Subaru 2001 IMPREZA User manual

FUJI HEAVY INDUSTRIES LTD. G1830GE2
2001 IMPREZA SERVICE MANUAL QUICK REFERENCE INDEX
ENGINE 1 SECTION
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(SOHC)
EMISSION CONTROL
(AUX. EMISSION CONTROL DEVICES) EC(SOHC)
INTAKE (INDUCTION) IN(SOHC)
MECHANICAL ME(SOHC)
EXHAUST EX(SOHC)
COOLING CO
LUBRICATION LU
SPEED CONTROL SYSTEMS SP
IGNITION IG(SOHC)
STARTING/CHARGING SYSTEMS SC
ENGINE (DIAGNOSTICS) EN(SOHC)

MECHANICAL ME(SOHC)
Page
1. General Description ....................................................................................2
2. Compression.............................................................................................23
3. Idle Speed.................................................................................................24
4. Ignition Timing...........................................................................................25
5. Intake Manifold Vacuum............................................................................26
6. Engine Oil Pressure..................................................................................27
7. Fuel Pressure............................................................................................28
8. Valve Clearance........................................................................................29
9. Engine Assembly ......................................................................................32
10. Engine Mounting.......................................................................................40
11. Preparation for Overhaul...........................................................................41
12. V-belt.........................................................................................................42
13. Crankshaft Pulley......................................................................................44
14. Belt Cover .................................................................................................45
15. Timing Belt Assembly................................................................................46
16. Camshaft Sprocket....................................................................................51
17. Crankshaft Sprocket..................................................................................53
18. Valve Rocker Assembly............................................................................54
19. Camshaft...................................................................................................56
20. Cylinder Head Assembly...........................................................................60
21. Cylinder Block...........................................................................................68
22. Engine Trouble in General........................................................................88
23. Engine Noise.............................................................................................94

ME(SOHC)-2
MECHANICAL GENERAL DESCRIPTION
1. General Description
A: SPECIFICATIONS
NOTE:
STD: Standard I.D.: Inner Diameter O.D.: Outer
Diameter US: Undersize OS: Oversize
Engine
Model 1600 cc 2000 cc
Type Horizontally opposed, liquid cooled, 4-cylinder, 4-stroke gasoline
engine
Valve arrangement Belt driven, single over-head camshaft, 4-valve/cylinder
Bore x Stroke mm (in) 87.9 x 65.8 (3.46 x 2.591) 92 x 75 (3.62 x 2.95)
Displacement cm3(cu in) 1,597 (97.45) 1,994 (121.67)
Compression ratio 10.0
Compression pres-
sure (at 200 —300
rpm) kPa (kg/cm2, psi) 1,020 —1,275 (10.4 —13.0, 148 —185)
Number of piston rings Pressure ring: 2, Oil ring: 1
Intake valve timing Opening 10°BTDC 4°BTDC
Closing 46°ABDC 48°ABDC
Exhaust valve timing Opening 42°BBDC 48°BBDC
Closing 10°ATDC 4°ATDC
Valve clearance Intake mm (in) 0.20±0.02 (0.0079±0.0008)
Exhaust mm (in) 0.25±0.02 (0.0098±0.0008)
Idling speed[Atneutral position
on MT, or “P”or “N”position on
AT] rpm 700±100 (No load)
850±100 (A/C switch ON)
Firing order 1 →3 →2 →4
Ignition timing BTDC/rpm 5°±10°/700 10°±10°/700
Belt ten-
sioner
adjuster Protrusion of adjuster rod 5.2 —6.2 mm (0.205 —0.244 in)
Belt ten-
sioner
Spacer O.D. 17.955 —17.975 mm (0.7069 —0.7077 in)
Tensioner bush I.D. 18.00 —18.08 mm (0.7087 —0.7118 in)
Clearance between spacer and bush STD 0.025 —0.125 mm (0.0010 —0.0049 in)
Limit 0.175 mm (0.0069 in)
Side clearance of spacer STD 0.20 —0.55 mm (0.0079 —0.0217 in)
Limit 0.81 mm (0.0319 in)
Valve
rocker arm Clearance between shaft and arm STD 0.020 —0.054 mm (0.0008 —0.0021 in)
Limit 0.10 mm (0.0039 in)

