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Engine Cooling System (H4SO) (except Sti) Subaru Impreza WRX STI GR

Cooling System (mechanical) 34 illustrations ~2473 words

SPECIFICATION

Cooling systemElectric fan + Forced engine coolant circulation system
Total engine coolant capacityL (US qt, lmp qt)AT model: Approx. 6.7 (7.1,5.9)
MT model: Approx. 6.8 (7.2, 6.0)
Water pumpTypeCentrifugal impeller type
Discharge performance IDischarge rateL (Ug gal, lmp gal)/min20 (5.3,4.4)
Pump speed - Discharge pressure760 RPM - 2.9 kPa (0.3 mAq)
Engine coolant temperature80°C (176°F)
Discharge performance IIDischargeL (US gal) lmp gal)/min100 (26.4, 22.0)
Pump speed - Discharge pressure3,000 RPM - 49 kPa (5.0 mAq)
Engine coolant temperature80°C (176°F)
Discharge performance IIIDischargeL (US gal, lmp gal)/min.200 (52.8, 44.0)
Pump speed - Discharge pressure6,000 RPM - 225.4 kPa (23 mAq)
Engine coolant temperature80°C (176°F)
Impeller diameterMm (in)76 (2.99)
Number of impeller vanes8
Pump pulley diameterMm (in)60 (2.36)
Clearance between impeller and caseStandardMm (in)0.5 - 1.5 (0.020 - 0.060)
ThermostatTypeWax pellet type
Starting temperature to open80 -84°C(176 - 183°F)
Fully opens95°C (203°F)
Valve liftMm (in)9.0 (0.354) or more
Valve boreMm (in)35(1.38)
Radiator fanMotor inputMain fan90 W
Sub fan90 W
Fan diameter/BladeMain fan300 mm (11.81 in)/4
Sub fan300 mm (11.81 in)/5
RadiatorTypeDown flow, pressure type
Core dimensionsWidth x Height x ThicknessMm (in)687.4 x 340 x 16 (27.06 x 13.39 x 0.63)
Pressure range in which cap 2 valve is openKPa (kg/cm 2 , psi)Above: 108±14.7 (1.1±0.15,16±2.1)
Below: -1.0 - -4.9 (-0.01 - -0.05, -0.1 - -0.7)
FinsCorrugated fin type
Reservoir tankCapacityL (US qt, lmp qt)0.45 (0.48, 0.40)

SPECIFICATION CHART

Recommended materialsItem numberAlternative
CoolantSUBARU SUPER COOLANT (Concentrated type)
SUBARU SUPER COOLANT (Diluted type)K0670Y0000
Water for dilutionDistilled waterSoft water or tap water
Cooling system protective agentCooling system conditionerS0A345001

COOLANT SPECIFICATION

Scheme 36

Scheme 36: WATER PUMP
Scheme 36: WATER PUMP

Tightening torque: N.m (kgf-m, ft-lb)

T1: First 12 (1.2, 8.9)

Second 12 (1.2, 8.9)

T2: 12 (1.2, 8.9)

Scheme 37

Scheme 37: RADIATOR&RADIATOR FAN
Scheme 37: RADIATOR&RADIATOR FAN

Tightening torque: N.m (kgf-m, ft-lb)

T1. 5 (0.5, 3.7)

T2: 7.5 (0.8, 5.5)

T3: 12 (13, 8.9)

T4: 3.4 (0.3, 2.5)

T5

3 (0.3, 2.2)

CAUTION

  1. Wear appropriate work clothing, including a cap, protective goggles and protective shoes when performing any work.
  2. Remove contamination including dirt and corrosion before removal, installation or disassembly.
  3. Keep the disassembled parts in order and protect them from dust and dirt.
  4. Before removal, installation or disassembly, be sure to clarify the failure. Avoid unnecessary removal, installation, disassembly and replacement.
  5. Vehicle components are extremely hot after driving. Be wary of receiving burns from heated parts.
  6. Be sure to tighten fasteners including bolts and nuts to the specified torque.
  7. Place shop jacks or rigid racks at the specified points.
  8. Before disconnecting connectors of sensors or units, be sure to disconnect the ground cable from battery.
  9. Prepare a container and cloth to prevent scattering of engine coolant when performing work where engine coolant can be spilled. If the oil spills, wipe it off immediately to prevent from penetrating into floor or flowing out for environmental protection.
  10. Follow all government and local regulations concerning disposal of refuse when disposing engine coolant.

SPECIAL TOOL

SPECIAL TOOL DESCRIPTION ILLUSTRATION TOOL NUMBER DESCRIPTION REMARKS 499977100 CRANK PULLEY WRENCH Used to stop rotation of the crank pulley when loosening or tightening crank pulley bolts. (MT model) 499977400 CRANK PULLEY WRENCH Used to stop rotation of the crank pulley when loosening or tightening crank pulley bolts. (AT model) 18231AA010 CAM SPROCKET WRENCH Used for removing and installing cam sprocket. CAM SPROCKET WRENCH (499207100) can also be used. 1B022XU0 SUBARU SELECT MONITOR III KIT Used for troubleshooting the electrical system

Scheme 38

Scheme 38: SPECIAL TOOL
Scheme 38: SPECIAL TOOL

Scheme 39

Scheme 39
Scheme 39

Scheme 40

Scheme 40
Scheme 40

GENERAL TOOL

TOOL NAMEREMARKS
Circuit testerUsed for measuring resistance and voltage.
Radiator cap testerUsed for checking radiator and radiator cap.

