Engine Mecahnical - 2.5l - SOHC Subaru Impreza WRX GD/GG рестайлинг

SPECIFICATIONS

Note. US: Undersize OS: Oversize

Engine Specifications

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CAUTION

1. Wear working clothing, including a cap, protective goggles, and protective shoes during operation.
2. Remove contamination including dirt and corrosion before removal, installation or disassembly.
3. Keep the disassembled parts in order and protect them from dust or dirt.
4. Before removal, installation or disassembly, be sure to clarify the failure. Avoid unnecessary removal, installation, disassembly, and replacement.
5. Be careful not to burn your hands, because each part on the vehicle is hot after running.
6. Be sure to tighten fasteners including bolts and nuts to the specified torque.
7. Place shop jacks or safety stands at the specified points.
8. Before disconnecting electrical connectors of sensors or units, be sure to disconnect the ground cable from battery.
9. All parts should be thoroughly cleaned, paying special attention to the engine oil passages, pistons and bearings.
10. Rotating parts and sliding parts such as piston, bearing and gear should be coated with oil prior to assembly.
11. Be careful not to let oil, grease or coolant contact the timing belt, clutch disc and flywheel.
12. All removed parts, if to be reused, should be re-installed in the original positions and directions.
13. Bolts, nuts and washers should be replaced with new ones as required.
14. Even if necessary inspections have been made in advance, proceed with assembly work while making rechecks.
15. Remove or install engine in an area where chain hoists, lifting devices, etc. are available for ready use.
16. Be sure not to damage coated surfaces of body panels with tools or stain seats and windows with coolant or oil. Place a cover over fenders, as required, for protection.
17. Prior to starting work, prepare the following: Service tools, clean cloth, containers to catch coolant and oil, wire ropes, chain hoist, transmission jacks, etc.
18. Lift-up or lower the vehicle when necessary. Make sure to support the correct positions.

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GENERAL PURPOSE TOOLS

GENERAL PURPOSE TOOLS

PROCEDURE

It is possible to conduct the following service procedures with engine on the vehicle, however, the procedures described in this section are based on the condition that the engine is removed from the vehicle.

1. V-belt
2. Timing belt
3. Valve rocker assembly
4. Camshaft
5. Cylinder head

INSPECTION

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1. After warming-up the engine, turn the ignition switch to OFF.
2. Make sure that the battery is fully charged.
3. Lower the fuel pressure, see «FUEL SYSTEM PRESSURE RELEASE»(/subaru/impreza-wrx/gdgg-2002-2005/remont/removal-installation/#engine-controls-removal-installation-impreza-outback-sport__fuel-system-pressure-release) , Fuel.
4. Remove all the spark plugs, see «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/ignition-system/#ignition-system-sohc__removal) , Spark Plug.
5. Throttle valve should be wide open.
6. Check the starter motor for satisfactory performance and operation.
7. Hold the compression gauge tight against spark plug hole. NOTE: When using a screw-in type compression gauge, the screw (put into cylinder head spark plug hole) should be shorter than 18 mm (0.71 in).
8. Crank the engine by means of starter motor, and then read the maximum value on the gauge when the pointer is steady.
9. Take at least two measurements per cylinder, and make sure that the values are correct. Compression (350 RPM at wide open throttle): Standard; 1,275 kPa (13.0 kgf/cm 2 , 185 psi) Limit; 1,079 kPa (11.0 kgf/cm 2 , 148 psi) Difference between cylinders; 49 kPa (0.5 kgf/cm 2 , 7 psi), or less

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1. Before checking idle speed, check the following: Ensure the air cleaner element is free from clogging, ignition timing is correct, spark plugs are in good condition, and the hoses are connected properly. Ensure the CHECK ENGINE malfunction indicator light does not illuminate.
2. Warm up the engine.
3. Stop the engine, and then turn the ignition switch to OFF.
4. When using the SUBARU SELECT MONITOR. See «SPECIAL TOOLS»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , PREPARATION TOOL, General Description. Insert the cartridge to SUBARU SELECT MONITOR. Connect the SUBARU SELECT MONITOR to data link connector. Turn the ignition switch to ON, and SUBARU SELECT MONITOR switch to ON. Select {2. Each System Check} in Main Menu. Select {Engine Control System} in Selection Menu. Select {1. Current Data Display & Save} in Engine Control System Diagnosis. Select {1.12 Data Display} in Data Display Menu. Start the engine, and then read the engine idle speed.
5. When using the tachometer (secondary pick-up type). Attach the pick-up clip to No. 1 cylinder spark plug cord. Start the engine, and then read the engine idle speed. NOTE: When using an OBD-II general scan tool, carefully read its operation manual. This ignition system provides simultaneous ignition for No. 1 and No. 2 plugs. It must be noted that some tachometers may register twice that of actual engine speed.
6. Check the idle speed when unloaded. (With headlights, heater fan, rear defroster, radiator fan, air conditioning, etc. OFF) Idle speed (No load and gears in neutral (MT vehicles), or N or P (AT vehicles) position): MT vehicles: 650+/-100 RPM AT vehicles: 700+/-100 RPM
7. Check the idle speed when loaded (Turn the air conditioning switch to "ON" and operate the compressor for at least 1 minute before measurement). Idle speed (A/C ON, no load and gears in neutral (MT vehicles) or N or P (AT vehicles) position): 850+/-100 RPM NOTE: Idle speed is automatically adjusted and can not be adjusted manually. If the specified idle speed can not be maintained, refer to General On-board Diagnosis Table under "Engine Control System". See «BASIC DIAGNOSTIC PROCEDURES»(/subaru/impreza-wrx/gdgg-2002-2005/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures)

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1. Warm-up the engine.
2. To check the ignition timing, connect a timing light to No. 1 cylinder spark plug cord, and illuminate the timing mark with timing light.
3. Start the engine and check the ignition timing at idle speed. Ignition timing (BTDC/RPM): MT vehicles 10°+/-8°/650 AT vehicles 15°+/-8°/700 If the timing is not correct, check the ignition control system. Refer to Engine Control System. See «BASIC DIAGNOSTIC PROCEDURES»(/subaru/impreza-wrx/gdgg-2002-2005/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures)

1. Warm up the engine.
2. Disconnect the brake vacuum hose from the manifold and install a vacuum gauge.
3. Keep the engine at idle speed, and then read the vacuum gauge indication.

By observing the gauge needle movement, the internal condition of engine can be diagnosed as described below.

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Vacuum pressure (at idling, A/C "OFF"): Less than -60.0 kPa (-450 mm Hg, -17.72 in-Hg)

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1. Disconnect the ground cable from battery.
2. Remove the generator from bracket. See «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/charging-system/#generators-regulators-except-outback-sport__removal) , Generator
3. Disconnect the connector from oil pressure switch.
4. Remove the oil pressure switch from engine cylinder block. See «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/lubrication-system/#engine-lubrication-sysyem) , Oil Pressure Switch.
5. Connect the oil pressure gauge hose to cylinder block.
6. Connect the battery ground cable to battery.
7. Start the engine, and then measure the oil pressure. Oil pressure: 88 kPa (0.9 kg/cm 2 , 13 psi) or more at 800 RPM 294 kPa (3.0 kg/cm 2 , 43 psi) or more at 5,000 RPM CAUTION: If the oil pressure is out of specification, check the oil pump, oil filter and lubrication line. See «INSPECTION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/lubrication-system/#engine-lubrication-sysyem) , Engine Lubrication System Troubles. If the oil pressure warning light is turned ON and oil pressure is in specification, replace the oil pressure switch. See «INSPECTION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/lubrication-system/#engine-lubrication-sysyem) , Engine Lubrication System Troubles. NOTE: The specified data is based on an engine oil temperature of 80°C (176°F).
8. After measuring the oil pressure, install the oil pressure switch. See «INSTALLATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/lubrication-system/#engine-lubrication-sysyem) , Oil Pressure Switch. Tightening torque: 25 N.m (2.5 kgf-m, 18.1 ft-lb)
9. Install the generator and V-belt in the reverse order of removal, and then adjust the V-belt deflection. «INSTALLATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , V-belt.

Note. If the fuel pressure is out of specification, check or replace the pressure regulator and pressure regulator vacuum hose.

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1. Lower the fuel pressure, see «FUEL SYSTEM PRESSURE RELEASE»(/subaru/impreza-wrx/gdgg-2002-2005/remont/removal-installation/#engine-controls-removal-installation-impreza-outback-sport__fuel-system-pressure-release) , Fuel.
2. Open the fuel flap lid, and then remove the fuel filler cap.
3. Disconnect the fuel delivery hoses from fuel filter, and then connect the fuel pressure gauge.
4. Connect the connector of fuel pump relay.
5. Start the engine.
6. Measure the fuel pressure while disconnecting the pressure regulator vacuum hose from intake manifold. Fuel pressure: Standard; 284-314 kPa (2.9-3.2 kg/cm 2 , 41-46 psi)
7. After connecting the pressure regulator vacuum hose, measure the fuel pressure. Fuel pressure: Standard; 206-235 kPa (2.1-2.4 kg/cm 2 , 30-34 psi) NOTE: The fuel pressure gauge registers 10 to 20 kPa (0.1 to 0.2 kg/cm 2 , 1 to 3 psi) higher than standard values during high-altitude operations.

Note. Inspection and adjustment of the valve clearance should be performed while engine is cold.

