Subaru Impreza 3 / Impreza WRX / Impreza WRX STI. Manual - part 187

CO(w/o STI)-17

Thermostat

COOLING

5. Thermostat

A: REMOVAL

1) Lift up the vehicle.

2) Remove  the  under  cover.  <Ref.  to  EI-28,  RE-

MOVAL, Front Under Cover.>

3) Drain engine coolant. <Ref. to CO(w/o STI)-13,

DRAINING  OF  ENGINE  COOLANT,  REPLACE-

MENT, Engine Coolant.>

4) Disconnect the radiator outlet hose from thermo-

stat cover.

5) Remove the thermostat cover, and then remove

the gasket and thermostat.

B: INSTALLATION

1) Install a gasket to thermostat.
NOTE:

Use a new gasket.

2) Install the thermostat and thermostat cover.
NOTE:

Install the parts with the jiggle pin facing upward.
Tightening torque:

12 N·m (1.2 kgf-m, 8.9 ft-lb)

3) Connect  the  radiator  outlet  hose  to  thermostat

cover.

4) Install the under cover. <Ref. to EI-28, INSTAL-

LATION, Front Under Cover.>

5) Lower the vehicle.

6) Fill  engine  coolant.  <Ref.  to  CO(w/o  STI)-13,

FILLING  OF  ENGINE  COOLANT,  REPLACE-

MENT, Engine Coolant.>

(A) Thermostat cover
(B) Gasket

(C) Thermostat

CO-02771

CO-02780

(B)

(A)

(C)

(A) Thermostat cover
(B) Gasket

(C) Thermostat
(D) Jiggle pin

CO-02781

(B)

(A)

(C)

(D)

CO(w/o STI)-18

Thermostat

COOLING

C: INSPECTION

1) Check that the thermostat does not have defor-

mation, cracks or damage.

2) Check  that  the  thermostat  valve  closes  com-

pletely at an ambient temperature.

3) Immerse  the  thermostat  and  a  thermometer  in

water.  Raise  water  temperature  gradually,  and

check the temperature and valve lift when the valve

begins to open and when the valve is fully opened.

Replace the thermostat if faulty.
NOTE:

• During the test, agitate the water for even tem-

perature distribution.

• Leave the thermostat in the boiling water for five

minutes or more before measuring the valve lift.

• Hold  the  thermostat  with  a  wire  or  the  like  to

avoid contacting the container.
Starting temperature to open:

76 — 80°C (169 — 176°F)

Full open temperature:

91°C (196°F)

Total valve lift:

9.0 mm (0.354 in) or more

(A) Thermometer
(B) Thermostat

CO-02420

(A)

(B)

CO(w/o STI)-19

Radiator

COOLING

6. Radiator

A: REMOVAL

CAUTION:

The  radiator  is  pressurized  when  the  engine

and radiator are hot. Wait until engine and radi-

ator cool down before working on the radiator.

1) Disconnect the ground cable from battery.

2) Lift up the vehicle.

3) Remove  the  under  cover.  <Ref.  to  EI-28,  RE-

MOVAL, Front Under Cover.>

4) Drain engine coolant. <Ref. to CO(w/o STI)-13,

DRAINING  OF  ENGINE  COOLANT,  REPLACE-

MENT, Engine Coolant.>

5) Disconnect the connector (A) from the main fan

motor and the connector (B) from the sub fan mo-

tor.

6) Disconnect the radiator outlet hose from thermo-

stat cover.

7) Lower the vehicle.

8) Remove the air intake duct. <Ref. to IN(w/o STI)-

10, REMOVAL, Air Intake Duct.>

9) Remove  the  reservoir  tank.  <Ref.  to  CO(w/o

STI)-27, REMOVAL, Reservoir Tank.>

10) Disconnect the radiator inlet hose from the ra-

diator.

11) Disconnect the two engine coolant hoses from

the radiator and over flow pipe.

12) Remove the radiator upper brackets.

IN-00203

(A)

CO-02727

(B)

CO-02728

CO-02771

CO-02712

CO-02713

CO-02370

CO(w/o STI)-20

Radiator

COOLING

13) Move the radiator to the left while lifting it up-

ward.

14) Lift  the  radiator  up  and  remove  the  radiator

from vehicle.

15) Remove the radiator lower cushion from the ra-

diator lower bracket.

B: INSTALLATION

1) Attach the radiator lower cushion to the radiator

lower bracket.

2) Install the radiator to vehicle.
NOTE:

Make pins on the lower side of radiator be fitted into

the radiator lower cushions.

3) Install the radiator upper brackets.
Tightening torque:

12 N·m (1.2 kgf-m, 8.9 ft-lb)

4) Connect the two engine coolant hoses to the ra-

diator and over flow pipe.

5) Connect the radiator inlet hose.

6) Install the reservoir tank. <Ref. to CO(w/o STI)-

27, INSTALLATION, Reservoir Tank.>

7) Install the air intake duct. <Ref. to IN(w/o STI)-

10, INSTALLATION, Air Intake Duct.>

8) Lift up the vehicle.

9) Connect the radiator outlet hose.

CO-02729

CO-02729

CO-02370

CO-02713

CO-02712

CO-02771