GENERAL TOOL DESCRIPTION

Scheme 41

Scheme 41: WIRING DIAGRAM
Scheme 41: WIRING DIAGRAM

OPERATING CONDITION

Vehicle speedA/C compressor loadEngine coolant temperature
Increase: 95°C (203°F) or less Decrease: 92°C (198°F) or lessIncrease: 96 - 99°C (205 - 210°F) Decrease: 93 - 94°C (199 - 201 °F)Increase: 100°C (212°F) or more Decrease: 95°C (203°F) or more
Radiator fan operationRadiator fan operationRadiator fan operation
During acceleration: 19 km/h (12 MPH) or less During deceleration: 10 km/h (6 MPH) or lessOFFOFFLow-SpeedHigh-Speed
LowLow-SpeedLow-SpeedHigh-Speed
HighHigh-SpeedHigh-SpeedHigh-Speed
During acceleration: 20 - 69 km/h (12 - 43 MPH) During deceleration: 11 - 64 km/h (7 - 40 MPH)OFFOFFLow-SpeedHigh-Speed
LowHigh-SpeedHigh-SpeedHigh-Speed
HighHigh-SpeedHigh-SpeedHigh-Speed
During acceleration: 70 - 134 km/h (43 -83 MPH) During deceleration: 65 - 129 km/h (40 - 80 MPH)OFFOFFLow-SpeedHigh-Speed
LowOFFLow-SpeedHigh-Speed
HighLow-SpeedHigh-SpeedHigh-Speed
During acceleration: 135 km/h (84 MPH) or more During deceleration: 130 km/h (81 MPH) or moreOFFOFFOFFHigh-Speed
LowOFFLow-SpeedHigh-Speed
HighOFFLow-SpeedHigh-Speed

OPERATING CONDITION REFERENCE

DIAGNOSIS

Radiator main fan and radiator sub fans do not rotate under the above operating conditions.

