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Subaru 2004 Impreza Service Manual

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2004 IMPREZA SERVICE MANUAL

ENGINE SECTION 1

This service manual has been prepared
to provide SUBARU service personnel
with the necessary information and data
for the correct maintenance and repair
of SUBARU vehicles.
This manual includes the procedures
for maintenance, disassembling, reas-
sembling, inspection and adjustment of
components and diagnostics for guid-
ance of experienced mechanics.
Please peruse and utilize this manual
fully to ensure complete repair work for
satisfying our customers by keeping
their vehicle in optimum condition.
When replacement of parts during
repair work is needed, be sure to use
SUBARU genuine parts.
All information, illustration and specifi-
cations contained in this manual are
based on the latest product information
available at the time of publication
approval.
FUJI HEAVY INDUSTRIES LTD.
QUICK REFERENCE INDEX
FUEL INJECTION (FUEL SYSTEMS)
EMISSION CONTROL
(AUX. EMISSION CONTROL DEVICES)
INTAKE (INDUCTION)
MECHANICAL
EXHAUST
COOLING
LUBRICATION
SPEED CONTROL SYSTEMS
IGNITION
STARTING/CHARGING SYSTEMS
ENGINE (DIAGNOSTICS)
FUEL INJECTION (FUEL SYSTEMS)
EMISSION CONTROL
(AUX. EMISSION CONTROL DEVICES)
INTAKE (INDUCTION)
MECHANICAL
EXHAUST
COOLING
FU(H4SO)
EC(H4SO)
IN(H4SO)
ME(H4SO)
EX(H4SO)
CO(H4SO)
LU(H4SO)
SP(H4SO)
IG(H4SO)
SC(H4SO)
EN(H4SO)(diag)
FU(H4SOw/oOBD)
EC(H4SOw/oOBD)
IN(H4SOw/oOBD)
ME(H4SOw/oOBD)
EX(H4SOw/oOBD)
CO(H4SOw/oOBD)
G1870GE2

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  • Page 1: Engine Section

    2004 IMPREZA SERVICE MANUAL QUICK REFERENCE INDEX ENGINE SECTION 1 FUEL INJECTION (FUEL SYSTEMS) FU(H4SO) EMISSION CONTROL EC(H4SO) (AUX. EMISSION CONTROL DEVICES) INTAKE (INDUCTION) IN(H4SO) MECHANICAL ME(H4SO) This service manual has been prepared to provide SUBARU service personnel EXHAUST EX(H4SO)
  • Page 2 2004 IMPREZA SERVICE MANUAL QUICK REFERENCE INDEX ENGINE SECTION 1 LUBRICATION LU(H4SOw/oOBD) SPEED CONTROL SYSTEMS SP(H4SOw/oOBD) IGNITION IG(H4SOw/oOBD) STARTING/CHARGING SYSTEMS SC(H4SOw/oOBD) EN(H4SOw/oOBD) ENGINE (DIAGNOSTICS) (diag) G1870GE2...

  • Page 3: Table Of Contents

    MECHANICAL ME(H4SO) Page General Description ..................2 Compression .....................26 Idle Speed ....................27 Ignition Timing...................28 Intake Manifold Vacuum................29 Engine Oil Pressure ..................30 Fuel Pressure....................31 Valve Clearance..................32 Engine Assembly ..................34 Engine Mounting ..................41 Preparation for Overhaul................42 V-belt......................43 Crankshaft Pulley ..................45 Timing Belt Cover..................47 Timing Belt Assembly................48 Camshaft Sprocket..................53 Crankshaft Sprocket..................55...