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1. Set the vehicle on a lift.
2. Lift up the vehicle.
3. Remove the under cover.
4. Lower the vehicle.
5. Disconnect the ground cable from battery.
6. Remove the timing belt cover (LH).
7. When inspecting No. 1 and No. 3 cylinders; Disconnect the spark plug cords from spark plugs on RH side. See «RH SIDE»(/subaru/impreza-wrx/gdgg-2002-2005/remont/ignition-system/#ignition-system-sohc__rh-side) , REMOVAL, Spark Plug. Disconnect the PCV hose from rocker cover (RH). Remove the bolts, and then remove the rocker cover (RH).
8. When inspecting No. 2 and No. 4 cylinders; Disconnect the spark plug cords from spark plugs on LH Side. See «LH SIDE»(/subaru/impreza-wrx/gdgg-2002-2005/remont/ignition-system/#ignition-system-sohc__lh-side) , REMOVAL, Spark Plug. Disconnect the PCV hose from rocker cover (LH). Remove the bolts, and then remove the rocker cover (LH).
9. Set the No. 1 cylinder piston to top dead center of compression stroke by rotating crankshaft pulley clockwise using ST. ST 499977100 CRANKSHAFT PULLEY WRENCH NOTE: When arrow mark (A) on the camshaft sprocket (LH) comes exactly to the top, No. 1 cylinder piston is at the top dead center of compression stroke.
10. Measure the No. 1 cylinder valve clearance by using a thickness gauge. CAUTION: Insert the thickness gauge (A) as parallel as possible with respect to the valve stem end face. Measure the exhaust valve clearances while lifting-up the vehicle. Valve clearance: Intake; 0.20+/-0.02 mm (0.0079+/-0.0008 in) Exhaust; 0.25+/-0.02 mm (0.0098+/-0.0008 in)
11. If necessary, adjust the valve clearance. See «ADJUSTMENT»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc__adjustment) Valve Clearance.
12. Similar to measurement procedures used for the No. 1 cylinder, measure the No. 2, 3 and 4 cylinder valve clearances. NOTE: Be sure to set the cylinder pistons to their respective top dead centers on compression stroke before measuring valve clearances. To set the No. 3, 2 and 4 cylinder pistons to their top dead centers on compression stroke, turn the crankshaft pulley clockwise 90° at a time starting with arrow mark on camshaft sprocket (LH) facing up.
13. After inspection, install the related parts in the reverse order of removal.

Tightening torque

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1. Resonator chamber; 33 N.m (3.4 kgf-m, 25 ft-lb)

ADJUSTMENT

Note. Adjustment of the valve clearance should be performed while engine is cold.

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1. Set the No. 1 cylinder piston to top dead center of compression stroke by rotating crankshaft pulley clockwise using ST. ST 499977100 CRANKSHAFT PULLEY WRENCH NOTE: When arrow mark (A) on the camshaft sprocket (LH) comes exactly to the top, No. 1 cylinder piston is at the top dead center of compression stroke.
2. Adjust the No. 1 cylinder valve clearance. Loosen the valve rocker nut and screw. Place a suitable thickness gauge. While noting the valve clearance, tighten the valve rocker adjust screw. When specified valve clearance is obtained, tighten the valve rocker nut. Tightening torque: 10 N.m (1.0 kgf-m, 7.2 ft-lb) CAUTION: Insert the thickness gauge as parallel as possible with respect to the valve stem end face. Adjust the exhaust valve clearances while lifting up the vehicle. Valve clearance: Intake; 0.20+/-0.02 mm (0.0079+/-0.0008 in) Exhaust; 0.25+/-0.02 mm (0.0098+/-0.0008 in)
3. Ensure the valve clearances are within specifications.
4. Turn the crankshaft two complete rotations until No. 1 cylinder piston is set again to the top dead center on compression stroke.
5. Ensure the valve clearances are within specifications. If necessary, readjust the valve clearances.
6. Similar to adjustment procedures used for the No. 1 cylinder, adjust the No. 2, 3 and 4 cylinder valve clearances. NOTE: Be sure to set the cylinder pistons to their respective top dead centers on compression stroke before adjusting valve clearances. To set the No. 3, 2 and 4 cylinder pistons to their top dead centers on compression stroke, turn the crankshaft pulley clockwise 90° at a time starting with arrow mark on camshaft sprocket (LH) facing up.

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1. Set the vehicle on a lift.
2. Open the front hood fully, and then support with the hood stay.
3. Lower the fuel pressure, see «FUEL SYSTEM PRESSURE RELEASE»(/subaru/impreza-wrx/gdgg-2002-2005/remont/removal-installation/#engine-controls-removal-installation-impreza-outback-sport__fuel-system-pressure-release) , Fuel.
4. Collect the refrigerant, and then remove the pressure hoses. See «OPERATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/manual-hvac-system/#hvac) , Refrigerant Recovery Procedure. Place and connect the attachment hose to refrigerant recycle system. Collect the refrigerant from A/C system. Disconnect the A/C pressure hoses from A/C compressor.
5. Remove the fuel filler cap.
6. Disconnect the ground cable from battery.
7. Remove the air intake duct and air cleaner case. See «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#air-intake-system-h4so) , Air Intake Duct and «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#air-intake-system-h4so) , Air Cleaner Case.
8. Remove the under cover.
9. Remove the radiator from vehicle. See «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/cooling-fan/#engine-cooling-system) , Radiator.
10. Remove the air cleaner case stay. MT model AT model
11. Disconnect the following connectors and cables. Front oxygen (A/F) sensor connector Rear oxygen sensor connector Engine ground cable Engine harness connectors Generator connector, terminal and A/C compressor connector Accelerator cable (A) and cruise cable (B) Pressure switch
12. Disconnect the following hoses. Brake booster vacuum hose Heater inlet and outlet hoses
13. Remove the power steering pump from bracket. Remove the resonator chamber. Loosen the lock bolt and slider bolt, and then remove the front side V-belt. See «FRONT SIDE BELT»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc__front-side-belt) , REMOVAL, V-belt. Remove the pipe with brackets. Remove the bolts which installs power steering pump bracket. Remove the power steering tank from bracket by pulling it upward. Place the power steering pump on right side wheel apron.
14. Remove the front and center exhaust pipe. See «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/exhaust/#exhaust-system-h4so__removal) , Front Exhaust Pipe.
15. Remove the nuts which hold lower side of transmission to engine.
16. Remove the nuts which install front cushion rubber onto front crossmember.
17. Separate the torque converter clutch from drive plate. (AT vehicles) Lower the vehicle. Remove the service hole plug. Remove the bolts which hold torque converter clutch to drive plate. Remove other bolts while rotating the engine using ST. ST 499977100 CRANKSHAFT PULLEY WRENCH
18. Remove the pitching stopper.
19. Disconnect fuel delivery hose (A), return hose (B) and evaporation hose (C). CAUTION: Disconnect the hose with its end wrapped with cloth to prevent fuel from splashing. Catch fuel from the hose into container.
20. Support the engine with a lifting device and wire ropes.
21. Support the transmission with a floor jack. CAUTION: Before moving the engine away from the transmission, check to be sure no work has been overlooked. Doing this is very important because the transmission lowers under its own weight. This is also very important in order to facilitate re-installation.
22. Separation of the engine and transmission. Remove the starter, see «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/starter/#starters-except-outback-sport__removal) , Starter. Remove the bolts which hold upper side of transmission to engine.
23. Install ST to torque converter clutch case (AT vehicles). ST 498277200 STOPPER SET
24. Remove the engine from vehicle. Slightly raise the engine. Raise the transmission with floor jack. Move the engine horizontally until main shaft is withdrawn from clutch cover. Slowly move the engine away from engine compartment. NOTE: Be careful not to damage the adjacent parts or body panels with crankshaft pulley, oil level gauge, etc.
25. Remove front cushion rubbers.