StepCheckYesNo
1 CHECK OPERATION OF RADIATOR FAN. Connect the delivery (test) mode connector. Turn the ignition switch to ON. Using the Subaru Select Monitor, check the forced operation of the radiator fan relay. NOTE: When performing a forced operation radiator fan relay check using the Subaru Select Monitor, the radiator main fan and radiator sub fan will repeat low speed revolution --> high speed revolution --> OFF in this order. Subaru Select Monitor Refer to COMPULSORY VALVE OPERATION CHECK MODE .Do the radiator main fans and radiator sub fans rotate at low speed?Go to step 2 .Go to step 3 .
2 CHECK OPERATION OF RADIATOR FAN. Connect the delivery (test) mode connector. Turn the ignition switch to ON. Using the Subaru Select Monitor, check the forced operation of the radiator fan relay. NOTE: When performing a forced operation radiator fan relay check using the Subaru Select Monitor, the radiator main fan and radiator sub fan will repeat low speed revolution --> high speed revolution --> OFF in this order. Subaru Select Monitor Refer to COMPULSORY VALVE OPERATION CHECK MODE .Do the radiator main fans and radiator sub fans rotate at high speed?Radiator main fan system is normal.Go to step 27 .
3 CHECK POWER SUPPLY TO SUB FAN RELAY. Turn the ignition switch to OFF. Remove the sub fan relay from the relay holder. Measure the voltage between the sub fan relay terminal and chassis ground. Connector & terminal (F27) No. 10 (+) - Chassis ground (-)Is the voltage 10 V or more?Go to step 4 .Go to step 5 .
4 CHECK POWER SUPPLY TO SUB FAN RELAY. Turn the ignition switch to ON. Measure the voltage between the sub fan relay terminal and chassis ground. Connector & terminal (F27) No. 13 (+) - Chassis ground (-)Is the voltage 10 V or more?Go to step 7 .Go to step 6 .
5 CHECK FUSE. Turn the ignition switch to OFF. Remove the fuse No. 3. Check the condition of fuse.Is the fuse blown out?Replace the fuse.Repair the power supply line.
6 CHECK FUSE. Turn the ignition switch to OFF. Remove the fuse No. 22. Check the condition of fuse.Is the fuse blown out?Replace the fuse.Repair the power supply line.
7 CHECK SUB FAN RELAY. Turn the ignition switch to OFF. Measure the resistance between sub fan relay terminals. Terminals No. 10 - No. 11Is the resistance 1 Mohms or more?Go to step 8 .Replace the sub fan relay. Refer to RELAY AND FUSE .
8 CHECK SUB FAN RELAY. Connect the battery to terminals No. 13 and No. 12 of the sub fan relay. Measure the resistance between sub fan relay terminals. Terminals No. 10 - No. 11Is the resistance less than 1 ohmsGo to step 9 .Replace the sub fan relay. Refer to RELAY AND FUSE .
9 CHECK HARNESS BETWEEN SUB FAN RELAY TERMINAL AND SUB FAN MOTOR ASSEMBLY CONNECTOR. Disconnect the connector from the sub fan motor assembly. Measure the resistance of harness between the sub fan relay terminal and sub fan motor assembly connector. Connector & terminal (F16) No. 2-(F27) No. 11Is the resistance less than 1 ohms?Go to step 10 .Repair the open circuit of harness between the sub fan relay terminal and sub fan motor assembly connector.
10 CHECK HARNESS BETWEEN SUB FAN MOTOR ASSEMBLY CONNECTOR AND MAIN FAN RELAY 2 CONNECTOR . Remove main fan relay 2 from the relay holder. Measure the resistance of harness between sub fan motor assembly connector and main fan relay 2 connector. Connector & terminal (F16) No. 1 - (F27) No. 18Is the resistance less than 1 ohms?Go to step 11 .Repair the open circuit of harness between sub fan motor assembly connector and main fan relay 2 connector.
11 CHECK POOR CONTACT. Check poor contact of sub fan motor assembly connector.Is there poor contact of sub fan motor assembly connector?Repair the poor contact of sub fan motor assembly connector.Go to step 12 .
12 CHECK SUB FAN MOTOR ASSEMBLY. Connect the battery positive (+) terminal to terminal No. 2 of the sub fan motor assembly, and the ground (-) terminal to terminal No. 1.Does the radiator sub fan rotate?Go to step 13.Replace the sub fan motor assembly. Refer to RADIATOR SUB FAN AND FAN MOTOR .
13 CHECK MAIN FAN RELAY 2. Measure the resistance of main fan relay 2. Terminals No. 21 - No. 18Is the resistance less than 1 ohms?Go to step 14 .Replace the main fan relay 2. Refer to RELAY AND FUSE .
14 CHECK HARNESS BETWEEN MAIN FAN RELAY 2 AND MAIN FAN MOTOR ASSEMBLY CONNECTOR. Disconnect the connector from the main fan motor assembly. Measure the resistance of harness between the main fan relay 2 terminal and main fan motor assembly connector. Connector & terminal (FIT) No. 2 - (F27) No. 21Is the resistance less than 1 ohms?Go to step 15.Repair the open circuit of harness between the main fan relay 2 terminal and main fan motor assembly connector.
15 CHECK MAIN FAN MOTOR ASSEMBLY AND GROUND CIRCUIT. Measure the resistance between the main fan motor assembly connector and chassis ground. Connector & terminal (F17) No. 1 - Chassis groundIs the resistance less than 5 ohms?Go to step 16 .Repair the open circuit of harness between main fan motor assembly connector and chassis ground.
16 CHECK POOR CONTACT. Check poor contact of main fan motor assembly connector.Is there poor contact of main fan motor assembly connector?Repair the poor contact of main fan motor assembly connector.Go to step 17 .
17 CHECK MAIN FAN MOTOR ASSEMBLY. Connect the battery positive (+) terminal to terminal No. 2 of the main fan motor assembly, and the ground (-) terminal to terminal No. 1.Does the radiator main fan rotate?Go to step 18.Replace the main fan motor assembly. Refer to RADIATOR MAIN FAN AND FAN MOTOR .
18 CHECK HARNESS BETWEEN SUB FAN RELAY AND ECM. Disconnect the connectors from ECM. Measure the resistance between the sub fan relay terminal and ECM connector. Connector & terminal (B136) No. 18 - (F27) No. 12Is the resistance less than 1 ohms?Go to step 19 .Repair the open circuit of harness between sub fan relay terminal and ECM.
19 CHECK POOR CONTACT. Check for poor contact of ECM connector.Is there poor contact of ECM connector?Repair the poor contact of ECM connector.Check the DTC. Repair the trouble cause. Refer to READ DIAGNOSTIC TROUBLE CODE (DTC) .
20 CHECK MAIN FAN RELAY 1. Turn the ignition switch to OFF. Remove main fan relay 1 from the main fuse box. Measure the resistance at the main fan relay 1 switch.Is the resistance 1 Mohms or more?Go to step 21 .Replace the main fan relay 1. Refer to RELAY AND FUSE .
21 CHECK MAIN FAN RELAY 1. Connect the main fan relay 1 coil side terminal to the battery. Measure the resistance between terminals at main fan relay 1 switch side.Is the resistance less than 1 ohms?Go to step 22 .Replace the main fan relay 1. Refer to RELAY AND FUSE .
22 CHECK HARNESS BETWEEN MAIN FAN RELAY 1 AND MAIN FAN MOTOR ASSEMBLY CONNECTOR. Disconnect the connector from the main fan motor assembly. Measure the resistance of harness between the main fan relay 1 terminal and main fan motor assembly connector. Connector & terminal (F17) No. 2 - (F36) No. 6Is the resistance less than 1 ohms?Go to step 23.Repair the open circuit of harness between the main fan relay 1 terminal and main fan motor assembly connector.
23 CHECK HARNESS BETWEEN MAIN FAN RELAY 1 AND ECM. Disconnect the connectors from ECM. Measure the resistance between the main fan relay 1 terminal and ECM connector. Connector & terminal (B136) No. 29 - (B143) No. 7Is the resistance less than 1 ohms?Go to step 24 .Repair the open circuit of the harness between main fan relay 1 terminal and ECM.
24 CHECK HARNESS BETWEEN MAIN FAN RELAY 2 AND ECM. Measure the resistance between the main fan relay 2 terminal and ECM connector. Connector & terminal (B136) No. 29 - (F27) No. 22Is the resistance less than 1 ohms?Go to step 25 .Repair the open circuit of the harness between main fan relay 2 terminal and ECM.
25 CHECK FUSE. Turn the ignition switch to OFF. Remove the fuse No. 2 and 26. Check the condition of fuse.Is the fuse blown out?Replace the fuse.Go to step 26 .
26 CHECK POOR CONTACT. Check for poor contact of ECM connector.Is there poor contact of ECM connector?Repair the poor contact of ECM connector.Repair the power supply circuit to the main fuse box.
27 CHECK OPERATION OF RADIATOR FAN. If the both radiator fans do not rotate at high speed in the condition of step 2, check whether the radiator sub fan is rotating.Does the radiator sub fan rotate?Go to step 20 .Go to step 28 .
28 CHECK GROUND CIRCUIT OF MAIN FAN RELAY 2. Remove the main fan relay 2 from A/C relay holder. Measure the resistance between main fan relay 2 terminal and chassis ground. Connector & terminal (F27) No. 19 - Chassis groundIs the resistance less than 1 ohms?Go to step 29 .Repair the open circuit of harness between main fan relay 2 and chassis ground.
29 CHECK POWER SUPPLY TO MAIN FAN RELAY 2. Turn the ignition switch to ON. Measure the voltage between main fan relay 2 terminal and chassis ground. Connector & terminal (F27) No. 20 (+) - Chassis ground (-)Is the voltage 10 V or more?Go to step 30 .Repair the power supply line.
30 CHECK MAIN FAN RELAY 2. Turn the ignition switch to OFF. Remove the main fan relay 2. Measure the resistance of main fan relay 2. Terminals (F27) No. 18 - (F27)No. 19Is the resistance 1 Mohms or more?Go to step 31 .Replace the main fan relay2. Refer to RELAY AND FUSE .
31 CHECK MAIN FAN RELAY 2. Connect the battery to terminals No. 20 and No. 22 of the main fan relay 2. Measure the resistance of main fan relay 2. Terminals (F27) No. 18 - (F27) No. 19Is the resistance less than 1 ohms?Go to step 23.Replace the main fan relay2. Refer to RELAY AND FUSE .
NOTE
When performing a forced operation radiator fan relay check using the Subaru Select Monitor, the radiator main fan and radiator sub fan will repeat low speed revolution --> high speed revolution --> OFF in this order. Subaru Select Monitor Refer to COMPULSORY VALVE OPERATION CHECK MODE .
NOTE
When performing a forced operation radiator fan relay check using the Subaru Select Monitor, the radiator main fan and radiator sub fan will repeat low speed revolution --> high speed revolution --> OFF in this order. Subaru Select Monitor Refer to COMPULSORY VALVE OPERATION CHECK MODE .