  • Page 4: General Description

    General Description MECHANICAL 1. General Description A: SPECIFICATIONS Model 1.6 L 2.0 L 2.5 L Horizontally opposed, liquid cooled, 4-cylinder, 4-stroke gasoline Type engine Valve arrangement Belt driven, single over-head camshaft, 4-valve/cylinder 87.9 × 65.8 99.5 × 79.0 Bore × Stroke 92 ×...
  • Page 5 General Description MECHANICAL Bend limit 0.025 mm (0.0010 in) 0.030 — 0.090 mm (0.0012 — 0.0035 in) Thrust clearance Limit 0.10 mm (0.0039 in) 39.378 — 39.478 mm (1.5503 — 1.5542 in) Intake Limit 39.278 mm (1.5464 in) 1.6 L 39.565 —...
  • Page 6 General Description MECHANICAL Surface warpage limit (mating with cylinder head) 0.05 mm (0.0020 in) Surface grinding limit 0.1 mm (0.004 in) Standard height 201.0 mm (7.91 in) 87.905 — 87.915 mm (3.4608 — 3.4612 in) 1.6 L 87.895 — 87.905 mm (3.4604 — 3.4608 in) 92.005 —...
  • Page 7 General Description MECHANICAL Bend twist per 100 mm (3.94 Limit 0.10 mm (0.0039 in) in) in length Connecting 0.070 — 0.330 mm (0.0028 — 0.0130 in) Side clearance Limit 0.4 mm (0.016 in) 0.010 — 0.038 mm (0.0004 — 0.0015 in) 1.6 L 2.0 L Limit...
  • Page 8 General Description MECHANICAL Bend limit 0.035 mm (0.0014 in) Out-of-roundness 0.020 mm (0.0008 in) or less Crank pin and crank journal Grinding limit 0.250 mm (0.0098 in) 47.984 — 48.000 mm (1.8891 — 1.8898 in) 0.03 mm (0.0012 in) 47.954 — 47.970 mm (1.8879 — 1.8886 in) 1.6 L 0.05 mm (0.0020 in) 47.934 —...
  • Page 9 General Description MECHANICAL 1.998 — 2.011 mm (0.0787 — 0.0792 in) 0.03 mm (0.0012 in) 2.017 — 2.020 mm (0.0794 — 0.0795 in) #1, #3 0.05 mm (0.0020 in) 2.027 — 2.030 mm (0.0798 — 0.0799 in) 0.25 mm (0.0098 in) 2.127 —...
  • Page 10 General Description MECHANICAL B: COMPONENT 1. TIMING BELT (12) (10) (13) (11) (15) (14) (16) ME-00376 Timing belt cover No. 2 (RH) (10) Belt idler No. 2 Tightening torque: N·m (kgf-m, ft-lb) Timing belt guide (MT model) (11) Camshaft sprocket No. 2 T1: 5 (0.5, 3.6) Crankshaft sprocket (12)
  • Page 11 General Description MECHANICAL 2. CYLINDER HEAD AND CAMSHAFT (10) (19) (14) (15) (16) (13) (10) (18) (17) (11) (19) (12) ME-00186 Rocker cover (RH) (11) Cylinder head (LH) Tightening torque: N·m (kgf-m, ft-lb) Intake valve rocker ASSY (12) Camshaft (LH) T1: <Ref.
  • Page 12 General Description MECHANICAL 3. VALVE ROCKER ASSEMBLY ME-00187 Intake valve rocker arm Rocker shaft support Tightening torque: N·m (kgf-m, ft-lb) Valve rocker nut Intake rocker shaft T1: 5 (0.5, 3.6) Valve rocker adjust screw Exhaust rocker shaft T2: 10 (1.0, 7.2) Spring Exhaust valve rocker arm T3: 25 (2.5, 18.1)
  • Page 13 General Description MECHANICAL 4. CYLINDER HEAD AND VALVE ASSEMBLY ME-00760 Exhaust valve Valve spring seat Retainer Intake valve Intake valve oil seal Retainer key Valve guide Valve spring Exhaust valve oil seal ME(H4SO)-11...
  • Page 14 General Description MECHANICAL 5. CYLINDER BLOCK (11) (10) (14) (10) (10) (10) (26) (15) (12) (17) (16) (22) (18) (24) (21) (23) (25) (13) (20) (19) FU-01016 Oil pressure switch (14) Baffle plate Tightening torque: N·m (kgf-m, ft-lb) Cylinder block (RH) (15) Oil filter connector T1: 5 (0.5, 3.6)
  • Page 15 General Description MECHANICAL 6. CRANKSHAFT AND PISTON (10) (11) (12) (14) (12) (13) (12) (11) (15) (18) (10) (9) (8) (17) (16) (17) (16) ME-00190 ME(H4SO)-13...
  • Page 16 General Description MECHANICAL Flywheel (MT model) Circlip (17) Crankshaft bearing #2, #4 Reinforcement (AT model) (10) Connecting rod bolt (18) Crankshaft bearing #5 Drive plate (AT model) (11) Connecting rod Top ring (12) Connecting rod bearing Tightening torque: N·m (kgf-m, ft-lb) Second ring (13) Connecting rod cap...

