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FUJI HEAVY INDUSTRIES LTD.

G1870GE2

2004 IMPREZA SERVICE MANUAL

QUICK REFERENCE INDEX

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.

FUEL INJECTION (FUEL SYSTEMS)

FU(H4SO)

EMISSION CONTROL 
(AUX. EMISSION CONTROL DEVICES)

EC(H4SO)

INTAKE (INDUCTION)

IN(H4SO)

MECHANICAL

ME(H4SO)

EXHAUST

EX(H4SO)

COOLING

CO(H4SO)

LUBRICATION

LU(H4SO)

SPEED CONTROL SYSTEMS

SP(H4SO)

IGNITION

IG(H4SO)

STARTING/CHARGING SYSTEMS

SC(H4SO)

ENGINE (DIAGNOSTICS)

EN(H4SO)(diag)

FUEL INJECTION (FUEL SYSTEMS)

FU(H4SOw/oOBD)

EMISSION CONTROL 
(AUX. EMISSION CONTROL DEVICES)

EC(H4SOw/oOBD)

INTAKE (INDUCTION)

IN(H4SOw/oOBD)

MECHANICAL

ME(H4SOw/oOBD)

EXHAUST

EX(H4SOw/oOBD)

COOLING

CO(H4SOw/oOBD)

Summary of Contents for Impreza 2004

Page 1: ...e 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 FUEL INJECTION FUEL SYSTEMS FU H4SO EMISSION CONTROL AUX EMISSION CONTROL DEVICES EC H4SO INTAKE INDUCTION IN H4SO MECHANI...

Page 2: ...CE MANUAL QUICK REFERENCE INDEX ENGINE SECTION 1 G1870GE2 LUBRICATION LU H4SOw oOBD SPEED CONTROL SYSTEMS SP H4SOw oOBD IGNITION IG H4SOw oOBD STARTING CHARGING SYSTEMS SC H4SOw oOBD ENGINE DIAGNOSTICS EN H4SOw oOBD diag ...

Page 3: ...8 Valve Clearance 32 9 Engine Assembly 34 10 Engine Mounting 41 11 Preparation for Overhaul 42 12 V belt 43 13 Crankshaft Pulley 45 14 Timing Belt Cover 47 15 Timing Belt Assembly 48 16 Camshaft Sprocket 53 17 Crankshaft Sprocket 55 18 Valve Rocker Assembly 56 19 Camshaft 58 20 Cylinder Head Assembly 62 21 Cylinder Block 68 22 Engine Trouble in General 89 23 Engine Noise 95 ...

Page 4: ... 48 BBDC 50 BBDC Closing 10 ATDC 4 ATDC 6 ATDC Valve clearance Intake mm in 0 20 0 04 0 0079 0 0016 Exhaust mm in 0 25 0 04 0 0098 0 0016 Idling speed At neutral position on MT or P or N position on AT rpm With OBD 650 100 No load 850 100 A C ON Without OBD 700 100 No load 850 100 A C ON 650 100 No load 850 100 A C ON Firing order 1 3 2 4 Ignition timing BTDC rpm With OBD 5 10 650 Without OBD 5 10...

Page 5: ...head Surface warpage limit 0 05 mm 0 0020 in Surface grinding limit 0 1 mm 0 004 in Standard height 97 5 mm 3 84 in Valve seat Refacing angle 90 Contacting width Intake STD 1 0 mm 0 039 in Limit 1 7 mm 0 067 in Exhaust STD 1 5 mm 0 059 in Limit 2 2 mm 0 087 in Valve guide Inner diameter 6 000 6 012 mm 0 2362 0 2367 in Protrusion above head Intake 20 0 20 5 mm 0 787 0 807 in Exhaust 16 5 17 0 mm 0 ...

Page 6: ... mm 3 6214 3 6218 in B 91 975 91 985 mm 3 6211 3 6214 in 0 25 mm 0 0098 in OS 92 225 92 235 mm 3 6309 3 6313 in 0 50 mm 0 0197 in OS 92 475 92 485 mm 3 6407 3 6411 in 2 5 L STD 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 OS 99 725 99 735 mm 3 9262 3 9266 in 0 50 mm 0 0197 in OS 99 975 99 985 mm 3 9360 3 9364 in Standard inner diameter of piston pin hol...