DIAGNOSIS PROCEDURE CHART

Scheme 42

Scheme 42: DRAINING OF ENGINE COOLANT
Scheme 42: DRAINING OF ENGINE COOLANT
  1. Set the vehicle on a lift.
  2. Lift up the vehicle.
  3. Remove the under cover RH.
  4. Remove the drain plug (A) to drain engine coolant into container. NOTE: Remove the radiator cap so that engine coolant will drain faster.
  5. Install the drain plug.
  6. Install the under cover RH.

Scheme 43

Scheme 43: FILLING OF ENGINE COOLANT
Scheme 43: FILLING OF ENGINE COOLANT
  1. Pour cooling system conditioner through the filler neck. Cooling system protective agent: Refer to "SPECIFICATION" for cooling system protective agent. Refer to «SPECIFICATION»(/subaru/impreza-wrx-sti/gr-2007-2011/remont/cooling-system-mechanical/#engine-cooling-system-h4so-except-sti__specification) , General Description .
  2. Pour engine coolant into the radiator up to the filler neck position. Recommended engine coolant: Refer to "SPECIFICATION" for recommended engine coolant. Refer to «SPECIFICATION»(/subaru/impreza-wrx-sti/gr-2007-2011/remont/cooling-system-mechanical/#engine-cooling-system-h4so-except-sti__specification) , General Description . Engine coolant level: Refer to "SPECIFICATION" for engine coolant level. Refer to «SPECIFICATION»(/subaru/impreza-wrx-sti/gr-2007-2011/remont/cooling-system-mechanical/#engine-cooling-system-h4so-except-sti__specification) , General Description . Engine coolant concentration: Refer to «ADJUSTMENT»(/subaru/impreza-wrx-sti/gr-2007-2011/remont/cooling-system-mechanical/#engine-cooling-system-h4so-except-sti) for the recommended engine coolant concentration., Engine Coolant . NOTE: The SUBARU Super Coolant contains anti-freeze and anti-rust agents, and is especially made for Subaru engines with an aluminum cylinder block. Always use SUBARU Super Coolant, since other coolant may cause corrosion.
  3. Fill engine coolant into the reservoir tank up to "FULL" level.
  4. Close the radiator cap and start the engine. Race 5 to 6 times at 3,000 RPM or less, then stop the engine. (Complete this operation within 40 seconds.)
  5. Wait for one minute after the engine stops, and open the radiator cap. If the engine coolant level drops, add engine coolant into radiator up to the filler neck position.
  6. Perform the procedures 4) and 5) again.
  7. Attach the radiator cap and reservoir tank cap properly.
  8. Start the engine and operate the heater at maximum hot position and the blower speed setting to "LO".
  9. Run the engine at 2,000 RPM or less until radiator fan starts and stops. NOTE: Be careful with the engine coolant temperature gauge to prevent overheating.
  10. Stop the engine and wait until the engine coolant temperature drops to 30°C (86°F) or less.
  11. Open the radiator cap. If the engine coolant level drops, add engine coolant into the radiator up to the filler neck position and the reservoir tank to "FULL" level.
  12. Attach the radiator cap correctly.
  13. Set the heater setting to maximum hot position and the blower speed setting to "LO" and start the engine. Perform racing at 3,000 RPM or less. If the flowing sound is heard from heater core at this time, perform the procedures from 9) again.