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1. Install the front cushion rubbers. Tightening torque: 34 N.m (3.5 kgf-m, 25.3 ft-lb)
2. Install the engine onto transmission. Position the engine in engine compartment and align it with transmission. NOTE: Be careful not to damage the adjacent parts or body panels with crankshaft pulley, oil level gauge, etc. Apply a small amount of grease to the splines of main shaft. (MT vehicles)
3. Tighten the bolts which hold upper side of transmission to engine. Tightening torque: 50 N.m (5.1 kgf-m, 36.9 ft-lb)
4. Remove the lifting device and wire ropes.
5. Remove the floor jack.
6. Install the pitching stopper. Tightening torque: T1: 50 N.m (5.1 kgf-m, 37 ft-lb) T2: 58 N.m (5.9 kgf-m, 43 ft-lb)
7. Remove the ST from torque converter clutch case. (AT vehicles) NOTE: Be careful not to drop the ST into torque converter clutch case when removing ST. ST 498277200 STOPPER SET
8. Install the starter, see «INSTALLATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/starter/#starters-except-outback-sport__installation) , Starter.
9. Install the torque converter clutch onto drive plate. (AT vehicles) Tighten the bolts which hold torque converter clutch to drive plate. Tighten other bolts while rotating the engine by using ST. NOTE: Be careful not to drop the bolts into torque converter clutch housing. ST 499977100 CRANKSHAFT PULLEY WRENCH Tightening torque: 25 N.m (2.5 kgf-m, 18.1 ft-lb) Plug the service hole to prevent entry of foreign substances.
10. Install the power steering pump on bracket. Install the power steering tank on bracket. Install the power steering pump on bracket, and then tighten the bolts. Tightening torque: 20.1 N.m (2.05 kgf-m, 14.8 ft-lb) Tighten the bolts which install power steering pump bracket, and then install the spark plug cords. Connect the power steering switch connector. Install the front side V-belt, and adjust it. See «FRONT SIDE BELT»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , INSTALLATION, V-belt. Install the resonator chamber. Tightening torque: 33 N.m (3.4 kgf-m, 24.6 ft-lb)
11. Tighten the nuts which hold lower side of transmission to engine. Tightening torque: 50 N.m (5.1 kgf-m, 36.9 ft-lb)
12. Tighten the nuts which install front cushion rubber onto crossmember. Tightening torque: 85 N.m (8.7 kgf-m, 63 ft-lb) NOTE: Make sure the front cushion rubber mounting bolts (A) and locator (B) are securely installed.
13. Install the front and center exhaust pipe. «INSTALLATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/exhaust/#exhaust-system-h4so__installation) , Front Exhaust Pipe.
14. Connect the following hoses. Fuel delivery hose, return hose and evaporation hose Heater inlet and outlet hoses Brake booster vacuum hose
15. Connect the following connectors. Engine ground cable Tightening torque: 14 N.m (1.4 kgf-m, 10.1 ft-lb) Engine harness connectors Generator connector and terminal A/C compressor connector Power steering pressure switch
16. Connect the following cables. Accelerator cable Cruise control cable (vehicles with cruise control)
17. Adjust each connected cable.
18. Install the air cleaner case stay. Tightening torque: 16 N.m (1.6 kgf-m, 11.6 ft-lb)
19. Install the A/C pressure hoses, see «INSTALLATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/manual-hvac-system/#hvac) , Hose and Tube. NOTE: Use new O-rings. Tightening torque: 25 N.m (2.5 kgf-m, 18.1 ft-lb)
20. Install the radiator to vehicle. See «INSTALLATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/cooling-fan/#engine-cooling-system) , Radiator.
21. Install the air intake duct and air cleaner case. See «INSTALLATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#air-intake-system-h4so) , Air Cleaner Case and «INSTALLATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#air-intake-system-h4so) , Air Intake Duct.
22. Install the under cover.
23. Install battery in the vehicle, and then connect the cables.
24. Fill engine coolant, see «FILLING OF ENGINE COOLANT»(/subaru/impreza-wrx/gdgg-2002-2005/remont/cooling-fan/#engine-cooling-system) , Replacement, Engine Coolant.
25. Check the ATF level and correct if necessary. (AT vehicles). See «INSPECTION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/automatic-trans/#overhaul__inspection) , ATF.
26. Charge the A/C system with refrigerant, see «OPERATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/manual-hvac-system/#hvac) , Refrigerant Charging Procedure.
27. Remove the front hood stay, and then close the front hood.
28. Take off the vehicle from lift arms.

1. Make sure the pipes and hoses are installed correctly.
2. Make sure the engine coolant and ATF are at specified levels.

REMOVAL

1. Remove the engine assembly, see «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc__removal) Engine Assembly.
2. Remove the engine mounting from engine assembly.

INSTALLATION

Install in the reverse order of removal.

Tightening torque

1. Engine mounting: 34 N.m (3.5 kgf-m, 25.3 ft-lb)

Make sure that no cracks or other damage exists.

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1. After removing the engine from body, secure it in the ST as shown below. ST1 498457000 ENGINE STAND ADAPTER RH ST2 498457100 ENGINE STAND ADAPTER LH ST3 499817100 ENGINE STAND
2. In this section the procedures described under each index are all connected and stated in order. It will be the complete procedure for overhauling of the engine itself when you go through all steps in the process. Therefore, in this section, to conduct the particular procedure within the flow of a section, you need to go back and conduct the procedure described previously in order to do that particular procedure.

FRONT SIDE BELT

Note. Perform the following procedures 1 to 4 with the engine installed to body.

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1. Remove the V-belt cover.
2. Loosen the lock bolt (A).
3. Loosen the slider bolt (B).
4. Remove the front side belt (C).

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1. Loosen the lock nut (A).
2. Loosen the slider bolt (B).
3. Remove the A/C belt.
4. Remove the A/C belt tensioner.

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1. Wipe off any oil or water on the belt and pulley.
2. Install the belt (C), and tighten the slider bolt (B) so as to obtain the specified belt tension. See «INSPECTION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , V-belt.
3. Tighten the lock bolt (A).
4. Tighten the slider bolt (B). Tightening torque: Lock bolt through bolt; 25 N.m (2.5 kgf-m, 18.1 ft-lb) Slider bolt; 8 N.m (0.8 kgf-m, 5.5 ft-lb)

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1. Install the belt, and tighten the slider bolt (B) so as to obtain the specified belt tension. See «INSPECTION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , V-belt.
2. Tighten the lock nut (A). Tightening torque: Lock nut (A); 22.6 N.m (2.3 kgf-m, 16.6 ft-lb)

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1. Replace the belts, if cracks, fraying or wear is found.
2. Check the drive belt tension and adjust it if necessary by changing the generator installing position and/or idler pulley installing position. Belt tension: (A) New: 7 - 9 mm (0.276 - 0.354 in) Reused: 9 - 11 mm (0.354 - 0.433 in) (B) New: 7.5 - 8.5 mm (0.295 - 0.335 in) Reused: 9.0 - 10.0 mm (0.354 - 0.394 in)

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1. Remove the V-belt, see «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , V-Belt.
2. Remove the crankshaft pulley bolt. To lock the crankshaft, use ST. ST 499977100 CRANKSHAFT PULLEY WRENCH
3. Remove the crankshaft pulley.

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1. Install the crankshaft pulley.
2. Install the pulley bolt. To lock the crankshaft, use ST. ST 499977100 CRANKSHAFT PULLEY WRENCH Clean the crankshaft pulley threads using an air gun. Apply engine oil to the crankshaft pulley bolt seat and threads. Tighten the bolts temporarily to a torque of 44 N.m (4.5 kgf-m, 33 ft-lb). Tighten the crankshaft pulley bolts. Tightening torque: 177 N.m (18.0 kgf-m, 130.2 ft-lb)
3. Confirm that the tightening angle of crankshaft pulley bolt is 65° or more. If the tightening angle of crankshaft pulley bolt is less than 65°, conduct the following procedures. Replace the crankshaft pulley bolts. Crankshaft pulley bolt: 12369AA011 Clean the crankshaft threads using an air gun. Apply engine oil to the crankshaft pulley bolt seat and threads. Tighten the bolts temporarily to a torque of 44 N.m (4.5 kgf-m, 33 ft-lb). Tighten the crankshaft pulley bolts for a further angle of 65° - 75°. NOTE: Conduct the tightening procedures by confirming the turning angle of crankshaft pulley bolt referring to the gauge indicated on timing belt cover.
4. Install the A/C belt tensioner.
5. Install the A/C belt.

1. Make sure the V-belt is not worn or otherwise damaged.
2. Check the tension of the belt. See «INSPECTION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , V-belt.

Scheme 324

1. Remove the V-belt, see «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , V-Belt.
2. Remove the crankshaft pulley, see «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Crankshaft Pulley.
3. Remove the timing belt cover (LH).
4. Remove the front timing belt cover.

Scheme 325

1. Install the front timing belt cover. Tightening torque: 5 N.m (0.5 kgf-m, 3.6 ft-lb)
2. Install the timing belt cover (LH). Tightening torque: 5 N.m (0.5 kgf-m, 3.6 ft-lb)
3. Install the crankshaft pulley, see «INSTALLATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Crankshaft Pulley.
4. Install the V-belt, see «INSTALLATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , V-belt.

Make sure the cover is not damaged.

Scheme 326

Scheme 327

Scheme 328

Scheme 329

Scheme 330

Scheme 331

Scheme 332

1. Remove the V-belt, see «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , V-Belt.
2. Remove the crankshaft pulley, see «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Crankshaft Pulley.
3. Remove the timing belt cover, see «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Timing Belt Cover.
4. Remove the timing belt guide. (MT vehicles)
5. If the alignment mark (a) and/or arrow mark (which indicates rotation direction) on timing belt are faded away, put new marks before removing the timing belt as shown in procedures below. Turn the crankshaft by using ST. Align the mark (a) of sprocket to cylinder block notch (b) and ensure the right side cam sprocket mark (c), cam cap and cylinder head matching surface (d) and/or left side cam sprocket mark (e) and belt cover notch (f) are properly adjusted. ST 499987500 CRANKSHAFT SOCKET Using white paint, put alignment and/or arrow marks on the timing belts in relation to crankshaft sprocket and camshaft sprockets. Specified data: Z 1 : 46.8 tooth length Z 2 : 43.7 tooth length
6. Remove belt idler (No. 2).
7. Remove the timing belt.

