Subaru Impreza 2004 Service Manual
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Subaru Impreza 2004 Service Manual

Engine section 2
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2004 IMPREZA SERVICE MANUAL

ENGINE SECTION 2

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)
FU(H4DOTC)
EC(H4DOTC)
IN(H4DOTC)
ME(H4DOTC)
EX(H4DOTC)
CO(H4DOTC)
LU(H4DOTC)
SP(H4DOTC)
IG(H4DOTC)
SC(H4DOTC)
EN(H4DOTC)(diag)
G1870GE3

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Summary of Contents for Subaru Impreza 2004

  • Page 1: Engine Section

    EC(H4DOTC) (AUX. EMISSION CONTROL DEVICES) INTAKE (INDUCTION) IN(H4DOTC) MECHANICAL ME(H4DOTC) This service manual has been prepared to provide SUBARU service personnel EXHAUST EX(H4DOTC) with the necessary information and data for the correct maintenance and repair of SUBARU vehicles. COOLING CO(H4DOTC)

  • Page 2: Table Of Contents

    MECHANICAL ME(H4DOTC) Page General Description ..................2 Compression .....................34 Idle Speed ....................35 Ignition Timing...................36 Intake Manifold Vacuum................37 Engine Oil Pressure ..................38 Fuel Pressure....................39 Valve Clearance..................40 Engine Assembly ..................44 Engine Mounting ..................52 Preparation for Overhaul................53 V-belt......................54 Crankshaft Pulley ..................56 Timing Belt Cover..................57 Timing Belt Assembly................58 Camshaft Sprocket..................66 Crankshaft Sprocket..................68...