ME(SOHC)-3
MECHANICAL
GENERAL DESCRIPTION
Camshaft
Bend limit 0.020 mm (0.0008 in)
Thrust clearance STD 0.030 —0.090 mm (0.0012 —0.0035 in)
Limit 0.11 mm (0.0043 in)
Cam lobe height
1600 cc Intake STD 39.378 —39.478 mm (1.5503 —1.5542 in)
Limit 39.278 mm (1.5464 in)
Exhaust STD 39.565 —39.665 mm (1.5577 —1.5616 in)
Limit 39.465 mm (1.5537 in)
2000 cc Intake STD 38.732 —38.832 mm (1.5249 —1.5288 in)
Limit 38.632 mm (1.5209 in)
Exhaust STD 39.257 —39.357 mm (1.5455 —1.5495 in)
Limit 39.157 mm (1.5416 in)
Camshaft journal O.D. 31.928 —31.945 mm (1.2570 —1.2577 in)
Camshaft journal hole I.D. 32.000 —32.018 mm (1.2598 —1.2605 in)
Oil clearance STD 0.055 —0.090 mm (0.0022 —0.0035 in)
Limit 0.10 mm (0.0039 in)
Cylinder
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 set
Refacing angle 90°
Contacting width Intake STD 1.0 mm (0.039 in)
Limit 1.7 mm (0.067 in)
Exhaust STD 1.4 mm (0.055 in)
Limit 2.1 mm (0.083 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 (0.650 —0.669 in)
Valve
Head edge thickness Intake STD 1.0 mm (0.039 in)
Limit 0.6 mm (0.024 in)
Exhaust STD 1.2 mm (0.047 in)
Limit 0.6 mm (0.024 in)
Stem diameter Intake 5.950 —5.965 mm (0.2343 —0.2348 in)
Exhaust 5.945 —5.960 mm(0.2341 —0.2346 in)
Stem oil clearance STD 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)
Overall length Intake 120.6 mm (4.75 in)
Exhaust 121.7 mm (4.79 in)
Valve
spring
Free length 54.30 mm (2.1378 in)
Squareness 2.5°, 2.4 mm (0.094 in)
Tension/spring height 218.7 —242.5 N (22.3 —24.7 kgf, 49.2 —54.5 lb)/45.0 mm (1.772 in) 526.6 —581.6 N (53.7 —59.3 kgf, 118.4
—130.8 lb)/34.7 mm (1.366 in)

ME(SOHC)-4
MECHANICAL GENERAL DESCRIPTION
Cylinder
block
Surface warpage limit (mating with cylinder head) 0.05 mm (0.0020 in)
Surface grinding limit 0.1 mm (0.004 in)
Cylinder bore 1600 cc STD A 87.905 —87.915 mm (3.4608 —3.4612 in)
B 87.895 —87.905 mm (3.4604 —3.4608 in)
2000 cc STD A 92.005 —92.015 mm (3.6222 —3.6226 in)
B 91.995 —92.005 mm (3.6218 —3.6222 in)
Taper STD 0.015 mm (0.0006 in)
Limit 0.050 mm (0.0020 in)
Out-of-roundness STD 0.010 mm (0.0004 in)
Limit 0.050 mm (0.0020 in)
Piston clearance STD 0.010 —0.030 mm (0.0004 —0.0012 in)
Limit 0.050 mm (0.0020 in)
Enlarging (boring) limit 0.5 mm (0.020 in)
Piston Outer diameter
1600 cc
STD A 87.885 —87.895 mm (3.4600 —3.4604 in)
B 87.875 —87.885 mm (3.4596 —3.4600 in)
0.25 mm (0.0098 in)
OS 88.125 —88.135 mm (3.4695 —3.4699 in)
0.50 mm (0.0197 in)
OS 88.375 —88.385 mm (3.4793 —3.4797 in)
2000 cc
STD A 91.985 —91.995 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)
Standard inner diameter of piston pin hole 23.000 —23.006 mm (0.9055 —0.9057 in)
Piston pin
Outer diameter 22.994 —23.000 mm (0.9053 —0.9055 in)
Standard clearance between piston pin and hole in pis-
ton 0.004 —0.008 mm (0.0002 —0.0003 in)
Degree of fit Piston pin must be fitted into position with thumb at 20°C
(68°F).
Piston ring
Piston ring gap
Top ring STD 0.20 —0.35 mm (0.0079 —0.0138 in)
Limit 1.0 mm (0.039 in)
Second
ring STD 0.35 —0.50 mm (0.0138 —0.0197 in)
Limit 1.0 mm (0.039 in)
Oil ring STD 0.20 —0.70 mm (0.0079 —0.0276 in)
Limit 1.5 mm (0.059 in)
Clearance
between piston
ring and piston
ring groove
Top ring STD 0.040 —0.080 mm (0.0016 —0.0031 in)
Limit 0.15 mm (0.0059 in)
Second
ring STD 0.030 —0.070 mm (0.0012 —0.0028 in)
Limit 0.15 mm (0.0059 in)
Connecting
rod
Bend twist per 100 mm (3.94
in) in length Limit 0.10 mm (0.0039 in)
Side clearance STD 0.070 —0.330 mm (0.0028 —0.0130 in)
Limit 0.4 mm (0.016 in)
Connecting
rod bearing
Oil clearance STD 0.010 —0.038 mm (0.0004 —0.0015 in)
Limit 0.05 mm (0.0020 in)
Thickness at center portion
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)