Scheme 333

Scheme 334

1. Remove belt idler (No. 1).
2. Remove the automatic belt tension adjuster assembly.

Scheme 335

Scheme 336

Scheme 337

1. Preparation for installation of automatic belt tension adjuster assembly: CAUTION: Always use a vertical type pressing tool to move the adjuster rod down. Do not use a lateral type vise. Push the adjuster rod vertically. Press-in the push adjuster rod gradually taking more than 3 minutes. Do not allow press pressure to exceed 9,807 N (1,000 kgf, 2,205 lb). Press the adjuster rod as far as the end surface of the cylinder. Do not press the adjuster rod into the cylinder. Doing so may damage the cylinder. Do not release the press pressure until stopper pin is completely inserted. Attach the automatic belt tension adjuster assembly to the vertical pressing tool. Slowly move the adjuster rod down with a pressure of 294 N (30 kgf, 66 lb) until the adjuster rod is aligned with the stopper pin hole in the cylinder. With a 2 mm (0.08 in) diameter stopper pin or a 2 mm (0.08 in) (nominal) diameter hex bar wrench inserted into the stopper pin hole in the cylinder, secure the adjuster rod.
2. Install the automatic belt tension adjuster assembly. Tightening torque: 39 N.m (4.0 kgf-m, 28.9 ft-lb)
3. Install belt idler (No. 1). Tightening torque: 39 N.m (4.0 kgf-m, 28.9 ft-lb)

Scheme 338

Scheme 339

Scheme 340

Scheme 341

Scheme 342

Scheme 343

Scheme 344

1. Preparation for installation of automatic belt tension adjuster assembly. See «AUTOMATIC BELT TENSION ADJUSTER ASSEMBLY AND BELT IDLER»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , INSTALLATION, Timing Belt.
2. Installation of timing belt Turn the camshaft sprocket No. 2 using ST1, and then turn the camshaft sprocket No. 1 using ST2 so that their alignment marks (A) come to top positions. ST1 18231AA010 CAMSHAFT SPROCKET WRENCH NOTE: Also the CAMSHAFT SPROCKET WRENCH (499207100) can be used. ST2 499207400 CAMSHAFT SPROCKET WRENCH While aligning alignment mark on the timing belt (B) with marks on sprockets (A), position the timing belt properly.
3. Install belt idler (No. 2). Tightening torque: 39 N.m (4.0 kgf-m, 28.9 ft-lb)
4. After ensuring that the marks on timing belt and camshaft sprockets are aligned, remove the stopper pin from belt tension adjuster.
5. Install the timing belt guide (MT vehicles). Temporarily tighten the remaining bolts. Check and adjust the clearance between timing belt and timing belt guide by using a thickness gauge. Clearance: 1.0+/-0.5 mm (0.039+/-0.020 in) Tighten the remaining bolts. Tightening torque: 10 N.m (1.0 kgf-m, 7.2 ft-lb )
6. Install the timing belt cover, see «INSTALLATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Timing Belt Cover.
7. Install the crankshaft pulley, see «INSTALLATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Crankshaft Pulley.
8. Install the V-belt, see «INSTALLATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , V-belt.

TIMING BELT

1. Check the timing belt teeth for breaks, cracks, and wear. If any fault is found, replace the belt.
2. Check the condition of back side of the belt. If any cracks are found, replace the belt.

1. Bending radius: h 60 mm (2.36 in) or more

Scheme 345

Scheme 346

1. Visually check oil seals for leaks, and rod ends for abnormal wear or scratches. If necessary, replace faulty parts.
2. Check that the adjuster rod does not move when a pressure of 294 N (30 kgf, 66 lb) is applied to it. This is to check adjuster rod's stiffness.
3. If the adjuster rod is not stiff enough and moves freely when applying 294 N (30 kgf, 66 lb), check it using the following procedures: Slowly press the adjuster rod down to the end surface of the cylinder. Repeat this motion 2 or 3 times. With the adjuster rod moved all the way up, apply a pressure of 294 N (30 kgf, 66 lb) to it. Check adjuster rod's stiffness. If the adjuster rod is not stiff enough and moves down, replace the automatic belt tension adjuster assembly with a new one. CAUTION: Always use a vertical type pressing tool to move the adjuster rod down. Do not use a lateral type vise. Push the adjuster rod vertically. Press-in the push adjuster rod gradually taking more than 3 minutes. Do not allow press pressure to exceed 9,807 N (1,000 kgf, 2, 205 lb). Press the adjuster rod as far as the end surface of the cylinder. Do not press the adjuster rod into the cylinder. Doing so may damage the cylinder.
4. Measure the extension of rod beyond the body. If it is not within specifications, replace with a new one. Rod extension: H 5.7+/-0.5 mm (0.224+/-0.020 in)

BELT TENSION PULLEY

1. Check the mating surfaces of timing belt and contact point of adjuster rod for abnormal wear or scratches. Replace the automatic belt tension adjuster assembly if faulty.
2. Check the tension pulley for smooth rotation. Replace if noise or excessive play is noted.
3. Check the tension pulley for grease leakage.

BELT IDLER

1. Check the belt idler for smooth rotation. Replace if noise or excessive play is noted.
2. Check the belt outer contacting surfaces of idler pulley for abnormal wear and scratches.
3. Check the belt idler for grease leakage.

Scheme 347

Scheme 348

1. Remove the V-belt, see «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , V-Belt.
2. Remove the crankshaft pulley, see «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Crankshaft Pulley.
3. Remove the timing belt cover, see «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Timing Belt Cover.
4. Remove the timing belt, see «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Timing Belt.
5. Remove the camshaft position sensor. See «REMOVAL & INSTALLATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/removal-installation/#engine-controls-removal-installation-impreza-outback-sport) , Camshaft Position Sensor.
6. Remove camshaft sprocket No. 2, to lock the camshaft, use ST. ST 18231AA010 CAMSHAFT SPROCKET WRENCH NOTE: Also the CAMSHAFT SPROCKET WRENCH (499207100) can be used.
7. Remove camshaft sprocket No. 1, to lock the camshaft, use ST. ST 499207400 CAMSHAFT SPROCKET WRENCH

Scheme 349

Scheme 350

1. Install camshaft sprocket No. 1, to lock the camshaft, use ST. ST 499207400 CAMSHAFT SPROCKET WRENCH Tightening torque: 78 N.m (8.0 kgf-m, 57.9 ft-lb) NOTE: Do not confuse the right and left side camshaft sprockets during installation. The camshaft sprocket No. 2 is identified by a projection used to monitor the camshaft position sensor.
2. Install camshaft sprocket No. 2, to lock the camshaft, use ST. ST 18231AA010 CAMSHAFT SPROCKET WRENCH NOTE: Also the CAMSHAFT SPROCKET WRENCH (499207100) can be used. Tightening torque: 78 N.m (8.0 kgf-m, 57.9 ft-lb)
3. Install the camshaft position sensor. See «REMOVAL & INSTALLATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/removal-installation/#engine-controls-removal-installation-impreza-outback-sport) , Camshaft Position Sensor.
4. Install the timing belt, see «TIMING BELT»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Timing Belt.
5. Install the timing belt cover, see «INSTALLATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Timing Belt Cover.
6. Install the crankshaft pulley, see «INSTALLATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Crankshaft Pulley.
7. Install the V-belt, see «INSTALLATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , V-belt.

1. Check the sprocket teeth for abnormal wear and scratches.
2. Make sure there is no free play between sprocket and key.
3. Check the camshaft sprocket notch for sensor for damage and contamination of foreign matter.

Scheme 351

1. Remove the V-belt, see «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , V-Belt.
2. Remove the crankshaft pulley, see «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Crankshaft Pulley.
3. Remove the timing belt cover, see «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Timing Belt Cover.
4. Remove the timing belt, see «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Timing Belt.
5. Remove the camshaft sprocket, see «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Camshaft Sprocket.
6. Remove the crankshaft sprocket.

Scheme 352

1. Install the crankshaft sprocket.
2. Install the camshaft sprocket, see «INSTALLATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Camshaft Sprocket.
3. Install the timing belt, see «TIMING BELT»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Timing Belt.
4. Install the timing belt cover, see «INSTALLATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Timing Belt Cover.
5. Install the crankshaft pulley, see «INSTALLATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Crankshaft Pulley.
6. Install the V-belt, see «INSTALLATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , V-belt.

1. Check the sprocket teeth for abnormal wear and scratches.
2. Make sure there is no free play between sprocket and key.
3. Check the crankshaft sprocket notch for sensor for damage and contamination of foreign matter.

Scheme 353

Scheme 354

1. Remove the V-belt, see «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , V-Belt.
2. Remove the crankshaft pulley, see «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Crankshaft Pulley.
3. Remove the timing belt cover, see «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Timing Belt Cover.
4. Remove the timing belt, see «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Timing Belt.
5. Remove the camshaft sprocket, see «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Camshaft Sprocket.
6. Disconnect the PCV hose and remove rocker cover.
7. Removal of valve rocker assembly Remove bolts (a) through (h) in alphabetical sequence. NOTE: Leave two or three threads of bolts (g and h) engaged to retain the valve rocker assembly. Remove the valve rocker assembly.

Scheme 355

1. Installation of valve rocker assembly Temporarily tighten bolts (a) through (d) equally as shown in the figure. NOTE: Do not allow the valve rocker assembly to gouge knock pins. Tighten bolts (e) through (h) to specified torque. Tighten bolts (a) through (d) to specified torque. Tightening torque: 25 N.m (2.5 kgf-m, 18.1 ft-lb)
2. Adjust the valve clearance, see «ADJUSTMENT»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc__adjustment) Valve Clearance.
3. Install the rocker cover and connect PCV hose.
4. Install the camshaft sprocket, see «INSTALLATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Camshaft Sprocket.
5. Install the timing belt, see «TIMING BELT»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Timing Belt.
6. Install the timing belt cover, see «INSTALLATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Timing Belt Cover.
7. Install the crankshaft pulley, see «INSTALLATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Crankshaft Pulley.
8. Install the V-belt, see «INSTALLATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , V-belt.