  • Page 3: General Description

    General Description MECHANICAL 1. General Description A: SPECIFICATIONS 1. DOHC TURBO MODEL (EXCEPT FOR STi AND AUSTRALIA MODEL) Horizontally opposed, liquid cooled, 4-cylinder, Type 4-stroke gasoline engine Valve arrangement Belt driven, double overhead camshaft, 4-valve/cylinder Bore Stroke mm (in) 75 (3.62 2.95) Piston displacement 1,994 (121.67)
  • Page 4 General Description MECHANICAL Refacing angle 1.0 mm (0.039 in) Intake Valve seat Limit 1.7 mm (0.067 in) Contacting width 1.5 mm (0.059 in) Exhaust Limit 2.2 mm (0.087 in) Inner diameter 6.000 — 6.012 mm (0.2362 — 0.2367 in) Valve guide Protrusion above head 15.8 —...
  • Page 5 General Description MECHANICAL 0.20 — 0.25 mm (0.0079 — 0.0098 in) Top ring Limit 1.0 mm (0.039 in) 0.40 — 0.50 mm (0.016 — 0.020 in) Second Piston ring gap ring Limit 1.0 mm (0.039 in) 0.20 — 0.50 mm (0.0079 — 0.020 in) Piston ring Oil ring Limit...
  • Page 6 General Description MECHANICAL Bend limit 0.035 mm (0.0014 in) Out-of-roundness 0.005 mm (0.0002 in) or less Crank pin and crank jour- Grinding limit 0.25 mm (0.0098 in) 51.984 — 52.000 mm (2.0466 — 2.0472 in) 0.03 mm (0.0012 51.954 — 51.970 mm (2.0454 — 2.0461 in) in) US 0.05 mm Crank pin outer diameter...
  • Page 7 General Description MECHANICAL 1.998 — 2.011 mm (0.0787 — 0.0792 in) 0.03 mm (0.0012 2.017 — 2.020 mm (0.0794 — 0.0795 in) in) US 0.05 mm #1, #3 (0.0020 2.027 — 2.030 mm (0.0798 — 0.0799 in) in) US 0.25 mm (0.0098 2.127 —...
  • Page 8 General Description MECHANICAL Belt tension Protrusion of adjuster rod 5.2 — 6.2 mm (0.205 — 0.244 in) adjuster Spacer O.D. 17.955 — 17.975 mm (0.7069 — 0.7077 in) Tensioner bush I.D. 18.0 — 18.08 mm (0.7087 — 0.7118 in) 0.025 — 0.125 mm (0.0010 — 0.0049 in) Belt Clearance between spacer and bush tensioner...
  • Page 9 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) 92.005 — 92.015 mm (3.6222 — 3.6226 in) Cylinder bore 91.995 — 92.005 mm (3.6218 — 3.6222 in) 0.015 mm (0.0006 in) Taper Cylinder Limit...
  • Page 10 General Description MECHANICAL Bend limit 0.035 mm (0.0014 in) Out-of-roundness 0.005 mm (0.0002 in) or less Crank pin and crank jour- Grinding limit 0.25 mm (0.0098 in) 51.984 — 52.000 mm (2.0466 — 2.0472 in) 0.03 mm (0.0012 51.954 — 51.970 mm (2.0454 — 2.0461 in) in) US 0.05 mm Crank pin outer diameter...
  • Page 11 General Description MECHANICAL 1.998 — 2.011 mm (0.0787 — 0.0792 in) 0.03 mm (0.0012 2.017 — 2.020 mm (0.0794 — 0.0795 in) in) US 0.05 mm #1, #3 (0.0020 2.027 — 2.030 mm (0.0798 — 0.0799 in) in) US 0.25 mm (0.0098 2.127 —...
  • Page 12 General Description MECHANICAL Belt tension Protrusion of adjuster rod 5.2 — 6.2 mm (0.205 — 0.244 in) adjuster Spacer O.D. 17.955 — 17.975 mm (0.7069 — 0.7077 in) Tensioner bush I.D. 18.0 — 18.08 mm (0.7087 — 0.7118 in) 0.025 — 0.125 mm (0.0010 — 0.0049 in) Belt Clearance between spacer and bush tensioner...
  • Page 13 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) 92.005 — 92.015 mm (3.6222 — 3.6226 in) Cylinder bore 91.995 — 92.005 mm (3.6218 — 3.6222 in) 0.015 mm (0.0006 in) Taper Cylinder Limit...
  • Page 14 General Description MECHANICAL Bend limit 0.035 mm (0.0014 in) Out-of-roundness 0.005 mm (0.0002 in) or less Crank pin and crank jour- Grinding limit 0.25 mm (0.0098 in) 51.984 — 52.000 mm (2.0466 — 2.0472 in) 0.03 mm (0.0012 51.954 — 51.970 mm (2.0454 — 2.0461 in) in) US 0.05 mm Crank pin outer diameter...
  • Page 15 General Description MECHANICAL 1.998 — 2.011 mm (0.0787 — 0.0792 in) 0.03 mm (0.0012 2.017 — 2.020 mm (0.0794 — 0.0795 in) in) US 0.05 mm #1, #3 (0.0020 2.027 — 2.030 mm (0.0798 — 0.0799 in) in) US 0.25 mm (0.0098 2.127 —...
  • Page 16 General Description MECHANICAL B: COMPONENT 1. TIMING BELT • EXCEPT FOR STi AND AUSTRALIA MODEL (12) (14) (10) (14) (11) (17) (13) (15) (16) (18) ME-00601 Timing belt cover No. 2 (RH) (10) Intake camshaft sprocket (LH) Tightening torque: N·m (kgf-m, ft-lb) Timing belt guide (MT model) (11) Exhaust camshaft sprocket (LH)
  • Page 17 General Description MECHANICAL • STi AND AUSTRALIA MODEL (12) (14) (10) (14) (11) (17) (13) (15) (16) (18) ME-00704 Timing belt cover No. 2 (RH) (10) Intake camshaft sprocket (LH) Tightening torque: N·m (kgf-m, ft-lb) Timing belt guide (11) Exhaust camshaft sprocket (LH) T1: 5 (0.5, 3.6) Crankshaft sprocket (12)
  • Page 18 General Description MECHANICAL 2. CYLINDER HEAD AND CAMSHAFT • EXCEPT FOR STi AND AUSTRALIA MODEL (11) (13) (10) (15) (16) (12) (14) (16) (32) (17) (28) (29) (30) (13) (22) (21) (14) (31) (25) (24) (32) (18) (20) (19) (23) (26) (27) ME-00756...
  • Page 19 General Description MECHANICAL Rocker cover (RH) (15) Cylinder head (RH) (29) Gasket Rocker cover gasket (RH) (16) Cylinder head gasket (30) Oil filler duct Oil separator cover (17) Cylinder head (LH) (31) O-ring Gasket (18) Intake camshaft (LH) (32) Stud bolt Intake camshaft cap (Front RH) (19) Exhaust camshaft (LH)
  • Page 20 General Description MECHANICAL • STi AND AUSTRALIA MODEL (10) (12) (13) (11) (13) (28) (14) (24) (25) (26) (10) (18) (17) (11) (27) (22) (21) (28) (20) (15) (16) (19) (23) ME-00705 ME(H4DOTC)-19...
  • Page 21 General Description MECHANICAL Rocker cover (RH) (13) Cylinder head gasket (25) Gasket Rocker cover gasket (RH) (14) Cylinder head (LH) (26) Oil filler duct Oil flow control solenoid valve (15) Intake camshaft (LH) (27) O-ring assembly (RH) (16) Exhaust camshaft (LH) (28) Stud bolt Intake camshaft cap (RH)
  • Page 22 General Description MECHANICAL 3. CYLINDER HEAD AND VALVE ASSEMBLY (11) (11) (12) (10) (12) (10) ME-00003 Exhaust valve Intake valve oil seal Valve lifter Intake valve Valve spring (10) Exhaust valve oil seal Cylinder head Retainer (11) Intake valve guide Valve spring seat Retainer key (12)
  • Page 23 General Description MECHANICAL 4. CYLINDER BLOCK (10) (10) (14) (11) (10) (10) (27) (12) (10) (15) (19) (16) (18) (25) (20) (17) (13) (26) (23) (24) (22) (21) ME-00725 Oil pressure switch (16) Water by-pass pipe Tightening torque: N·m (kgf-m, ft-lb) Cylinder block (RH) (17) Connector...
  • Page 24 General Description MECHANICAL 5. CRANKSHAFT AND PISTON (10) (11) (12) (13) (10) (15) (14) (13) (14) (13) (10) (13) (16) (12) (11) (19) (17) (18) (18) (17) (10) ME-00005 Flywheel (MT model) (10) Circlip (19) Crankshaft bearing #5 Ball bearing (MT model) (11) Connecting rod bolt Reinforcement (AT model)