Page 7: ... 0020 in Thickness at cen ter portion 1 6 L 2 0 L STD 1 492 1 501 mm 0 0587 0 0591 in 0 03 mm 0 0012 in US 1 510 1 513 mm 0 0594 0 0596 in 0 05 mm 0 0020 in US 1 520 1 523 mm 0 0598 0 0600 in 0 25 mm 0 0098 in US 1 620 1 623 mm 0 0638 0 0639 in 2 5 L STD 1 490 1 502 mm 0 0587 0 0591 in 0 03 mm 0 0012 in US 1 504 1 512 mm 0 0592 0 0595 in 0 05 mm 0 0020 in US 1 514 1 522 mm 0 0596 0 0599 in 0 25 mm...

Page 8: ...journal outer diameter 1 3 STD 59 992 60 008 mm 2 3619 2 3625 in 0 03 mm 0 0012 in US 59 962 59 978 mm 2 3607 2 3613 in 0 05 mm 0 0020 in US 59 942 59 958 mm 2 3599 2 3605 in 0 25 mm 0 0098 in US 59 742 59 758 mm 2 3520 2 3527 in 2 4 5 STD 59 992 60 008 mm 2 3619 2 3625 in 0 03 mm 0 0012 in US 59 962 59 978 mm 2 3607 2 3613 in 0 05 mm 0 0020 in US 59 942 59 958 mm 2 3599 2 3605 in 0 25 mm 0 0098 i...

Page 9: ... in US 2 017 2 020 mm 0 0794 0 0795 in 0 05 mm 0 0020 in US 2 027 2 030 mm 0 0798 0 0799 in 0 25 mm 0 0098 in US 2 127 2 130 mm 0 0837 0 0839 in 2 4 5 STD 2 000 2 013 mm 0 0787 0 0793 in 0 03 mm 0 0012 in US 2 019 2 022 mm 0 0795 0 0796 in 0 05 mm 0 0020 in US 2 029 2 032 mm 0 0799 0 0800 in 0 25 mm 0 0098 in US 2 129 2 132 mm 0 0838 0 0839 in ...

Page 10: ... 7 2 4 Timing belt cover No 2 LH 13 Front timing belt cover T3 25 2 5 18 1 5 Camshaft sprocket No 1 14 Timing belt cover LH T4 39 4 0 28 9 6 Belt idler No 1 15 Crankshaft pulley 1 6 L and 2 0 L model T5 78 8 0 57 9 7 Tensioner bracket T6 Ref to ME H4SO 45 INSTALLATION Crankshaft Pulley 8 Belt idler No 2 16 Crankshaft pulley 2 5 L model 9 Automatic belt tension adjuster ASSY ME 00376 T5 T4 T1 T1 T6...

Page 11: ...Exhaust valve rocker ASSY 13 Camshaft cap LH 4 Camshaft cap RH 14 Oil filler cap 5 Oil seal 15 Gasket T2 5 0 5 3 6 6 Camshaft RH 16 Oil filler duct T3 10 1 0 7 2 7 Plug 17 O ring T4 18 1 8 13 0 8 Spark plug pipe gasket 18 Rocker cover LH T5 25 2 5 18 1 9 Cylinder head RH 19 Stud bolt T6 6 4 0 65 4 7 10 Cylinder head gasket ME 00186 17 10 11 19 12 13 14 15 16 18 2 3 8 5 1 2 3 4 8 6 7 8 7 9 10 19 T2...

Page 12: ... shaft support Tightening torque N m kgf m ft lb 2 Valve rocker nut 6 Intake rocker shaft T1 5 0 5 3 6 3 Valve rocker adjust screw 7 Exhaust rocker shaft T2 10 1 0 7 2 4 Spring 8 Exhaust valve rocker arm T3 25 2 5 18 1 ME 00187 2 2 2 3 3 3 3 4 5 4 1 2 6 8 7 1 2 2 3 3 4 4 1 5 1 T2 T1 T3 T1 T2 T3 T2 T2 ...

Page 13: ...iption 4 CYLINDER HEAD AND VALVE ASSEMBLY 1 Exhaust valve 4 Valve spring seat 7 Retainer 2 Intake valve 5 Intake valve oil seal 8 Retainer key 3 Valve guide 6 Valve spring 9 Exhaust valve oil seal ME 00760 2 2 6 6 3 3 4 4 5 9 7 8 7 8 1 1 ...