  • Page 17: Engine Mounting

    General Description MECHANICAL 7. ENGINE MOUNTING ME-00413 Front cushion rubber Front engine mounting bracket Tightening torque: N·m (kgf-m, ft-lb) T1: 35 (3.6, 25.8) T2: 42 (4.3, 31.0) T3: 85 (8.7, 63) ME(H4SO)-15...
  • Page 18 General Description MECHANICAL C: CAUTION • Be careful not to let oil, grease or coolant contact the timing belt, clutch disc and flywheel. • Wear working clothing, including a cap, protec- • All removed parts, if to be reused, should be re- tive goggles and protective shoes during operation.
  • Page 19 General Description MECHANICAL ILLUSTRATION TOOL NUMBER DESCRIPTION REMARKS 22771AA030 SUBARU Troubleshooting for electrical systems. SELECT MONI- • English: 22771AA030 (Without printer) TOR KIT • German: 22771AA070 (Without printer) • French: 22771AA080 (Without printer) • Spanish: 22771AA090 (Without printer) ST22771AA030 498267800 CYLINDER •...
  • Page 20 General Description MECHANICAL ILLUSTRATION TOOL NUMBER DESCRIPTION REMARKS 498457100 ENGINE STAND Used with ENGINE STAND (499817000). ADAPTER LH ST-498457100 498497100 CRANKSHAFT Used for stopping rotation of flywheel when loos- STOPPER ening and tightening crankshaft pulley bolt, etc. ST-498497100 498547000 OIL FILTER •...
  • Page 21 General Description MECHANICAL ILLUSTRATION TOOL NUMBER DESCRIPTION REMARKS 498747000 PISTON GUIDE Used for installing piston in cylinder. (1.6 L model) ST-498747000 398744300 PISTON GUIDE Used for installing piston in cylinder. (2.0 L model) ST-398744300 498747300 PISTON GUIDE Used for installing piston in cylinder. (2.5 L model) ST-498747300 498857100...
  • Page 22 General Description MECHANICAL ILLUSTRATION TOOL NUMBER DESCRIPTION REMARKS 499017100 PISTON PIN Used for installing piston pin, piston and connect- GUIDE ing rod. ST-499017100 499037100 CONNECTING Used for removing and installing connecting rod ROD BUSHING bushing. REMOVER & INSTALLER ST-499037100  499057000 Used for removing flywheel (Dual mass flywheel).
  • Page 23 General Description MECHANICAL ILLUSTRATION TOOL NUMBER DESCRIPTION REMARKS 499587500 OIL SEAL • Used for installing camshaft oil seal. INSTALLER • Used with OIL SEAL GUIDE (499597000). ST-499587500 499587700 CAMSHAFT OIL Used for installing cylinder head plug. SEAL INSTALLER ST-499587700 499097700 PISTON PIN Used for removing piston pin.
  • Page 24 General Description MECHANICAL ILLUSTRATION TOOL NUMBER DESCRIPTION REMARKS  499497000 Used for removing and installing camshaft cap. TORX PLUS ST-499497000 499587100 OIL SEAL Used for installing oil pump oil seal. INSTALLER ST-499587100 499597000 OIL SEAL GUIDE • Used for installing camshaft oil seal. •...
  • Page 25 General Description MECHANICAL ILLUSTRATION TOOL NUMBER DESCRIPTION REMARKS 499718000 VALVE SPRING Used for removing and installing valve spring. REMOVER ST-499718000 499767200 VALVE GUIDE Used for removing valve guides. REMOVER ST-499767200 499767400 VALVE GUIDE Used for reaming valve guides. REAMER ST-499767400 499767700 VALVE GUIDE Used for installing valve guide.
  • Page 26 General Description MECHANICAL ILLUSTRATION TOOL NUMBER DESCRIPTION REMARKS 499767800 VALVE GUIDE Used for installing valve guide. (Exhaust side) ADJUSTER ST-499767700 499817100 ENGINE STAND • Stand used for engine disassembly and assem- bly. • Used with ENGINE STAND ADAPTER RH (498457000) & LH (498457100). ST-499817100 499977400 CRANKSHAFT...