DISASSEMBLY

1. Remove the bolts which secure rocker shaft.
2. Extract the rocker shaft. Remove the valve rocker arms, springs and shaft supports from rocker shaft. NOTE: Arrange all removed parts in order so that they can be installed in their original positions.
3. Remove the nut and adjuster screw from valve rocker.

ASSEMBLY

1. Install the adjuster screw and nut to valve rocker.
2. Arrange the valve rocker arms, springs and shaft supports in assembly order and insert valve rocker shaft. Tightening torque (shaft supports installing bolts): 5 N.m (0.5 kgf-m, 3.6 ft-lb) NOTE: Valve rocker arms, rocker shaft and shaft supports have identification marks. Ensure the parts with same markings are properly assembled.
3. Install the valve rocker shaft securing bolts.

Scheme 356

Scheme 357

1. Measure the inside diameter of valve rocker arm and outside diameter of valve rocker shaft, and determine the difference between the two (= oil clearance). Clearance between arm and shaft: Standard; 0.020 - 0.054 mm (0.0008 - 0.0021 in) Limit; 0.10 mm (0.0039 in)
2. If oil clearance exceeds the limit, replace the valve rocker arm or shaft, whichever shows greater amount of wear. Rocker arm inside diameter: 22.020 - 22.041 mm (0.8669 - 0.8678 in) Rocker shaft diameter: 21.987 - 22.000 mm (0.8656 - 0.8661 in)
3. If cam or valve contact surface of valve rocker arm is excessively worn or dented, replace the valve rocker arm.
4. Check that the valve rocker arm roller rotates smoothly. If not, replace the valve rocker arm.

Scheme 358

Scheme 359

Scheme 360

Scheme 361

Scheme 362

Scheme 363

1. Remove the V-belt, see «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , V-Belt.
2. Remove the crankshaft pulley, see «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Crankshaft Pulley.
3. Remove the timing belt cover, see «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Timing Belt Cover.
4. Remove the timing belt, see «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Timing Belt.
5. Remove the camshaft sprocket, see «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Camshaft Sprocket.
6. Remove the crankshaft sprocket, see «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Crankshaft Sprocket.
7. Remove timing belt cover No. 2 (LH).
8. Remove timing belt cover No. 2 (RH). NOTE: Do not damage or lose the seal rubber when removing timing belt covers.
9. Remove the tensioner bracket.
10. Remove the camshaft position sensor support. (LH side only)
11. Remove the oil level gauge guide. (LH side only)
12. Remove the valve rocker assembly, see «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Valve Rocker Assembly.
13. Remove the camshaft cap. Remove bolts (a) through (b) in alphabetical sequence. Equally loosen bolts (c) through (j) all the way in alphabetical sequence. Remove bolts (k) through (p) in alphabetical sequence using ST. ST 499497000 TORX PLUS Remove the camshaft cap.
14. Remove the camshaft.
15. Remove the oil seal.
16. Remove the plug from rear side of camshaft. CAUTION: Do not remove the oil seal unless necessary. Do not scratch the journal surface when removing oil seal.

Scheme 364

Scheme 365

Scheme 366

Scheme 367

Scheme 368

Scheme 369

Scheme 370

Scheme 371

Scheme 372

Scheme 373

Scheme 374

1. Apply a thin coat of engine oil to the camshaft journals, and then install the camshaft.
2. Install the camshaft cap. Apply liquid gasket on the camshaft cap. Liquid gasket: Three Bond 1280B P/N K0877YA018 NOTE: Apply a 3 mm (0.12 in) diameter (A) bead of liquid gasket along edge (B) of the camshaft cap (C) mating surface. Temporarily tighten bolts (g) through (j) in alphabetical sequence. Install the valve rocker assembly. Tighten bolts (a) through (h) in alphabetical sequence. Tightening torque: 25 N.m (2.5 kgf-m, 18.1 ft-lb) Tighten the TORX bolts (i) through (n) in alphabetical sequence using ST. ST 499497000 TORX PLUS Tightening torque: 18 N.m (1.8 kgf-m, 13.0 ft-lb) Tighten bolts (o) through (v) in alphabetical sequence. Tightening torque: 10 N.m (1.0 kgf-m, 7.2 ft-lb) Tighten bolts (w) through (x) in alphabetical sequence. Tightening torque: 10 N.m (1.0 kgf-m, 7.2 ft-lb)
3. Apply a thin coat of grease to oil seal lips, and then install the oil seal (A) on camshaft using ST1 and ST2. NOTE: Use a new oil seal. ST1 499597000 OIL SEAL GUIDE ST2 499587500 OIL SEAL INSTALLER
4. Install the plug using ST. ST 499587700 CAMSHAFT OIL SEAL INSTALLER
5. Adjust the valve clearance, see «ADJUSTMENT»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc__adjustment) Valve Clearance.
6. Install the rocker cover and connect PCV hose.
7. Install the oil level gauge guide. (LH side only)
8. Install the camshaft position sensor support. (LH side only)
9. Install the tensioner bracket. Tightening torque: 25 N.m (2.5 kgf-m, 18.1 ft-lb)
10. Install timing belt cover No. 2 (RH). Tightening torque: 5 N.m (0.5 kgf-m, 3.6 ft-lb)
11. Install timing belt cover No. 2 (LH). Tightening torque: 5 N.m (0.5 kgf-m, 3.6 ft-lb)
12. Install the crankshaft sprocket, see «INSTALLATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Crankshaft Sprocket.
13. Install the camshaft sprocket, see «INSTALLATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Camshaft Sprocket.
14. Install the timing belt, see «TIMING BELT»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Timing Belt.
15. Install the timing belt cover, see «INSTALLATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Timing Belt Cover.
16. Install the crankshaft pulley, see «INSTALLATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Crankshaft Pulley.
17. Install the V-belt, see «INSTALLATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , V-belt.

Scheme 375

Scheme 376

Scheme 377

Scheme 378

1. Measure the bend, and repair or replace if necessary. Limit: 0.025 mm (0.0010 in)
2. Check the journal for damage and wear. Replace if defective.
3. Measure the outside diameter of camshaft journal and inside diameter of cylinder head journal, and determine the difference between the two (= oil clearance). If the oil clearance exceeds specifications, replace the camshaft or cylinder head as necessary.
4. Check the cam face condition and remove minor faults by grinding with oil stone. Measure cam height H. Replace if the value exceeds the specified limit. Cam base circle diameter A: Intake; 34.00 mm (1.3386 in) Exhaust; 34.00 mm (1.3386 in)

CAMSHAFT SUPPORT

Measure the thrust clearance of camshaft with a dial gauge. If the clearance exceeds the limit, replace the camshaft support.

1. Standard: 0.030 - 0.090 mm (0.0012 - 0.0035 in)
2. Limit: 0.10 mm (0.0039 in)

Scheme 379

Scheme 380

Scheme 381

1. Remove the V-belt, see «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , V-Belt.
2. Remove the crankshaft pulley, see «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Crankshaft Pulley.
3. Remove the timing belt cover, see «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Timing Belt Cover.
4. Remove the timing belt, see «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Timing Belt.
5. Remove the camshaft sprocket, see «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Camshaft Sprocket.
6. Remove the intake manifold. See «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#air-intake-system-h4so) , Intake Manifold.
7. Remove the bolt which installs A/C compressor bracket on cylinder head.
8. Remove the valve rocker assembly, see «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Valve Rocker Assembly.
9. Remove the camshaft, see «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Camshaft.
10. Remove the cylinder head bolts in alphabetical sequence shown in the figure. NOTE: Leave bolts (a) and (c) engaged by three or four threads to prevent cylinder head from falling.
11. While tapping the cylinder head with a plastic hammer, separate it from cylinder block.
12. Remove bolts (a) and (c) to remove cylinder head.
13. Remove the cylinder head gasket. CAUTION: Do not scratch the mating surface of cylinder head and cylinder block.
14. Similarly, remove the right side cylinder head.

Scheme 382

1. Install the cylinder head and gaskets on cylinder block. CAUTION: Use new cylinder head gaskets. Be careful not to scratch the mating surface of cylinder block and cylinder head.
2. Tighten the cylinder head bolts. Apply a coat of engine oil to the washers and bolt threads. Tighten all bolts to 29 N.m (3.0 kgf-m, 22 ft-lb) in alphabetical sequence. Then tighten all bolts to 69 N.m (7.0 kgf-m, 51 ft-lb) in alphabetical sequence. Back off all bolts in reverse order of assembly by 180° first; back them off by 180° again. Tighten the bolts (a) and (b) to 34 N.m (3.5 kgf-m, 25 ft-lb). Tighten bolts (c), (d), (e) and (f) to 15 N.m (1.5 kgf-m, 11 ft-lb). Tighten all bolts by 80 to 90° in alphabetical sequence. CAUTION: Do not tighten bolts more than 90°. Further tighten all bolts by 80 to 90° in alphabetical sequence shown in figure below. CAUTION: Ensure that the total "re-tightening angle" [in the former two steps], do not exceed 180°.
3. Install the camshaft, see «INSTALLATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Camshaft.
4. Install the valve rocker assembly, see «INSTALLATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Valve Rocker Assembly.
5. Install the A/C compressor bracket on cylinder head.
6. Install the intake manifold. See «INSTALLATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#air-intake-system-h4so) , Intake Manifold.
7. Install the camshaft sprocket, see «INSTALLATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Camshaft Sprocket.
8. Install the timing belt, see «TIMING BELT»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Timing Belt.
9. Install the timing belt cover, see «INSTALLATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Timing Belt Cover.
10. Install the crankshaft pulley, see «INSTALLATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Crankshaft Pulley.
11. Install the V-belt, see «INSTALLATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , V-belt.