ME(SOHC)-5
MECHANICAL
GENERAL DESCRIPTION
Connecting
rod bushing Clearance between piston pin and bushing STD 0 —0.022 mm (0 —0.0009 in)
Limit 0.030 mm (0.0012 in)
Crankshaft
Bend limit 0.035 mm (0.0014 in)
Crank pin and
crank journal Out-of-roundness 0.020 mm (0.0008 in) or less
Grinding limit 0.250 mm (0.0098 in)
Crank pin outer
diameter
1600 cc
STD 47.984 —48.000 mm (1.8880 —1.8898)
0.03 mm (0.0012 in)
US 47.954 —47.970 mm (1.8879 —1.8886)
0.05 mm (0.0020 in)
US 47.934 —47.950 mm (1.8872 —1.8878)
0.25 mm (0.0098 in)
US 47.734 —47.750 mm (1.8793 —1.8799)
2000 cc
STD 51.984 —52.000 mm (2.0466 —2.0472 in)
0.03 mm (0.0012 in)
US 51.954 —51.970 mm (2.0454 —2.0461 in)
0.05 mm (0.0020 in)
US 51.934 —51.950 mm (2.0446 —2.0453 in)
0.25 mm (0.0098 in)
US 51.734 —51.750 mm (2.0368 —2.0374 in)
Crank 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 in)
US 59.742 —59.758 mm (2.3520 —2.3527 in)
Thrust clearance STD 0.030 —0.115 mm (0.0012 —0.0045 in)
Limit 0.25 mm (0.0098 in)
Oil clearance STD 0.010 —0.030 mm (0.0004 —0.0012 in)
Limit 0.040 mm (0.0016 in)
Crankshaft
bearing Crankshaft bear- ing thickness
#1, #3
STD 1.998 —2.011 mm (0.0787 —0.0792 in)
0.03 mm (0.0012 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)

ME(SOHC)-6
MECHANICAL GENERAL DESCRIPTION
B: COMPONENT
1. TIMING BELT
T5
T4
T1
T1
T6
T5
(5)
(6)
(8)
(9)
(11)
(10)
(14)
(15)
(12)
(13)
(7)
(4)
(1)
(2)
(3)
T1
T2
T1
EN0581
(1) Belt cover No. 2 (RH) (9) Automatic belt tension adjuster
ASSY Tightening torque: N·m (kgf-m, ft-lb)
(2) Timing belt guide (MT vehicles
only) T1: 5 (0.5, 3.6)
(10) Belt idler No. 2 T2: 9.8 (1.0, 7.2)
(3) Crankshaft sprocket (11) Camshaft sprocket No. 2 T3: 25 (2.5, 18.1)
(4) Belt cover No. 2 (LH) (12) Timing belt T4: 39 (4.0, 28.9)
(5) Camshaft sprocket No. 1 (13) Front belt cover T5: 78 (8.0, 57.9)
(6) Belt idler (No. 1) (14) Belt cover (LH) T6: 127 (13.0, 94)
(7) Tensioner bracket (15) Crankshaft pulley
(8) Belt idler (No. 2)

ME(SOHC)-7
MECHANICAL
GENERAL DESCRIPTION
2. CYLINDER HEAD AND CAMSHAFT
B2M1954D
(1) Rocker cover (RH) (11) Cylinder head (LH) Tightening torque: N·m (kgf-m, ft-lb)
(2) Intake valve rocker ASSY (12) Camshaft (LH) T1: <Ref. to ME(SOHC)-60,
Installation, Cylinder Head
Assembly.>
(3) 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 pipe 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(SOHC)-8
MECHANICAL GENERAL DESCRIPTION
3. VALVE ROCKER ASSEMBLY
B2M1956A
(1) Intake valve rocker arm (6) Intake rocker shaft Tightening torque: N·m (kgf-m, ft-lb)
(2) Valve rocker nut (7) Exhaust rocker shaft T1: 5 (0.5, 3.6)
(3) Valve rocker adjust screw (8) Exhaust valve rocker arm T2: 10 (1.0, 7.2)
(4) Spring T3: 25 (2.5, 18.1)
(5) Rocker shaft support

ME(SOHC)-9
MECHANICAL
GENERAL DESCRIPTION
4. CYLINDER HEAD AND VALVE ASSEM-
BLY
B2M1955A
(1) Exhaust valve (5) Intake valve oil seal (9) Exhaust valve guide
(2) Intake valve (6) Valve spring (10) Exhaust valve spring seat
(3) Intake valve guide (7) Retainer (11) Exhaust valve oil seal
(4) Intake valve spring seat (8) Retainer key