  • Page 25: Engine Mounting

    General Description MECHANICAL 6. ENGINE MOUNTING ME-00706 Heat shield cover Front engine mounting bracket Tightening torque: N·m (kgf-m, ft-lb) Front cushion rubber T1: 35 (3.6, 25.8) T2: 42 (4.3, 30.9) T3: 85 (8.7, 62.7) ME(H4DOTC)-24...
  • Page 26 General Description MECHANICAL C: CAUTION • Wear working clothing, including a cap, protec- tive goggles, and protective shoes during opera- tion. • Remove contamination including dirt and corro- sion before removal, installation or disassembly. • Keep the disassembled parts in order and pro- tect them from dust or dirt.

  • Page 27: Special Tools

    General Description MECHANICAL D: PREPARATION TOOL 1. SPECIAL TOOLS ILLUSTRATION TOOL NUMBER DESCRIPTION REMARKS 498267600 CYLINDER • Used for replacing valve guides. HEAD TABLE • Used for removing and installing valve springs. ST-498267600 498457000 ENGINE STAND Used with ENGINE STAND (499817000). ADAPTER RH ST-498457000 498457100...
  • Page 28 General Description MECHANICAL ILLUSTRATION TOOL NUMBER DESCRIPTION REMARKS 398744300 PISTON GUIDE Used for installing piston in cylinder for 2.0 L engine. ST-398744300 498857100 VALVE OIL SEAL Used for press-fitting of intake and exhaust valve GUIDE guide oil seals. ST-498857100 499017100 PISTON PIN Used for installing piston pin, piston and connect- GUIDE...
  • Page 29 General Description MECHANICAL ILLUSTRATION TOOL NUMBER DESCRIPTION REMARKS 499097600 PISTON PIN Used for removing piston pin. (Except for Australia REMOVER model) ASSY ST-499097600 499097700 PISTON PIN Used for removing piston pin. (Australia model REMOVER except for STi model) ASSY ST-499097700 499207400 CAMSHAFT Used for removing and installing exhaust cam-...
  • Page 30 General Description MECHANICAL ILLUSTRATION TOOL NUMBER DESCRIPTION REMARKS 499977500 CAMSHAFT Used for removing and installing intake camshaft SPROCKET sprocket. (STi and Australia model) WRENCH ST-499977500 499587200 CRANKSHAFT • Used for installing crankshaft oil seal. OIL SEAL • Used with CRANKSHAFT OIL SEAL GUIDE INSTALLER (499597100).
  • Page 31 General Description MECHANICAL ILLUSTRATION TOOL NUMBER DESCRIPTION REMARKS 18251AA020 VALVE GUIDE Used for installing intake and exhaust valve ADJUSTER guides. ST18251AA020 499767200 VALVE GUIDE Used for removing valve guides. REMOVER ST-499767200 499767400 VALVE GUIDE Used for reaming valve guides. REAMER ST-499767400 499817000 ENGINE STAND...
  • Page 32 General Description MECHANICAL ILLUSTRATION TOOL NUMBER DESCRIPTION REMARKS 499977400 CRANKSHAFT Used for stopping rotation of crankshaft pulley PULLEY when loosening and tightening crankshaft pulley WRENCH bolts. ST-499977400 499987500 CRANKSHAFT Used for rotating crankshaft. SOCKET ST-499987500 498547000 OIL FILTER • Used for removing and installing oil filter. WRENCH •...
  • Page 33 General Description MECHANICAL ILLUSTRATION TOOL NUMBER DESCRIPTION REMARKS 499587100 OIL SEAL Used for installing oil pump oil seal. INSTALLER ST-499587100 499587600 OIL SEAL Used for installing camshaft oil seal for DOHC INSTALLER engine. ST-499587600 499597200 OIL SEAL GUIDE Used for installing camshaft oil seal for DOHC engine.
  • Page 34 TOOL NUMBER DESCRIPTION REMARKS 24082AA230 CARTRIDGE Troubleshooting for electrical systems. ST24082AA230 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 2.