PROCEDURE TO ADJUST THE SUBARU SUPER COOLANT CONCENTRATION

CAUTIONUse the SUBARU Super Coolant with a 50 - 60% concentration in order to obtain maximum antifreeze and anti-rust performance.

To adjust the concentration of SUBARU Super Coolant according to temperature, find the proper SUBARU Super Coolant concentration in the table, and add dilution water to the SUBARU Super Coolant (concentrated type) until it reaches the proper dilution.

Relationship of SUBARU Super Coolant concentration and freezing temperature
SUBARU Super Coolant concentration50%55%60%
Freezing temperature36°C (-33°F)41°C (-42°F)50°C (-58°F)

SUBARU SUPER COOLANT CONCENTRATION REFERENCE

Engine coolant and diluting water

Refer to "SPECIFICATION" for recommended engine coolant and diluting water. Refer to SPECIFICATION , General Description .

Scheme 44

Scheme 44: REMOVAL
Scheme 44: REMOVAL

Scheme 45

Scheme 45
Scheme 45

Scheme 46

Scheme 46
Scheme 46
  1. Remove the radiator. Refer to «REMOVAL»(/subaru/impreza-wrx-sti/gr-2007-2011/remont/cooling-system-mechanical/#engine-cooling-system-h4so-except-sti) , Radiator .
  2. Remove the V-belts. Refer to «REMOVAL»(/subaru/impreza-wrx-sti/gr-2007-2011/remont/mechanical/#engine-mechanical-h4so-except-sti) , V-belt .
  3. Remove the crank pulley. Refer to «REMOVAL»(/subaru/impreza-wrx-sti/gr-2007-2011/remont/mechanical/#engine-mechanical-h4so-except-sti) , Crank Pulley .
  4. Remove the timing belt cover. Refer to «REMOVAL»(/subaru/impreza-wrx-sti/gr-2007-2011/remont/mechanical/#engine-mechanical-h4so-except-sti) , Timing Belt Cover .
  5. Remove the timing belt. Refer to «TIMING BELT»(/subaru/impreza-wrx-sti/gr-2007-2011/remont/mechanical/#engine-mechanical-h4so-except-sti) , REMOVAL, Timing Belt .
  6. Remove the automatic belt tension adjuster.
  7. Remove the camshaft position sensor. Refer to «REMOVAL»(/subaru/impreza-wrx-sti/gr-2007-2011/remont/fuel-system/#fuel-injection-system-h4so-except-sti) , Camshaft Position Sensor .
  8. Remove the cam sprocket LH. Refer to «REMOVAL»(/subaru/impreza-wrx-sti/gr-2007-2011/remont/mechanical/#engine-mechanical-h4so-except-sti) , Cam Sprocket .
  9. Remove the belt cover LH No. 2.
  10. Remove the tensioner bracket.
  11. Disconnect the hose from water pump.
  12. Remove the water pump.