Page 14: ... T5 Ref to ME H4SO 73 INSTALLATION Cylinder Block 7 Oil pump 20 Metal gasket 8 Front oil seal 21 Oil level gauge guide 9 Rear oil seal 22 Water pump sealing T6 70 7 1 50 6 10 O ring 23 Oil filter T7 First 12 1 2 8 7 Second 12 1 2 8 7 11 Service hole cover 24 Gasket 12 Cylinder block LH 25 Water pump hose T8 16 1 6 11 6 13 Water pump 26 Plug T9 44 4 5 33 T10 25 2 5 18 1 T11 45 4 6 33 3 FU 01016 14 ...

Page 15: ...ME H4SO 13 MECHANICAL General Description 6 CRANKSHAFT AND PISTON ME 00190 T1 T1 9 1 16 17 16 17 6 5 4 3 2 12 11 10 7 9 9 8 6 5 4 15 18 9 8 10 12 11 7 13 12 14 T2 T2 ...

Page 16: ...model 10 Connecting rod bolt 18 Crankshaft bearing 5 3 Drive plate AT model 11 Connecting rod 4 Top ring 12 Connecting rod bearing Tightening torque N m kgf m ft lb 5 Second ring 13 Connecting rod cap T1 45 4 6 33 3 6 Oil ring 14 Crankshaft T2 72 7 3 52 8 7 Piston 15 Woodruff key 8 Piston pin 16 Crankshaft bearing 1 3 ...

Page 17: ...ECHANICAL General Description 7 ENGINE MOUNTING 1 Front cushion rubber 2 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 00413 T2 T1 T1 T3 T3 2 2 1 1 T2 ...

Page 18: ...r to assembly Be careful not to let oil grease or coolant contact the timing belt clutch disc and flywheel All removed parts if to be reused should be re installed in the original positions and directions Bolts nuts and washers should be replaced with new ones as required Even if necessary inspections have been made in advance proceed with assembly work while making rechecks Remove or install engi...

Page 19: ...Without printer Spanish 22771AA090 Without printer 498267800 CYLINDER HEAD TABLE Used for replacing valve guides Used for removing and installing valve springs 498277200 STOPPER SET Used for installing automatic transmission assem bly to engine 498457000 ENGINE STAND ADAPTER RH Used with ENGINE STAND 499817000 ILLUSTRATION TOOL NUMBER DESCRIPTION REMARKS ST22771AA030 ST 498267800 ST 498277200 ST 4...

Page 20: ...os ening and tightening crankshaft pulley bolt etc 498547000 OIL FILTER WRENCH Used for removing and installing oil filter For oil filter of outer diameter 80 mm 3 15 in 18332AA000 OIL FILTER WRENCH Used for removing and installing oil filter For oil filter of outer diameter 68 mm 2 68 in ILLUSTRATION TOOL NUMBER DESCRIPTION REMARKS ST 498457100 ST 498497100 ST 498547000 ST18332AA000 ...

Page 21: ...STON GUIDE Used for installing piston in cylinder 2 0 L model 498747300 PISTON GUIDE Used for installing piston in cylinder 2 5 L model 498857100 VALVEOIL SEAL GUIDE Used for press fitting of intake and exhaust valve guide oil seals ILLUSTRATION TOOL NUMBER DESCRIPTION REMARKS ST 498747000 ST 398744300 ST 498747300 ST 498857100 ...

Page 22: ...REMOVER INSTALLER Used for removing and installing connecting rod bushing 499057000 TORX PLUS Used for removing flywheel Dual mass flywheel 499587200 CRANKSHAFT OIL SEAL INSTALLER Used for installing crankshaft oil seal Used with CRANKSHAFT OIL SEAL GUIDE 499597100 ILLUSTRATION TOOL NUMBER DESCRIPTION REMARKS ST 499017100 ST 499037100 ST 499057000 ST 499587200 ...

Page 23: ...9597000 499587700 CAMSHAFT OIL SEAL INSTALLER Used for installing cylinder head plug 499097700 PISTON PIN REMOVER ASSY Used for removing piston pin 499207400 CAMSHAFT SPROCKET WRENCH Used for removing and installing camshaft sprocket RH side ILLUSTRATION TOOL NUMBER DESCRIPTION REMARKS ST 499587500 ST 499587700 ST 499097700 ST 499207400 ...