  • Page 35: Compression

    Compression MECHANICAL 2. Compression Australia model (Except for STi model) Standard A: INSPECTION 1.108 — 1,304 kPa (11 — 13 kgf/cm , 161 — 189 psi) CAUTION: Limit After warming-up, engine becomes very hot. Be 951 kPa (10 kgf/cm , 138 psi) careful not to burn yourself during measure- Difference between cylinders ment.

  • Page 36: Idle Speed

    4) Insert the cartridge to SUBARU SELECT MONI- TOR. 5) Connect the SUBARU SELECT MONITOR to data link connector. 6) Turn the ignition switch to ON, and SUBARU SELECT MONITOR switch to ON. 7) Select the {2. Each System Check} in Main Menu.

  • Page 37: Ignition Timing

    4) Insert the cartridge to SUBARU SELECT MONI- TOR. 5) Connect the SUBARU SELECT MONITOR to data link connector. 6) Turn the ignition switch to ON, and SUBARU SELECT MONITOR switch to ON. 7) Select the {2. Each System Check} in Main Menu.

  • Page 38: 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 the 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 39: Engine Oil Pressure

    Engine Oil Pressure MECHANICAL 6. Engine Oil Pressure A: INSPECTION 1) Remove the oil pressure switch from engine cyl- inder block. <Ref. to LU(H4DOTC)-18, REMOVAL, Oil Pressure Switch.> 2) Connect the oil pressure gauge hose to cylinder block. 3) Connect the battery ground cable to battery. FU-00009 4) Start the engine, and then measure the oil pres- sure.

  • Page 40: Fuel Pressure

    Fuel Pressure MECHANICAL 7. Fuel Pressure 6) Measure the fuel pressure while disconnecting the pressure regulator vacuum hose from intake A: INSPECTION manifold. CAUTION: Fuel pressure: Before removing the fuel pressure gauge, re- Standard; 284 — 314 kPa (2.9 — 3.2 kgf/cm lease the fuel pressure.

  • Page 41: Valve Clearance

    Valve Clearance MECHANICAL 8. Valve Clearance 10) When inspecting the #2 and #4 cylinders: (1) Disconnect the battery cable, and then re- A: INSPECTION move the battery and battery carrier. Inspection and adjustment of the valve clearance should be performed while engine is cold. 1) Set the vehicle on a lift.
  • Page 42 Valve Clearance MECHANICAL (5) Move the washer tank upward. NOTE: If the measured value is not within specification, take notes of the value in order to adjust the valve clearance later on. ( A ) ME-00017 (6) Disconnect the ignition coil connector. (7) Remove the ignition coil.
  • Page 43 Valve Clearance MECHANICAL (3) Set the arrow mark on camshaft sprocket to 3) Remove the valve lifter. position shown in the figure, and then measure 4) Measure the thickness of valve lifter with a mi- the #1 cylinder exhaust valve and #4 cylinder in- crometer.
  • Page 44 Valve Clearance MECHANICAL Part No. Thickness mm (in) Part No. Thickness mm (in) 13228 AB391 4.97 (0.1957) 13228 AB901 5.39 (0.2122) 13228 AB401 4.98 (0.1961) 13228 AB911 5.41 (0.2123) 13228 AB411 4.99 (0.1965) 13228 AB921 5.43 (0.2138) 13228 AB421 5.00 (0.1969) 13228 AB931 5.45 (0.2146) 13228 AB431...

