomena occur. However,
even though these occur, they do not
indicate any malfunctions, and the
brake assist system is operating prop-
Maintenance and service
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Black plate (388,1)
北米Model "A1110BE-C" EDITED: 2010/ 12/ 17
11-28
Maintenance and service
erly.
. You might feel that the brake pedal
is applied by lighter force and gener-
ates a greater braking force.
. You might hear clicking (knocking)
sounds around brake pedal.
Brake assist is not a system that brings
more braking ability to the vehicle
beyond its breaking capability.
Brake pedalCheck the brake pedal free play and
reserve distance according to the main-
tenance schedule in the “Warranty and
Maintenance Booklet ”.&Checking the brake pedal
free play1) 0.02 –0.08 in (0.5 –2.0 mm)Stop the engine and firmly depress the
brake pedal several times. Lightly pull the
brake pedal up with one finger to check
the free play with a force of less than 2 lbf
(10 N, 1 kgf).
If the free play is not within proper
specification, contact your SUBARU deal-
er.
& Checking the brake pedal
reserve distance1) More than 2.56 in (65 mm)Depress the pedal with a force of approxi-
mately 66 lbf (294 N, 30 kgf) and measure
the distance between the upper surface of
the pedal pad and the floor.
When the measurement is smaller than
the specification, or when the pedal does
not operate smoothly, contact with your
SUBARU dealer.

Black plate (389,1)
北米Model "A1110BE-C" EDITED: 2010/ 12/ 17
Clutch pedal (MT models)Check the clutch pedal free play and
reserve distance according to the main-
tenance schedule in the “Warranty and
Maintenance Booklet ”.&Checking the clutch functionCheck the clutch engagement and disen-
gagement.
1. With the engine idling, check that there
are no abnormal noises when the clutch
pedal is depressed, and that shifting into
1st or reverse feels smooth.
2. Start the vehicle by releasing the pedal
slowly to check that the engine and
transmission smoothly couple without
any sign of slippage.
&Checking the clutch pedal
free play1) 0.16 –0.43 in (4.0 –11.0 mm)Lightly depress the clutch pedal down with
your finger until you feel resistance, and
check the free play.
If the free play is not within proper
specification, contact your SUBARU deal-
er.
Hill start assist system (MT
models –if equipped)Ensure that the Hill start assist system
operates properly under the following
circumstances:
1. Stop the vehicle on an uphill grade by
depressing the brake pedal and clutch
pedal, with the engine running.
2. Make sure that the vehicle does not
move backward even after the brake
pedal is released.
3. Then make sure the vehicle starts
climbing the grade by following the normal
starting procedures.
If the Hill start assist system does not
operate as described above, contact with
your SUBARU dealer.
Maintenance and service
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