Scheme 47

Scheme 47
Scheme 47

Scheme 48

Scheme 48: INSTALLATION
Scheme 48: INSTALLATION
  1. install the water pump onto cylinder block LH. NOTE: Use a new gasket. When installing the water pump, tighten the bolts in two stages in alphabetical sequence as shown in figure. Tightening torque: First 12 N.m (1.2 kgf-m, 8.9 ft-lb) Second 12 N.m (1.2 kgf-m, 8.9 ft-lb)
  2. Install the hose to water pump.
  3. Install the tensioner bracket. Tightening torque: 24.5 N.m (2.5 kgf-m, 18.1 ft-lb)
  4. Install the belt cover No. 2 LH. Tightening torque: 5 N.m (0.5 kgf-m, 3.7 ft-lb)
  5. Install the cam sprocket LH. Refer to «INSTALLATION»(/subaru/impreza-wrx-sti/gr-2007-2011/remont/mechanical/#engine-mechanical-h4so-except-sti) , Cam Sprocket .
  6. Install the camshaft position sensor. Refer to «INSTALLATION»(/subaru/impreza-wrx-sti/gr-2007-2011/remont/fuel-system/#fuel-injection-system-h4so-except-sti) , Camshaft Position Sensor .
  7. Install an automatic belt tension adjuster with the tension rod held by a pin. Refer to «AUTOMATIC BELT TENSION ADJUSTER ASSEMBLY AND BELT IDLER»(/subaru/impreza-wrx-sti/gr-2007-2011/remont/mechanical/#engine-mechanical-h4so-except-sti) , INSTALLATION, Timing Belt .
  8. Install the timing belt. Refer to «TIMING BELT»(/subaru/impreza-wrx-sti/gr-2007-2011/remont/mechanical/#engine-mechanical-h4so-except-sti) , INSTALLATION, Timing Belt .
  9. Install the timing belt cover. Refer to «INSTALLATION»(/subaru/impreza-wrx-sti/gr-2007-2011/remont/mechanical/#engine-mechanical-h4so-except-sti) , Timing Belt Cover .
  10. Install the crank pulley. Refer to «INSTALLATION»(/subaru/impreza-wrx-sti/gr-2007-2011/remont/mechanical/#engine-mechanical-h4so-except-sti) , Crank Pulley .
  11. Install the V-belts. Refer to «INSTALLATION»(/subaru/impreza-wrx-sti/gr-2007-2011/remont/mechanical/#engine-mechanical-h4so-except-sti) , V-belt .
  12. Install the radiator. Refer to «INSTALLATION»(/subaru/impreza-wrx-sti/gr-2007-2011/remont/cooling-system-mechanical/#engine-cooling-system-h4so-except-sti) , Radiator .

Scheme 49

Scheme 49: INSPECTION
Scheme 49: INSPECTION
  1. Check the water pump bearing for smooth rotation.
  2. Check the water pump pulley for abnormalities.
  3. Make sure the impeller is not deformed or damaged.
  4. Inspect the clearance between impeller and pump case. Clearance between impeller and pump case: Standard 0.5 - 1.5 mm (0.020 - 0.060 in)
  5. After water pump installation, check pulley shaft for engine coolant leaks or noise. If leaks or noise are noted, replace the water pump assembly.

Scheme 50

Scheme 50: REMOVAL
Scheme 50: REMOVAL
  1. Set the vehicle on a lift.
  2. Lift up the vehicle.
  3. Remove the under cover.
  4. Drain the engine coolant. Refer to «DRAINING OF ENGINE COOLANT»(/subaru/impreza-wrx-sti/gr-2007-2011/remont/cooling-system-mechanical/#engine-cooling-system-h4so-except-sti) , REPLACEMENT, Engine Coolant .
  5. Remove the front exhaust pipe. Refer to «REMOVAL»(/subaru/impreza-wrx-sti/gr-2007-2011/remont/exhaust/#exhaust-system-h4so-except-sti__removal) , Front Exhaust Pipe .
  6. Disconnect the radiator outlet hose from thermostat cover.
  7. Remove the thermostat cover, and then remove the gasket and thermostat.

Scheme 51

Scheme 51
Scheme 51

Scheme 52

Scheme 52: INSTALLATION
Scheme 52: INSTALLATION
  1. Install a gasket to thermostat. NOTE: Use a new gasket.
  2. Install the thermostat and thermostat cover. NOTE: Install 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 front exhaust pipe. Refer to «INSTALLATION»(/subaru/impreza-wrx-sti/gr-2007-2011/remont/exhaust/#exhaust-system-h4so-except-sti__installation) , Front Exhaust Pipe .
  5. Install the under cover.
  6. Lower the vehicle.
  7. Fill engine coolant. Refer to «FILLING OF ENGINE COOLANT»(/subaru/impreza-wrx-sti/gr-2007-2011/remont/cooling-system-mechanical/#engine-cooling-system-h4so-except-sti) , REPLACEMENT, Engine Coolant .

INSPECTION

Replace the thermostat if the valve does not close completely at an ambient temperature or if the following test shows unsatisfactory results.

  1. Inspection method

Immerse the thermostat and a thermometer in water. Raise water temperature gradually, and measure the temperature and valve lift when the valve begins to open and when the valve is fully opened. During the test, agitate the water for even temperature distribution. The measured value should meet the specification.

Note. Leave the thermostat in the boiling water for five minutes or more before measuring valve lift. Hold the thermostat with a wire or the like to avoid contacting the container.

Starting temperature to open

80 - 84°C (176 - 183°F)

Full open temperature

95°C (203°F)

Total valve lift

9.0 mm (0.354 in) or more

Scheme 53

Scheme 53
Scheme 53

REMOVAL

CAUTIONThe radiator is pressurized when the engine and radiator are hot. Wait until engine and radiator cool down before working on the radiator.