Page 24: ...ing oil pump oil seal 499597000 OIL SEAL GUIDE Used for installing camshaft oil seal Used with CAMSHAFT OIL SEAL INSTALLER 499587500 499597100 CRANKSHAFT OIL SEAL GUIDE Used for installing crankshaft oil seal Used with CRANKSHAFT OIL SEAL INSTALLER 499587200 ILLUSTRATION TOOL NUMBER DESCRIPTION REMARKS ST 499497000 ST 499587100 ST 499597000 ST 499597100 ...

Page 25: ...g valve spring 499767200 VALVE GUIDE REMOVER Used for removing valve guides 499767400 VALVE GUIDE REAMER Used for reaming valve guides 499767700 VALVE GUIDE ADJUSTER Used for installing valve guide Intake side ILLUSTRATION TOOL NUMBER DESCRIPTION REMARKS ST 499718000 ST 499767200 ST 499767400 ST 499767700 ...

Page 26: ...98457000 LH 498457100 499977400 CRANKSHAFT PULLEY WRENCH Used for stopping rotation of crankshaft pulley when loosening and tightening crankshaft pulley bolts 1 6 L and 2 0 L model 499977100 CRANKSHAFT PULLEY WRENCH Used for stopping rotation of crankshaft pulley when loosening and tightening crankshaft pulley bolts 2 5 L model ILLUSTRATION TOOL NUMBER DESCRIPTION REMARKS ST 499767700 ST 499817100...

Page 27: ...rom the vehi cle V belt Timing Belt Valve Rocker Assembly Camshaft Cylinder Head 499987500 CRANKSHAFT SOCKET Used for rotating crankshaft 499897200 PISTON CIR CLIP PLIERS Used for removing and installing piston pin circlip TOOL NAME REMARKS Compression Gauge Used for measuring compression Tachometer Secondary pick up type Used for measuring idle speed Timing Light Used for measuring ignition timin...

Page 28: ...Fully open the throttle valve 6 Check the starter motor for satisfactory perfor mance 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 less than 18 mm 0 71 in long 8 Crank the engine by means of starter motor and then read the maximum value on the gauge when the poin...

Page 29: ...d 5 When using the tachometer Secondary pick up type 1 Attach the pick up clip to No 1 cylinder spark plug cord 2 Start the engine and then read the engine idle speed NOTE When using the OBD II general scan tool care fully read its operation manual This ignition system provides simultaneous igni tion for 1 and 2 plugs It must be noted that some tachometers may register twice that of actual en gine...

Page 30: ...linder spark plug cord and illuminate the timing mark with timing light 3 Start the engine at idle speed and check the ig nition timing Ignition timing BTDC rpm 1 6 L model With OBD 5 10 650 Without OBD 5 10 700 2 0 L model With OBD 10 10 650 Without OBD 10 10 700 2 5 L model MT 10 10 650 AT 15 10 650 If the timing is not correct check the ignition control system Refer to Engine Control System Ref...

Page 31: ...t lower than normal position This ten dency becomes more evident as engine temperature rises Leakage around intake manifold gasket or disconnection or damaged vacuum hose 2 When engine speed is reduced slowly from higher speed needle stops temporarily when it is lowering or becomes steady above normal position Back pressure too high or exhaust system clogged 3 Needle intermittently drops to positi...

Page 32: ...e at 5 000 rpm CAUTION If the oil pressure is out of specification check the oil pump oil filter and lubrication line Ref to LU H4SO 21 INSPECTION En gine Lubrication System Trouble in General If the oil pressure warning light is turned ON and oil pressure is in specification replace the oil pressure switch Ref to LU H4SO 21 IN SPECTION Engine Lubrication System Trouble in General NOTE The specifi...

Page 33: ...he fuel delivery hoses from fuel damper 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 cm2 41 46 psi 7 After connecting the pressure regulator vacuum hose measure the fuel pressure Fuel pressure...

Page 34: ...9 Set the 1 cylinder piston to top dead center of compression stroke by rotating crankshaft pulley clockwise using a socket wrench NOTE When arrow mark A on the camshaft sprocket LH comes exactly to the top 1 cylinder piston is brought to the top dead center of compression stroke 10 Measure the 1 cylinder valve clearance by us ing thickness gauge CAUTION Insert the thickness gauge A in as horizon ...