Scheme 383

1. Place the cylinder head on ST. ST 498267800 CYLINDER HEAD TABLE
2. Set the ST on valve spring. Compress the valve spring, and then remove the valve spring retainer key. Remove each valve and valve spring. ST 499718000 VALVE SPRING REMOVER CAUTION: Mark each valve to prevent confusion. Use extreme care not to damage the lips of intake valve oil seals and exhaust valve oil seals.

Scheme 384

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Scheme 386

1. Installation of valve spring and valve Place the cylinder head on ST. ST 498267800 CYLINDER HEAD TABLE Coat the stem of each valve with engine oil and insert valve into valve guide. NOTE: When inserting the valve into valve guide, use special care not to damage the oil seal lip. Install the valve spring and retainer. NOTE: Be sure to install the valve springs with their close-coiled end facing the seat on the cylinder head. Set the ST on valve spring. ST 499718000 VALVE SPRING REMOVER Compress the valve spring, and then fit the valve spring retainer key. After installing, tap the valve spring retainers lightly with a plastic hammer for better seating.

Scheme 387

Scheme 388

1. Check the valve springs for damage, free length, and tension. Replace the valve spring if it is not to the specifications presented below.
2. To measure the squareness of valve spring, stand the spring on a surface plate and measure its deflection at the top using a try square.

INTAKE AND EXHAUST VALVE OIL SEAL

In the following cases, replace the oil seal with a new one using pliers to pinch and remove the seal from the valve.

1. The lip is damaged.
2. The spring is out of place.
3. Valve and valve seat need reconditioning.
4. Valve guide needs replacement.

Scheme 389

1. Place the cylinder head on ST1.
2. Press-fit oil seal to the specified dimension indicated in the figure using ST2. CAUTION: Apply engine oil to oil seal before press-fitting. When press-fitting oil seal, do not use a hammer or drive the seal. Differentiate between intake valve oil seal and exhaust valve oil seal by noting their difference in color. ST1 498267800 CYLINDER HEAD TABLE ST2 498857100 VALVE OIL SEAL GUIDE Color of rubber part: Intake [Black] Exhaust [Brown] Color of spring part: Intake [Silver] Exhaust [Silver]

Scheme 390

1. Make sure that no cracks or other damage exists. In addition to visual inspection, inspect important areas by means of red lead check. Also make sure that gasket installing surface shows no trace of fuel and water leaks.
2. Place the cylinder head on ST. ST 498267800 CYLINDER HEAD TABLE
3. Measure the warping of the cylinder head surface that mates with crankcase using a straight edge and thickness gauge. If the warping exceeds 0.05 mm (0.0020 in), regrind the surface with a surface grinder. Warping limit; 0.05 mm (0.0020 in) Grinding limit; 0.1 mm (0.004 in) Standard height of cylinder head; 97.5 mm (3.839 in) NOTE: Uneven torque for the cylinder head bolts can cause warping. When reassembling, pay special attention to the torque so as to tighten evenly.

VALVE SEAT

Inspect the intake and exhaust valve seats, and then correct the contact surfaces with valve seat cutter if they are defective or when valve guides are replaced.

Valve seat width: W

Scheme 391

Scheme 392

1. Intake (A): Standard; 1.1 mm (0.043 in) Limit; 1.8 mm (0.071 in)
2. Exhaust (B): Standard; 1.5 mm (0.059 in) Limit; 2.2 mm (0.087 in)

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Scheme 399

1. Check the clearance between valve guide and stem. The clearance can be checked by measuring the outside diameter of valve stem and the inside diameter of valve guide with outside and inside micrometers respectively. Clearance between the valve guide and valve stem: Standard: Intake; 0.035 - 0.062 mm (0.0014 - 0.0024 in) Exhaust; 0.040 - 0.067 mm (0.0016 - 0.0026 in) Limit: 0.15 mm (0.0059 in)
2. If the clearance between valve guide and stem exceeds the limit, replace the valve guide or valve itself whichever shows greater amount of wear. See the following procedure for valve guide replacement. Valve guide inner diameter: 6.000 - 6.012 mm (0.2362 - 0.2367 in) Valve stem outer diameters: Intake; 5.950 - 5.965 mm (0.2343 - 0.2348 in) Exhaust; 5.945 - 5.960 mm (0.2341 - 0.2346 in) Place the cylinder head on ST1 with the combustion chamber upward so that valve guides enter the holes in ST1. Insert the ST2 into valve guide and press it down to remove valve guide. ST1 498267800 CYLINDER HEAD TABLE ST2 499767200 VALVE GUIDE REMOVER Turn the cylinder head upside down and place ST as shown in the figure. Intake side: ST 499767700 VALVE GUIDE ADJUSTER Exhaust side: ST 499767800 VALVE GUIDE ADJUSTER Before installing new oversize valve guide, make sure that neither scratches nor damages exist on the inside surface of valve guide holes in cylinder head. Put new valve guide, coated with sufficient oil, in the cylinder, and then insert the ST1 into valve guide. Press in until the valve guide upper end is flush with the upper surface of ST2. ST1 499767200 VALVE GUIDE REMOVER Intake side: ST2 499767700 VALVE GUIDE ADJUSTER Exhaust side: ST2 499767800 VALVE GUIDE ADJUSTER Check the valve guide protrusion. Valve guide protrusion: L Intake; 20.0 - 20.5 mm (0.787 - 0.807 in) Exhaust; 16.5 - 17.0 mm (0.650 - 0.669 in) Ream the inside of valve guide with ST. Gently rotate the reamer clockwise while pressing it lightly into the valve guide. Return the reamer by also rotating it clockwise. After reaming, clean the valve guide to remove chips. CAUTION: Apply engine oil to the reamer when reaming. If the inner surface of the valve guide is scored, the edge of the reamer should be slightly ground with an oil stone. If the inner surface of the valve guide becomes shiny and the reamer does not produce chips, use a new reamer or repair the reamer. ST 499767400 VALVE GUIDE REAMER Recheck the contact condition between valve and valve seat after replacing valve guide.

Scheme 400

1. Inspect the flange and stem of valve, and replace if damaged, worn, or deformed, or if dimension "H" is less than the specified limit. H: Intake: Standard; 1.0 mm (0.039 in) Limit; 0.6 mm (0.024 in) Exhaust: Standard; 1.2 mm (0.047 in) Limit; 0.6 mm (0.024 in) Valve overall length: Intake; 120.6 mm (4.75 in) Exhaust; 121.7 mm (4.79 in)
2. Put a small amount of grinding compound on the seat surface and lap the valve and seat surface. See «VALVE SEAT»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc__valve-seat) , ADJUSTMENT, Cylinder Head. Install a new intake valve oil seal after lapping.

Note. Before conducting this procedure, drain the engine oil completely if applicable.

Scheme 401

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Scheme 414

1. Remove the intake manifold. See «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#air-intake-system-h4so) , Intake Manifold.
2. Remove the V-belt, see «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , V-Belt.
3. Remove the crankshaft pulley, see «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Crankshaft Pulley.
4. Remove the timing belt cover, see «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Timing Belt Cover.
5. Remove the timing belt, see «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Timing Belt.
6. Remove the camshaft sprocket, see «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Camshaft Sprocket.
7. Remove the crankshaft sprocket, see «REMOVAL»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , Crankshaft Pulley.
8. Remove the generator and A/C compressor with their brackets.
9. Remove the rocker cover.
10. Remove the cylinder head bolts in alphabetical sequence shown in the figure. NOTE: Leave bolts (a) and (c) engaged by three or four threads to prevent cylinder head from falling.
11. While tapping the cylinder head with a plastic hammer, separate it from cylinder block.
12. Remove bolts (a) and (c) to remove cylinder head.
13. Remove the cylinder head gasket. NOTE: Do not scratch the mating surface of cylinder head and cylinder block.
14. Similarly, remove the right side cylinder head.
15. Remove the clutch housing cover. (MT vehicles)
16. Remove the flywheel (MT vehicles) or drive plate (AT vehicles). Using the ST, lock the crankshaft. ST 498497100 CRANKSHAFT STOPPER MT model AT model
17. Remove the oil separator cover.
18. Remove the water by-pass pipe for heater.
19. Loosen the bolts in alphabetical sequence as shown in the figure, and then remove water pump.
20. Remove the oil pump from cylinder block. Use a flat-bladed screwdriver as shown in the figure when removing oil pump. NOTE: Be careful not to scratch the mating surface of cylinder block and oil pump.
21. Removal of oil pan Turn the cylinder block to face the No. 2 and No. 4 piston sides upward. Remove the bolts which secure oil pan to cylinder block. Insert a oil pan cutter blade between cylinder block-to-oil pan clearance, and then remove the oil pan. NOTE: Do not use a screwdriver or similar tool in place of oil pan cutter.
22. Remove the oil strainer stay.
23. Remove the oil strainer.
24. Remove the baffle plate.
25. Remove the oil filter with ST. ST 498547000 OIL FILTER WRENCH
26. Remove the water pipe.
27. Remove the service hole cover and service hole plugs using hexagon wrench [14 mm (0.55 in)].
28. Rotate the crankshaft to bring No. 1 and No. 2 pistons to bottom dead center position, and then remove the piston snap ring through service hole of No. 1 and No. 2 cylinders. ST 499897200 PISTON SNAP RING PLIERS
29. Draw out the piston pin from No. 1 and No. 2 pistons using ST. ST 499097700 PISTON PIN REMOVER NOTE: Be careful not to confuse the original combination of piston, piston pin and cylinder.
30. Similarly remove the piston pins from No. 3 and No. 4 pistons.
31. Remove the bolts which connect cylinder block on the side of No. 2 and No. 4 cylinders.
32. Back off the bolts which connect cylinder block on the side of No. 1 and No. 3 cylinders two or three turns.
33. Set up the cylinder block so that No. 1 and No. 3 cylinders are on the upper side, and then remove the cylinder block connecting bolts.
34. Separate the cylinder blocks (RH) and (LH). NOTE: When separating the cylinder block, do not allow the connecting rod to fall and damage the cylinder block.
35. Remove the rear oil seal.
36. Remove the crankshaft together with connecting rod.
37. Remove the crankshaft bearings from cylinder block using a hammer's handle. NOTE: Do not confuse the combination of crankshaft bearings. Press bearing at the end opposite to locking lip.
38. Draw out each piston from cylinder block using a wooden bar or a hammer's handle. NOTE: Do not confuse the combination of piston and cylinder.