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Scheme 54

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Scheme 57

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Scheme 59
Scheme 59

Scheme 60

Scheme 60
Scheme 60
  1. Set the vehicle on a lift.
  2. Disconnect the ground cable from battery.
  3. Lift up the vehicle.
  4. Remove the under cover.
  5. Remove the heat shield cover from radiator. (AT model)
  6. Drain the engine coolant. Refer to «DRAINING OF ENGINE COOLANT»(/subaru/impreza-wrx-sti/gr-2007-2011/remont/cooling-system-mechanical/#engine-cooling-system-h4so-except-sti) , REPLACEMENT, Engine Coolant .
  7. Disconnect the main fan motor assembly connector (A) and sub fan motor assembly connector (B).
  8. Disconnect the radiator outlet hose from thermostat cover.
  9. Disconnect the ATF cooler hoses from ATF pipes. (AT model) NOTE: Plug the ATF pipe to prevent ATF from leaking.
  10. Lower the vehicle.
  11. Disconnect the over flow hose.
  12. Remove the reservoir tank. Refer to «REMOVAL»(/subaru/impreza-wrx-sti/gr-2007-2011/remont/cooling-system-mechanical/#engine-cooling-system-h4so-except-sti) , Reservoir Tank .
  13. Remove the air intake duct. Refer to «REMOVAL»(/subaru/impreza-wrx-sti/gr-2007-2011/remont/mechanical/#engine-intake-system-h4so-except-sti) , Air Intake Duct .
  14. Disconnect the radiator inlet hose from engine.
  15. Remove the radiator upper brackets.
  16. Lift the radiator up and remove the radiator from vehicle.

Scheme 61

Scheme 61: INSTALLATION
Scheme 61: INSTALLATION

Scheme 62

Scheme 62
Scheme 62
  1. Attach the radiator lower cushion to the hole on 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 and tighten the bolts. Tightening torque: 12 N.m (1.2 kgf-m, 8.9 ft-lb)
  4. Connect the radiator inlet hose.
  5. Install the air intake duct. Refer to «INSTALLATION»(/subaru/impreza-wrx-sti/gr-2007-2011/remont/mechanical/#engine-intake-system-h4so-except-sti) , Air Intake Duct .
  6. Install the reservoir tank. Refer to «INSTALLATION»(/subaru/impreza-wrx-sti/gr-2007-2011/remont/cooling-system-mechanical/#engine-cooling-system-h4so-except-sti) , Reservoir Tank .
  7. Connect the over flow hose.
  8. Lift up the vehicle.
  9. Connect the ATF cooler hoses. (AT model)
  10. Connect the radiator outlet hose.
  11. Connect the main fan motor assembly connector (A) and sub fan motor assembly connector (B).
  12. Install the heat shield cover. (AT model) Tightening torque: 3 N.m (0.3 kgf-m, 2.2 ft-lb)
  13. Install the under cover.
  14. Lower the vehicle.
  15. Connect the ground cable to battery.
  16. Fill engine coolant. Refer to «FILLING OF ENGINE COOLANT»(/subaru/impreza-wrx-sti/gr-2007-2011/remont/cooling-system-mechanical/#engine-cooling-system-h4so-except-sti) , REPLACEMENT, Engine Coolant .
  17. Check the ATF level. (AT model) Refer to «INSPECTION»(/subaru/impreza-wrx-sti/gr-2007-2011/remont/automatic-trans/#automatic-transmission-4at-except-sti__inspection) , Automatic Transmission Fluid .

Scheme 63

Scheme 63: INSPECTION
Scheme 63: INSPECTION
  1. Remove the radiator cap, fill the radiator with engine coolant, and then install the tester to the installation position of cap.
  2. Apply a pressure of 157 kPa (1.6 kg/cm 2 , 23 psi) to the radiator and check the following points: Leakage from the radiator or its vicinity Leakage from the hose or its connections CAUTION: Engine should be turned off. Wipe engine coolant from check points in advance. Be careful of engine coolant from spurting out when removing the tester. Be careful not to deform the filler neck of radiator when installing and removing the tester.

Scheme 64

Scheme 64: INSPECTION
Scheme 64: INSPECTION
  1. Attach the radiator cap tester to radiator cap.
  2. Increase pressure until the radiator cap tester gauge pointer stops. Radiator cap is functioning properly if it holds the service limit pressure for 5 - 6 seconds. Replace the cap if it is opened under a pressure less than the service limit value.

Standard

93 - 123 kPa (0.95 - 1.25 kg/cm 2 , 14 - 18 psi)

Service limit: 83 kPa (0.85 kg/cm 2 , 12 psi)

CAUTIONBe sure to remove foreign matter and rust from the cap in advance. Otherwise, results of pressure test will be incorrect.

Scheme 65

Scheme 65
Scheme 65

Scheme 66

Scheme 66
Scheme 66
  1. Set the vehicle on a lift.
  2. Disconnect the ground cable from battery.
  3. Lift up the vehicle.
  4. Remove the under cover.
  5. Disconnect the connector (A) of the main fan motor assembly.
  6. Remove the heat shield cover. (AT model)
  7. Remove the ATF hose from the clip of the radiator main fan shroud. (AT model)
  8. Lower the vehicle.
  9. Drain approximately 2.0 l of coolant. Refer to «DRAINING OF ENGINE COOLANT»(/subaru/impreza-wrx-sti/gr-2007-2011/remont/cooling-system-mechanical/#engine-cooling-system-h4so-except-sti) , REPLACEMENT, Engine Coolant .
  10. Disconnect the radiator inlet hose from engine side.
  11. Disconnect the over flow hose.
  12. Remove the reservoir tank. Refer to «REMOVAL»(/subaru/impreza-wrx-sti/gr-2007-2011/remont/cooling-system-mechanical/#engine-cooling-system-h4so-except-sti) , Reservoir Tank .
  13. Remove the bolts which hold the radiator main fan shroud onto the radiator.
  14. Remove the radiator main fan and fan motor.