  • Page 27: Idle Speed

    General Description MECHANICAL ILLUSTRATION TOOL NUMBER DESCRIPTION REMARKS 499987500 CRANKSHAFT Used for rotating crankshaft. SOCKET ST-499987500 499897200 PISTON CIR- Used for removing and installing piston pin circlip. CLIP PLIERS ST-499897200 2. GENERAL PURPOSE TOOLS TOOL NAME REMARKS Compression Gauge Used for measuring compression. Tachometer (Secondary pick-up type) Used for measuring idle speed.

  • Page 28: Compression

    Compression MECHANICAL 2. Compression A: INSPECTION CAUTION: After warming up, engine becomes very hot. Be careful not to burn yourself during measure- ment. 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.

  • Page 29: Idle Speed

    2) Warm up the engine. 3) Stop the engine, and then turn the ignition switch to OFF. ME-00193 4) When using the Subaru Select Monitor, refer to NOTE: the following. <Ref. to ME(H4SO)-16, SPECIAL • When using the OBD-II general scan tool, care- TOOLS, PREPARATION TOOL, General Descrip- fully read its operation manual.

  • Page 30: Ignition Timing

    Ignition Timing MECHANICAL 4. Ignition Timing A: INSPECTION CAUTION: After warming up, engine becomes very hot. Be careful not to burn yourself during measure- ment. 1) Warm up the engine. 2) To check the ignition timing, connect a timing light to #1 cylinder spark plug cord, and illuminate the timing mark with timing light.

  • Page 31: Intake Manifold Vacuum

    Intake Manifold Vacuum MECHANICAL 5. Intake Manifold Vacuum A: INSPECTION 1) Warm up the engine. 2) Disconnect the brake vacuum hose, and then install the vacuum gauge to hose fitting on manifold. 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.

  • Page 32: Engine Oil Pressure

    Engine Oil Pressure MECHANICAL 6. Engine Oil Pressure CAUTION: • If the oil pressure is out of specification, A: INSPECTION check the oil pump, oil filter and lubrication 1) Disconnect the ground cable from battery. line. <Ref. to LU(H4SO)-21, INSPECTION, En- gine Lubrication System Trouble in General.>...

  • Page 33: Fuel Pressure

    Fuel Pressure MECHANICAL 7. Fuel Pressure NOTE: The fuel pressure gauge registers 10 to 20 kPa (0.1 A: INSPECTION to 0.2 kg/cm , 1 to 3 psi) higher than standard val- ues during high-altitude operations. WARNING: Before removing the fuel pressure gauge, lower the fuel pressure.

  • Page 34: Valve Clearance

    Valve Clearance MECHANICAL 8. Valve Clearance NOTE: When arrow mark (A) on the camshaft sprocket A: INSPECTION (LH) comes exactly to the top, #1 cylinder piston is brought to the top dead center of compression NOTE: stroke. Inspection and adjustment of the valve clearance should be performed while engine is cold.
  • Page 35 Valve Clearance MECHANICAL • To set each cylinder piston to its top dead center Valve clearance: on compression stroke in the following sequence: Intake; 0.20 ± ± ± ± 0.02 mm (0.0079 ± ± ± ± 0.0008 in) #3, #2 and #4 cylinder, turn the crankshaft pulley clockwise by every 180°...