Page 35: ...ance 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 in as horizontal a direction 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 wit...

Page 36: ...er cap 6 Disconnect the ground cable from battery 7 Remove the air intake duct and air cleaner case Ref to IN H4SO 6 REMOVAL Air Intake Duct and Ref to IN H4SO 5 REMOVAL Air Cleaner Case 8 Remove the under cover 9 Remove the radiator from vehicle Ref to CO H4SO 19 REMOVAL Radiator 10 Disconnect the A C pressure hoses from A C compressor 11 Remove the air intake chamber stay MT MODEL AT MODEL 12 Di...

Page 37: ...ect the following hoses 1 Brake booster vacuum hose 2 Heater inlet outlet hose 14 Remove the power steering pump from brack et 1 Remove the resonator chamber 2 Loosen the lock bolt and slider bolt and then remove the front side V belt Ref to ME H4SO 43 FRONT SIDE BELT REMOV AL V belt 3 Remove the pipe with bracket A Generator connector and terminal B A C compressor connector FU 00826 ME 00208 A B ...

Page 38: ...move the nuts which install the front cushion rubber onto front crossmember 18 Separate the torque converter clutch from drive plate AT model 1 Lower the vehicle 2 Remove the service hole plug 3 Remove the bolts which hold the torque converter clutch to drive plate 4 Remove other bolts while rotating the en gine using socket wrench 19 Remove the pitching stopper 20 Disconnect the fuel delivery hos...

Page 39: ...move the bolts which hold the upper side of transmission to engine 24 Install the ST to torque converter clutch case AT model ST 498277200 STOPPER SET 25 Remove the engine from vehicle 1 Slightly raise the engine 2 Raise the transmission with garage jack 3 Move the engine horizontally until main shaft is withdrawn from clutch cover 4 Slowly move the engine away from engine compartment NOTE Be care...

Page 40: ... 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 model NOTE Be careful not to drop the ST into torque converter clutch case when removing ST ST 498277200 STOPPER SET 8 Install the starter Ref to SC H4SO 7 IN STALLATION Starter 9 Install the torque converter clutch onto drive plate AT model 1 Tighten the bolts ...

Page 41: ...adjust it Ref to ME H4SO 43 FRONT SIDE BELT IN STALLATION V belt 6 Install the resonator chamber Tightening torque 33 N m 3 4 kgf m 24 6 ft lb 11 Tighten the nuts which hold the 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 the front cushion rubber onto crossmember Tightening torque 85 N m 8 7 kgf m 63 ft lb NOTE Make sure the ...

Page 42: ...se and Tube 20 Install the radiator to vehicle Ref to CO H4SO 20 INSTALLATION Radiator 21 Install the air intake duct and air cleaner case Ref to IN H4SO 6 INSTALLATION Air Intake Duct and Ref to IN H4SO 5 INSTALLATION Air Cleaner Case 22 Install the under cover 23 Install battery in the vehicle and then connect the cables 24 Fill engine coolant Ref to CO H4SO 13 FILLING OF ENGINE COOLANT REPLACEM...

Page 43: ...ngine assembly Ref to 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: ... 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 pre viously in order to d...

Page 45: ...ON NOTE Wipe off any oil or water on the belt and pulley 1 FRONT SIDE BELT 1 Install a V belt C and tighten the slider bolt so as to obtain the specified belt tension Ref to ME H4SO 44 INSPECTION V belt 2 Tighten the lock bolt A 3 Tighten the slider bolt B Tightening torque Lock bolt A 25 N m 2 5 kgf m 18 1 ft lb Slider bolt B 8 N m 0 8 kgf m 5 9 ft lb 2 REAR SIDE BELT 1 Remove the A C belt tensio...

Page 46: ... installing new parts 740 880 N 75 90 kgf 166 198 lb At inspection 350 450 N 36 46 kgf 78 101 lb Belt tension without belt tension gauge A When installing new parts 7 9 mm 0 276 0 354 in At inspection 9 11 mm 0 354 0 433 in B When installing new parts 7 5 8 5 mm 0 295 0 335 in At inspection 9 0 10 0 mm 0 354 0 394 in A Front side belt B Rear side belt C P Crank pulley GEN Generator P S Power steer...

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