INSTALLATION

Install in the reverse order of removal.

CAUTIONCheck if the radiator hose and the over flow hose are properly connected.

Note. If the installation of the radiator main fan and fan motor is difficult, attempt installation after loosening the bolts which hold the radiator sub fan shroud to the radiator.

Tightening torque

7.5 N.m (0.8 kgf-m, 5.5 ft-lb)

Tightening torque

3 N.m (0.3 kgf-m, 2.2 ft-lb)

DISASSEMBLY

  1. Remove the clip which holds the main fan motor assembly connector onto the radiator main fan shroud.
  2. Remove the bolts which hold the main fan motor assembly onto the radiator main fan shroud.

Scheme 67

Scheme 67
Scheme 67

ASSEMBLY

Assemble in the reverse order of disassembly.

Tightening torque

5 N.m (0.5 kgf-m, 3.7 ft-lb)

Scheme 68

Scheme 68
Scheme 68
  1. Set the vehicle on a lift.
  2. Disconnect the ground cable from battery.
  3. Lift up the vehicle.
  4. Remove the under cover.
  5. Remove the connector (B) of sub fan motor assembly.
  6. Remove the heat shield cover. (AT model)
  7. Remove the ATF hose from the clip of the radiator sub fan shroud. (AT model)
  8. Lower the vehicle.
  9. Remove the air intake duct. Refer to «REMOVAL»(/subaru/impreza-wrx-sti/gr-2007-2011/remont/mechanical/#engine-intake-system-h4so-except-sti) , Air Intake Duct .
  10. Drain approximately 2.0 l of coolant. Refer to «DRAINING OF ENGINE COOLANT»(/subaru/impreza-wrx-sti/gr-2007-2011/remont/cooling-system-mechanical/#engine-cooling-system-h4so-except-sti) , REPLACEMENT, Engine Coolant .
  11. Disconnect the radiator inlet hose from engine side.
  12. Remove the bolts which hold the radiator sub fan shroud onto the radiator.
  13. Remove the radiator sub fan and fan motor.
CAUTIONConfirm that the radiator hose is securely connected.

Install in the reverse order of removal.

Tightening torque

7.5 N.m (0.8 kgf-m, 5.5 ft-lb)

Tightening torque

3 N.m (0.3 kgf-m, 2.2 lb)

  1. Remove the clip which holds the sub fan motor assembly connector onto the radiator sub fan shroud.
  2. Remove the bolts which hold the sub fan motor assembly onto the radiator sub fan shroud.

Assemble in the reverse order of disassembly.

Tightening torque

5 N.m (0.5 kgf-m, 3.7 ft-lb)

  1. Disconnect the over flow hose connected to the radiator filler neck.
  2. Push in the hook (A), and pull the reserve tank in the direction of the arrow to remove.

Scheme 69

Scheme 69
Scheme 69

Install in the reverse order of removal.

Make sure the engine coolant level is between "FULL" and "LOW".

TroublePossible causeCorrective action
Over-heatingA. Insufficient engine coolantReplenish engine coolant, inspect for leakage, and repair it if necessary.
B. Loose timing beltRepair or replace timing belt tensioner.
C. Oil on timing beltReplace.
D. Malfunction of thermostatReplace.
E. Malfunction of water pumpReplace.
F. Clogged engine coolant passageClean.
G. Improper ignition timingInspect and repair ignition control system. Refer to BASIC DIAGNOSTIC PROCEDURE .
H. Clogged or leaking radiatorClean, repair or replace.
I. Defective radiator fanReplace.
J. Improper engine oil in engine coolantReplace the engine coolant. If ineffective, check, repair or replace engine components.
K. Air/fuel mixture ratio too leanInspect and repair the fuel injection system. Refer to BASIC DIAGNOSTIC PROCEDURE .
I. Excessive back pressure in exhaust systemClean or replace.
M. Insufficient clearance between piston and cylinderAdjust or replace.
N. Slipping clutchRepair or replace.
O. Dragging brakeAdjust.
P. Defective radiator fanInspect the radiator fan relay, engine coolant temperature sensor or fan motor assembly and replace them.
Over-coolingA. Ambient temperature extremely lowPartly cover radiator front area.
B. Defective thermostatReplace.
Engine coolant leaksA. Loosened or damaged connecting units on hosesRepair or replace.
B. Leakage from water pumpReplace.
C. Leakage from water pipeRepair or replace.
D. Leakage around cylinder head gasketRetighten cylinder head bolts or replace cylinder head gasket.
E. Damaged or cracked cylinder head and cylinder blockRepair or replace.
F. Damaged or cracked thermostat coverRepair or replace.
G. Leakage from radiatorRepair or replace.
NoiseA. Timing belt problemReplace.
B. Defective radiator fanReplace.
C. Defective water pump bearingReplace water pump.
D. Defective water pump mechanical sealReplace water pump.

ENGINE COOLING SYSTEM TROUBLE REFERENCE

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