Note. Remove oil from the mating surface of bearing and cylinder block before installation. Also apply a thin coat of engine oil to crankshaft pins.

Scheme 415

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Scheme 445

Scheme 446

1. Position the crankshaft on No. 2 and No. 4 cylinder block.
2. Apply liquid gasket to the mating surface of No. 1 and No. 3 cylinder block, and position it on No. 2 and No. 4 cylinder block. Liquid gasket: Part No. 004403007 Three Bond 1215 or equivalent NOTE: Do not allow liquid gasket to get into O-ring grooves, oil passages, bearing grooves, etc.
3. Tighten the 10 mm cylinder block connecting bolts in alphabetical sequence shown in the figure. (LH side) Tightening torque: 15 N.m (1.5 kgf-m, 11.1 ft-lb)
4. Tighten the 10 mm cylinder block connecting bolts in alphabetical sequence shown in the figure. (RH side) Tightening torque: 15 N.m (1.5 kgf-m, 11.1 ft-lb)
5. Further tighten LH side bolts (A) - (D) by 90° in alphabetical sequence.
6. Further tighten RH side bolts (E) - (J) by 90° in alphabetical sequence.
7. Tighten the 8 mm and 6 mm cylinder block connecting bolts in alphabetical sequence shown in the figure. Tightening torque: (A) - (G): 25 N.m (2.5 kgf-m, 18.1 ft-lb) (H): 6.4 N.m (0.65 kgf-m, 4.7 ft-lb)
8. Install the rear oil seal using ST1 and ST2. ST1 499597100 OIL SEAL GUIDE ST2 499587200 OIL SEAL INSTALLER
9. Position the top ring gap at (A) or (B) in the figure.
10. Position the second ring gap at 180° on the reverse side for top ring gap.
11. Position the expander gap at (C) in the figure.
12. Position the lower rail gap at (D) in the figure. NOTE: Align the lower rail stopper (F) to the lateral hole (E) on the piston.
13. Position the upper rail gap within (G) in the figure. CAUTION: Ensure ring gaps do not face the same direction. Ensure ring gaps are not within the piston skirt area.
14. Install snap ring. Install snap rings in the piston holes located opposite service holes in cylinder block, when positioning all pistons in the corresponding cylinders. NOTE: Use new snap rings. CAUTION: Piston front mark faces towards the front of the engine.
15. Installing piston Turn the cylinder block to face the No. 1 and No. 2 piston side upward. Using the ST1, turn the crankshaft so that No. 1 and No. 2 connecting rods are set at bottom dead center. ST1 499987500 CRANKSHAFT SOCKET Apply a thin coat of engine oil to pistons and cylinders, and then insert the pistons in their cylinders using ST2. ST2 498747300 PISTON GUIDE
16. Installing piston pin Apply a thin coat of engine oil to the ST3 before insertion. Insert the ST3 into service hole to align piston pin hole with connecting rod small end. ST1 499017100 PISTON GUIDE Apply a thin coat of engine oil to the piston pin, and then insert the piston pin into piston and connecting rod through service hole. Install snap ring. NOTE: Use new snap rings. ST 499897200 PISTON SNAP RING PLIERS Apply liquid gasket around the service hole plug. Liquid gasket: Part No. 004403007 Three Bond 1215 or equivalent Install the service hole plug and gasket. NOTE: Use a new gasket. Turn the cylinder block to face the No. 3 and No. 4 piston side upward. Using the same procedures as used for No. 1 and No. 2 cylinders, install the pistons and piston pins.
17. Install the water pipe.
18. Install the baffle plate. Tightening torque: 6.4 N.m (0.65 kgf-m, 4.7 ft-lb)
19. Install the oil strainer and O-ring. Tightening torque: 10 N.m (1.0 kgf-m, 7 ft-lb)
20. Install the oil strainer stay.
21. Apply liquid gasket to the matching surfaces, and then install the oil pan. Liquid gasket: Part No. 004403007 Three Bond 1215 or equivalent
22. Apply liquid gasket to the matching surfaces, and then install the oil separator cover. Liquid gasket: Part No. 004403007 Three Bond 1215 or equivalent
23. Install the flywheel or drive plate. To lock the crankshaft, use ST. ST 498497100 CRANKSHAFT STOPPER Tightening torque: 72 N.m (7.3 kgf-m, 52.8 ft-lb) MT model AT model
24. Install the housing cover.
25. Installation of oil pump Discard the front oil seal after removal. Replace with a new one using the ST. ST 499587100 OIL SEAL INSTALLER Apply liquid gasket to the matching surface of oil pump. Liquid gasket: Part No. 004403007 Three Bond 1215 or equivalent Apply a thin coat of engine oil to the inside of oil seal. Install the oil pump on cylinder block. Be careful not to damage the oil seal during installation. Tightening torque: 6.4 N.m (0.6 kgf-m, 4.7 ft-lb) CAUTION: Do not forget to install the O-ring and seal when installing oil pump. Align flat surface of oil pump's inner rotor with crankshaft before installation.
26. Install the water pump and gasket. Tightening torque: First; 12 (1.2 kgf-m, 8.7 ft-lb) Second; 12 (1.2 kgf-m, 8.7 ft-lb) CAUTION: Be sure to use a new gasket. When installing the water pump, tighten the bolts in two stages in alphabetical sequence as shown in the figure.
27. Install the water by-pass pipe for heater.
28. Install the oil filter using ST. ST 498547000 OIL FILTER WRENCH
29. Tighten the cylinder head bolts. (Scheme 447) Apply a thin coat of engine oil to the washers and bolt threads. Tighten all bolts to 29 N.m (3.0 kgf-m, 22 ft-lb) in alphabetical sequence. Then tighten all bolts to 69 N.m (7.0 kgf-m, 51 ft-lb) in alphabetical sequence. Back off all bolts by 180° first; back them off by 180° again. Tighten the bolts (a) and (b) to 34 N.m (3.5 kgf-m, 25 ft-lb). Tighten bolts (c), (d), (e) and (f) to 15 N.m (1.5 kgf-m, 11 ft-lb). Tighten all bolts by 80 to 90° in alphabetical sequence. CAUTION: Do not tighten bolts more than 90°. Further tighten all bolts by 80 to 90° in alphabetical sequence. CAUTION: Ensure that the total "re-tightening angle" [in the former two steps], do not exceed 180°.
30. Install the oil level gauge guide, and then tighten the attaching bolt (left side only).
31. Install the rocker cover.
32. Install the crankshaft sprocket, see «INSTALLATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc), Crankshaft Sprocket.
33. Install the camshaft sprocket, see «INSTALLATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc), Camshaft Sprocket.
34. Install the timing belt, see «TIMING BELT»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc), Timing Belt.
35. Install the timing belt cover, see «INSTALLATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc), Timing Belt Cover.
36. Install the crankshaft pulley, see «INSTALLATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc), Crankshaft Pulley.
37. Install the generator and A/C compressor brackets on cylinder head.
38. Install the V-belt, see «INSTALLATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc), V-belt.
39. Install the intake manifold. See «INSTALLATION»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#air-intake-system-h4so), Intake Manifold.

Scheme 447

1. Remove the connecting rod cap.
2. Remove the connecting rod bearing. NOTE: Arrange the removed connecting rod, connecting rod cap and bearing in order to prevent confusion.
3. Remove the piston rings using a piston ring expander.
4. Remove the oil ring by hand. NOTE: Arrange the removed piston rings in good order to prevent confusion.
5. Remove the snap ring.

Scheme 448

1. Apply oil to the surfaces of the connecting rod bearings.
2. Install the connecting rod bearings on connecting rods and connecting rod caps.
3. Position each connecting rod with the marked side facing forward, and then install them.
4. Install the connecting rod cap with connecting rod nut. Ensure the arrow on connecting rod cap faces the front during installation. CAUTION: Each connecting rod has its own mating cap. Make sure that they are assembled correctly by checking their matching number. When tightening the connecting rod nuts, apply oil on the threads.
5. Install the expander, lower rail and upper rail in this order by hand. Then install the second ring and top ring with a piston ring expander.

