1997 SUBARU LEGACY engine

TROUBLE
Engine will not start.
Rough idle and engine stall
Low output, hesitation and poor acceleration
Surging
Engine does not return to idle.
Dieseling (Run-on)
After burning in exhaust system
Knocking
Excessive engine oil consumption
Excessive fuel consumption Starter does not turn.
Initial combustion does not occur.
Initial combustion occurs.
Engine stalls after initial combustion.
INTAKE SYSTEM
2111 3Loosened or cracked intake air pipe
3111 3 1Loosened or cracked blow-by hose
31211 2Loosened or cracked vacuum hose
22222Defective intake manifold gasket
22222Defective throttle body gasket
322 2 2Defective PCV valve
222 323Loosened oil filler cap
3312 1Dirty air cleaner element
FUEL LINE
13 322Defective fuel pump and relay
33322Clogged fuel line
222233Lack of or insufficient fuel
BELT
222Defective
222322 22 2Defective timing
FRICTION
3Seizure of crankshaft and connecting rod bearing
3Seized camshaft
3Seized or stuck piston and cylinder
COMPRESSION
333222 23 2Incorrect valve clearance
333223 3 3Loosened spark plugs or defective gasket
333223 3 3Loosened cylinder head bolts or defective gasket
333223 2 2Improper valve seating
333333 3 13Defective valve stem
222223 3 3Worn or broken valve spring
333233 3 12Worn or stuck piston rings, cylinder and piston
222111 12 2Incorrect valve timing
222222Improper engine oil (low viscosity)
76
2-3DIAGNOSTICS
1. Engine Trouble in General

TROUBLE
Engine will not start.
Rough idle and engine stall
Low output, hesitation and poor acceleration
Surging
Engine does not return to idle.
Dieseling (Run-on)
After burning in exhaust system
Knocking
Excessive engine oil consumption
Excessive fuel consumption Starter does not turn.
Initial combustion does not occur.
Initial combustion occurs.
Engine stalls after initial combustion.
LUBRICATION SYSTEM
22 3 3Incorrect oil pressure
2Loosened oil pump attaching bolts and defective
gasket
2Defective oil filter seal
2Defective crankshaft oil seal
32Defective rocker cover gasket
2Loosened oil drain plug or defective gasket
2Loosened oil pan fitting bolts or defective oil pan
COOLING SYSTEM
33221Overheating
333Over cooling
OTHERS
113 3Malfunction of Evaporative Emission Control
System
21Stuck or damaged throttle valve
322 2Accelerator cable out of adjustment
77
2-3DIAGNOSTICS
1. Engine Trouble in General

2. Engine Noise
Type of sound Condition Possible cause
Regular clicking soundSound increases as engine
speed increases.Valve mechanism is defective.
Incorrect valve clearance
Worn valve rocker
Worn camshaft
Broken valve spring
Heavy and dull clankOil pressure is low.Worn crankshaft main bearing
Worn connecting rod bearing (big end)
Oil pressure is normal.Loose flywheel mounting bolts
Damaged engine mounting
High-pitched clank
(Spark knock)Sound is noticeable when
accelerating with an overload.Ignition timing advanced
Accumulation of carbon inside combustion chamber
Wrong spark plug
Improper gasoline
Clank when engine speed is
medium (1,000 to 2,000 rpm).Sound is reduced when fuel
injector connector of noisy
cylinder is disconnected.
(NOTE*)Worn crankshaft main bearing
Worn bearing at crankshaft end of connecting rod
Knocking sound when engine
is operating under idling speed
and engine is warm.Sound is reduced when fuel
injector connector of noisy
cylinder is disconnected.
(NOTE*)Worn cylinder liner and piston ring
Broken or stuck piston ring
Worn piston pin and hole at piston end of connecting rod
Sound is not reduced if each
fuel injector connector is
disconnected in turn. (NOTE*)Worn camshaft journal bore in crankcase
Squeaky sound—Insufficient generator lubrication
Rubbing sound—Defective generator brush and rotor contact
Gear scream when starting
engine—Defective ignition starter switch
Worn gear and starter pinion
Sound like polishing glass with
a dry cloth—Loose drive belt
Defective engine coolant pump shaft
Hissing sound—Loss of compression
Air leakage in air intake system, hoses, connections or
manifolds
Timing belt noise—Loose timing belt
Belt contacting case/adjacent part
Valve tappet noise—Incorrect valve clearance
NOTE*:
When disconnecting fuel injector connector, Malfunction Indicator Light (CHECK ENGINE light) illuminates and trouble code is stored in
ECM memory.
Therefore, carry out the CLEAR MEMORY MODE and INSPECTION MODE after connecting fuel injector connector. (Ref. to 2-7 On-Board
Diagnostics II System.)
78
2-3DIAGNOSTICS
2. Engine Noise