  • Page 45: Engine Assembly

    Engine Assembly MECHANICAL 9. Engine Assembly 10) Remove the intercooler. <Ref. to IN(H4DOTC)- 10, REMOVAL, Intercooler.> A: REMOVAL 11) Disconnect the following connectors and cable. 1) Set the vehicle on a lift. (1) Engine harness connector 2) Open the front hood fully, and then support with the hood stay.
  • Page 46 Engine Assembly MECHANICAL (5) Accelerator cable (MT model) (2) Disconnect the power steering switch con- nector. ME-00031 ME-00035 (6) Clutch release spring (MT model) (3) Remove the pipe with bracket from intake manifold. ME-00032 12) Disconnect the following hoses. ME-00036 (1) Brake booster vacuum hose (4) Remove the power steering pump from en- gine.
  • Page 47 Engine Assembly MECHANICAL (6) Place the power steering pump on right side (2) Remove the plug using a 10 mm hexagon wheel apron. wrench. ME-00039 ME-00042 14) Lift-up the vehicle. (3) Screw the 6 mm dia. bolt into release fork shaft, and remove it.
  • Page 48 Engine Assembly MECHANICAL (4) Remove the other bolts while rotating the 25) Support the engine with a lifting device and engine using socket wrench. wire ropes. ME-00044 ME-00047 26) Support the transmission with a garage jack. 22) Remove the pitching stopper. NOTE: Before moving the engine away from transmission, check to be sure no work has been overlooked.
  • Page 49 Engine Assembly MECHANICAL (3) Remove the bolts which hold the right upper (3) Install the release fork into release bearing side of transmission to engine. tab. ME-00050 ME-00052 28) Remove the engine from vehicle. (A) Release fork (1) Slightly raise the engine. (B) Release bearing (2) Raise the transmission with garage jack.
  • Page 50 Engine Assembly MECHANICAL Tightening torque: CAUTION: 50 N·m (5.1 kgf-m, 36.9 ft-lb) Make sure the cutout portion of release fork shaft contacts spring pin. ME-00050 ME-00054 5) Remove the lifting device and wire ropes. 6) Remove the garage jack. (A) Release fork (B) Release shaft (C) Spring pin (6) Tighten the plug.
  • Page 51 Engine Assembly MECHANICAL (2) Tighten other bolts while rotating the engine (2) Install the power steering pump. by using ST. Tightening torque: CAUTION: 20.1 N·m (2.05 kgf-m, 14.8 ft-lb) Be careful not to drop bolts into the torque con- verter clutch housing. ST 499977300 CRANKSHAFT PULLEY WRENCH...
  • Page 52 Engine Assembly MECHANICAL Tightening torque: (2) Install the air cleaner element and air clean- er upper cover. 50 N·m (5.1 kgf-m, 36.9 ft-lb) (3) Install the engine harness connector brack- (4) Install the filler hose to air cleaner case. 24) Install the A/C pressure hoses. NOTE: Use new O-rings.

  • Page 53: Engine Mounting

    Engine Mounting MECHANICAL 10.Engine Mounting A: REMOVAL 1) Remove engine assembly. <Ref. ME(H4DOTC)-44, 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 54: 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 499817000 ENGINE STAND ME-00057 2) In this section the procedures described under each index are all connected and stated in order.

  • Page 55: V-Belt

    V-belt MECHANICAL 12.V-belt 4) Remove the A/C belt tensioner. A: REMOVAL 1. FRONT SIDE BELT 1) Remove the V-belt cover. ME-00061 B: INSTALLATION NOTE: Wipe off any oil or water on the belt and pulley. ME-00708 1. FRONT SIDE BELT 2) Loosen the lock bolt (A).
  • Page 56 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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