CYLINDER BLOCK

1. Visually check for cracks and damage. Especially, inspect the important parts by means of red lead check.
2. Check the oil passages for clogging.
3. Inspect the crankcase surface that mates with cylinder head for warping by using a straight edge, and correct by grinding if necessary. Warping limit; 0.05 mm (0.0020 in) Grinding limit; 0.1 mm (0.004 in) Standard height of cylinder block; 201.0 mm (7.91 in)

Scheme 449

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Scheme 451

1. The cylinder bore size is stamped on cylinder block's front upper surface. NOTE: Measurement should be performed at a temperature 20°C (68°F). Standard sized pistons are classified into two grades, "A" and "B". These grades should be used as a guideline in selecting a standard piston. Standard diameter: A: 99.505 - 99.515 mm (3.9175 - 3.9179 in) B: 99.495 - 99.505 mm (3.9171 - 3.9175 in)
2. How to measure the inner diameter of each cylinder. Measure the inner diameter of each cylinder in both the thrust and piston pin directions at the heights shown in the figure, using a cylinder bore gauge. NOTE: Measurement should be performed at a temperature 20°C (68°F). Taper: Standard; 0.015 mm (0.0006 in) Limit; 0.050 mm (0.0020 in) Out-of-roundness: Standard; 0.010 mm (0.0004 in) Limit; 0.050 mm (0.0020 in)
3. When the piston is to be replaced due to general or cylinder wear, determine a suitable sized piston by measuring the piston clearance.
4. How to measure the outer diameter of each piston. Measure the outer diameter of each piston at the height shown in the figure. (Thrust direction) NOTE: Measurement should be performed at a temperature 20°C (68°F). Piston grade point H: 37.0 mm (1.457 in) Standard: A: 99.485 - 99.495 mm (3.9167 - 3.9171 in) B: 99.475 - 99.485 mm (3.9163 - 3.9167 in) 0.25 mm (0.0098 in) Oversize: 99.725 - 99.735 mm (3.9262 - 3.9266 in) 0.50 mm (0.0197 in) Oversize: 99.975 - 99.985 mm (3.9360 - 3.9364 in)
5. Calculate the clearance between cylinder and piston. NOTE: Measurement should be performed at a temperature 20°C (68°F). Cylinder to piston clearance at 20°C (68°F): Standard; 0.010 - 0.030 mm (0.0004 - 0.0012 in) Limit; 0.050 mm (0.0020 in)

BORING AND HONING

1. If the value of taper, out-of-roundness, or cylinder-to-piston clearance measured exceeds the specified limit or if there is any damage on the cylinder wall, rebore it to use an oversize piston. CAUTION: When any of the cylinders needs reboring, all other cylinders must be bored at the same time, and use oversized pistons. Do not perform boring on one cylinder only. Also, do not use an oversize piston for one cylinder only.
2. If the cylinder inner diameter exceeds the limit after boring and honing, replace the crankcase. NOTE: Immediately after reboring, the cylinder diameter may differ from its real diameter due to temperature rise. Thus, pay attention to this when measuring the cylinder diameter.

1. Limit of cylinder enlarging (Boring): 0.5 mm (0.020 in)

Scheme 452

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Scheme 454

1. Check the pistons and piston pins for damage cracks, and wear and the piston ring grooves for wear and damage. Replace if defective.
2. Measure the piston-to-cylinder clearance each cylinder. See «CYLINDER AND PISTON»(/subaru/impreza-wrx/gdgg-2002-2005/remont/mechanical/#engine-mecahnical-25l-sohc) , INSPECTION, Cylinder Block.
3. Make the sure that piston pin can be inserted into piston pin hole with a thumb at 20°C (68° Replace if defective). Standard clearance between piston pin and hole in piston: Standard; 0.004 - 0.008 mm (0.0002 - 0.0003 in) Limit; 0.020 mm (0.0008 in)
4. Check the snap ring installation groove on piston for burrs (A). If necessary, remove the burr from groove so that piston pin can lightly move.
5. Check the piston pin snap ring for distortion, cracks and wear.

Scheme 455

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Scheme 459

1. If the piston ring is broken, damaged, or worn, or if its tension is insufficient, or when the piston is replaced, replace the piston ring with a new one of the same size as the piston. CAUTION: Marks are shown on the end of top and second rings. When installing the rings to piston, face these marks upward. Oil ring is composed of upper rail, expander and lower rail. Be careful of the rail direction when installing oil ring to the piston.
2. Clean the piston ring groove and piston ring.
3. Squarely place the piston ring and oil ring in cylinder, and then measure the piston ring gap with a thickness gauge.
4. Measure the clearance between piston ring and piston ring groove with a thickness gauge.

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1. Replace the connecting rod, if the large or small end thrust surface is damaged.
2. Check for bend or twist using a connecting rod aligner. Replace the connecting rod if the bend or twist exceeds the limit. Limit of bend or twist per 100 mm (3.94 in) in length: 0.10 mm (0.0039 in)
3. Install the connecting rod fitted with bearing to crankshaft, and then measure the side clearance (thrust clearance). Replace the connecting rod if the side clearance exceeds the specified limit. Connecting rod side clearance: Standard; 0.070 - 0.330 mm (0.0028 - 0.0130 in) Limit; 0.4 mm (0.016 in)
4. Inspect the connecting rod bearing for scar, peeling, seizure, melting, wear, etc.
5. Measure the oil clearance on individual connecting rod bearings by means of plastigage. If any oil clearance is not within specification, replace the defective bearing with a new one of standard size or undersize as necessary. (See the table below.) Connecting rod oil clearance: Standard; 0.012 - 0.038 mm (0.0005 - 0.0015 in) Limit; 0.05 mm (0.0020 in)
6. Inspect the bushing at connecting rod small end, and replace if worn or damaged. Also measure the piston pin clearance at connecting rod small end. Clearance between piston pin and bushing: Standard; 0 - 0.022 mm (0 - 0.0009 in) Limit; 0.030 mm (0.0012 in)
7. Replacement procedure is as follows. Remove the bushing from connecting rod with ST and press. Press the bushing with ST after applying oil on the periphery of bushing. ST 499037100 CONNECTING ROD BUSHING REMOVER AND INSTALLER Make two 3 mm (0.12 in) holes in bushing. Ream the inside of bushing. After the completion of reaming, clean the bushing to remove chips.

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Scheme 469

Scheme 470

1. Clean the crankshaft completely and check for cracks by means of red lead check etc., and replace if defective. Replace if defective.
2. Measure the crankshaft bend. Repair or place if the value exceeds the specified limit. NOTE: If a suitable V-block is not available, install the No. 1 and No. 5 crankshaft bearing on cylinder block, position the crankshaft on these bearings and measure the crankshaft bend using a dial gauge. Crankshaft bend limit: 0.035 mm (0.0014 in)
3. Inspect the crank journal and crank pin for wear. If they are not within the specifications, replace the bearing with a suitable (undersize) one, and then replace or recondition the crankshaft as necessary. When grinding the crank journal or crank pin, finish them to specified dimensions according to the undersize bearing to be used. Crank pin and crank journal: Out-of-roundness; Less than 0.020 mm (0.0008 in) Taper limit; 0.07 mm (0.0028 in) Grinding limit; 0.250 mm (0.0098 in)
4. Measure the thrust clearance of crankshaft at center bearing. If the clearance exceeds the limit, replace bearing. Crankshaft thrust clearance: Standard 0.030 - 0.115 mm (0.0012 - 0.0045 in) Limit 0.25 mm (0.0098 in)
5. Inspect the individual crankshaft bearings for signs of flaking, seizure, melting, and wear.
6. Measure the oil clearance on each crankshaft bearing by means of plastigage. If the measurement is not within the specified range, replace the defective bearing with an undersize one, and then replace or recondition the crankshaft as necessary.

Note. "RANK" shown in the chart refer to the possibility of reason for the trouble in order ("Very often" to "Rarely")

A - Very often

B - Sometimes

C - Rarely

Scheme 471

Scheme 472

Scheme 473

Scheme 474

Scheme 475

Note. When disconnecting fuel injector connector, CHECK ENGINE malfunction indicator light illuminates and a diagnostic trouble code is stored in the ECM memory. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . Therefore, carry out the CLEAR MEMORY MODE after connecting the fuel injector connector. See CLEARING DIAGNOSTIC TROUBLE CODES .

Scheme 476

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

Scheme 477

Scheme 478

Scheme 479

Scheme 480

Scheme 481

Scheme 482

Scheme 483

See also:
• FUEL SYSTEM PRESSURE RELEASE
• REMOVAL
• BASIC DIAGNOSTIC PROCEDURES
• REMOVAL
• REMOVAL
• RH SIDE
• LH SIDE
• OPERATION
• REMOVAL
• REMOVAL
• REMOVAL
• REMOVAL
• INSTALLATION
• INSTALLATION
• INSPECTION
• REMOVAL & INSTALLATION
• DIAGNOSTIC TROUBLE CODE DEFINITIONS
• CLEARING DIAGNOSTIC TROUBLE CODES
• SPECIAL TOOLS
• ADJUSTMENT
• FRONT SIDE BELT
• REMOVAL
• VALVE SEAT