  • Page 36: Engine Assembly

    Engine Assembly MECHANICAL 9. Engine Assembly • AT MODEL A: REMOVAL 1) Set the vehicle on a lift. 2) Open the front hood fully, and then support with the hood stay. 3) Using the refrigerant recovery system, dis- charge refrigerant. <Ref. to AC-21, OPERATION, Refrigerant Recovery Procedure.>...
  • Page 37 Engine Assembly MECHANICAL (4) Engine harness connectors 13) Disconnect the following hoses. (1) Brake booster vacuum hose FU-00826 FU-00879 (5) Generator connector, terminal and A/C compressor connector (2) Heater inlet outlet hose ( B ) ( A ) ME-00208 ME-00330 14) Remove the power steering pump from brack- (A) Generator connector and terminal (B) A/C compressor connector...
  • Page 38 Engine Assembly MECHANICAL (4) Remove the bolts which install the power 17) Remove the nuts which install the front cushion steering pump bracket. rubber onto front crossmember. FU-00139 ME-00211 18) Separate the torque converter clutch from drive (5) Remove the power steering tank from bracket by pulling it upward.
  • Page 39 Engine Assembly MECHANICAL • Catch fuel from the hose into container. (2) Remove the bolts which hold the upper side of transmission to engine. ( A) (B ) FU-00149 ME-00216 21) Support the engine with a lifting device and 24) Install the ST to torque converter clutch case. wire ropes.
  • Page 40 Engine Assembly MECHANICAL 2) Install the engine onto transmission. Tightening torque: (1) Position the engine in engine compartment T1: 50 N·m (5.1 kgf-m, 37 ft-lb) and align it with transmission. T2: 58 N·m (5.9 kgf-m, 43 ft-lb) NOTE: Be careful not to damage the adjacent parts or body panels with crank pulley, oil level gauge, etc.
  • Page 41 Engine Assembly MECHANICAL 10) Install the power steering pump on bracket. (5) Install the front side V-belt, and adjust it. <Ref. to ME(H4SO)-43, FRONT SIDE BELT, IN- (1) Install the power steering tank on bracket. STALLATION, V-belt.> (6) Install the resonator chamber. Tightening torque: 33 N·m (3.4 kgf-m, 24.6 ft-lb) FU-00020...
  • Page 42 Engine Assembly MECHANICAL 14) Connect the following hoses. (1) Fuel delivery hose, return hose and evapo- ration hose (2) Heater inlet and outlet hoses (3) Brake booster vacuum hose 15) Connect the following connectors. (1) Engine ground cables Tightening torque: 14 N·m (1.4 kgf-m, 10.1 ft-lb) (2) Engine harness connectors (3) Generator connector and terminal...

  • Page 43: Engine Mounting

    Engine Mounting MECHANICAL 10.Engine Mounting A: REMOVAL 1) Remove engine assembly. <Ref. ME(H4SO)-34, REMOVAL, Engine Assembly.> 2) Remove the engine mounting from engine as- sembly. B: INSTALLATION Install in the reverse order of removal. Tightening torque: Engine mounting; 35 N·m (3.6 kgf-m, 25.8 ft-lb) C: INSPECTION Make sure there are no cracks or other damage.

  • Page 44: Preparation For Overhaul

    Preparation for Overhaul MECHANICAL 11.Preparation for Overhaul A: PROCEDURE 1) After removing the engine from body, secure it in the ST shown below. ST1 498457000 ENGINE STAND ADAPTER ST2 498457100 ENGINE STAND ADAPTER ST3 499817100 ENGINE STAND ME-00221 2) In this section the procedures described under each index are all connected and stated in order.

  • Page 45: V-Belt

    V-belt MECHANICAL 12.V-belt 4) Remove the belt tensioner. A: REMOVAL 1. FRONT SIDE BELT NOTE: Perform the following procedures 1) to 4) with the engine installed to body. 1) Remove the V-belt cover. ME-00225 B: INSTALLATION NOTE: Wipe off any oil or water on the belt and pulley. 1.
  • Page 46 V-belt MECHANICAL 3) Tighten the lock nut (A). Belt tension (without belt tension gauge) Tightening torque: Lock nut (A): When installing new parts: 22.6 N·m (2.3 kgf-m, 16.6 ft-lb) 7 — 9 mm (0.276 — 0.354 in) At inspection: 9 — 11 mm (0.354 — 0.433 in) When installing new parts: 7.5 —...

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