79
2-3DIAGNOSTICS
2. Engine Noise

1. Engine
A: SPECIFICATIONS
EngineModel2500 cc
TypeHorizontally opposed, liquid cooled, 4-cylinder, 4-stroke
gasoline engine
Valve arrangement Belt driven, double over-head camshaft, 4-valve/cylinder
Bore x Stroke mm (in) 99.5 x 79.0 (3.917 x 3.110)
Displacement cm
3(cu in) 2,457 (149.93)
Compression ratio9.5
Compression pressure
(at 200 — 300 rpm)
kPa (kg/cm
2, psi) rpmStandard 1,216 (12.4, 176) 350
Limit 941 (9.6, 137) 350
Number of piston rings Pressure ring: 2, Oil ring: 1
Intake valve timingOpening 6° BTDC
Closing 50° ABDC
Exhaust valve timingOpening Front: 54° BBDC, Rear: 30° BBDC (Position in degrees)
Closing Front: 10° ATDC, Rear: 10° ATDC (Position in degrees)
Valve clearanceIntake mm (in) 0.20±0.02 (0.0079±0.0008)
Exhaust mm (in) 0.25±0.02 (0.0098±0.0008)
Idling speed
[At neutral position on MT, or
“P” or “N” position on AT] rpm700±100 (No load)
850±50 (A/C switch ON)
Firing order1,3,2,4
Ignition timing BTDC/rpm 15°±8°/700 rpm
2
2-3bSPECIFICATIONS AND SERVICE DATA
1. Engine

B: SERVICE DATA
Belt
tension
adjusterProtrusion of adjuster rod 15.4—16.4 mm (0.606—0.646 in)
Belt ten-
sionerSpacer O.D. 16 mm (0.63 in)
Tensioner bush I.D. 16.16 mm (0.6362 in)
Clearance between spacer and bushSTD 0.117—0.180 mm (0.0046—0.0071 in)
Limit 0.230 mm (0.0091 in)
Side clearance of spacerSTD 0.37—0.54 mm (0.0146—0.0213 in)
Limit 0.8 mm (0.031 in)
CamshaftBend limit 0.020 mm (0.0008 in)
Thrust clearanceSTD 0.040—0.080 mm (0.0016—0.0031 in)
Limit 0.10 mm (0.0039 in)
Cam lobe heightIntakeSTD 42.20—42.30 mm (1.6614—1.6654 in)
Limit 42.04 mm (1.6551 in)
ExhaustSTDFront: 42.50—42.60 mm
Rear: 41.40—41.50 mm(1.6732—1.6772 in)
(1.6299—1.6339 in)
LimitFront: 42.34 mm
Rear: 41.24 mm(1.6669 in)
(1.6236 in)
Camshaft journal O.D.Front 31.946—31.963 mm (1.2577—1.2584 in)
Center 27.946—27.963 mm (1.1002—1.1009 in)
Rear 27.946—27.963 mm (1.1002—1.1009 in)
Camshaft journal hole I.D.Front 32.000—32.018 mm (1.2598—1.2605 in)
Center 28.000—28.018 mm (1.1024—1.1031 in)
Rear 28.000—28.018 mm (1.1024—1.1031 in)
Oil clearanceSTD 0.037—0.072 mm (0.0015—0.0028 in)
Limit 0.10 mm (0.0039 in)
Cylinder
headSurface warpage limit 0.05 mm (0.0020 in)
Surface grinding limit 0.3 mm (0.012 in)
Standard height 127.5 mm (5.02 in)
Valve seatRefacing angle 90°
Contacting widthIntakeSTD 1.0 mm (0.039 in)
Limit 1.7 mm (0.067 in)
ExhaustSTD 1.5 mm (0.059 in)
Limit 2.2 mm (0.087 in)
Valve
guideInner diameter 6.000—6.015 mm (0.2362—0.2368 in)
Protrusion above head 12.0—12.4 mm (0.472—0.488 in)
ValveHead edge thicknessIntakeSTD 1.2 mm (0.047 in)
Limit 0.8 mm (0.031 in)
ExhaustSTD 1.5 mm (0.059 in)
Limit 0.8 mm (0.031 in)
Stem diameterIntake 5.950—5.965 mm (0.2343—0.2348 in)
Exhaust 5.950—5.965 mm (0.2343—0.2348 in)
Stem oil clearanceSTDIntake 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 lengthIntake 105.9 mm (4.169 in)
Exhaust 106.2 mm (4.181 in)
STD: Standard I.D.: Inner Diameter O.D.: Outer Diameter
3
2-3bSPECIFICATIONS AND SERVICE DATA
1. Engine

Valve springFree length 48.04 mm (1.8913 in)
Squareness 2.5°, 2.1 mm (0.083 in)
Tension/spring height146.1—167.7 N
(14.9—17.1 kg, 32.9—37.7 lb)/42.0 mm (1.654 in)
455.0—523.7 N
(46.4—53.4 kg, 102.3—117.7 lb)/33.4 mm (1.315 in)
Cylinder
blockSurface warpage limit (mating with cylinder head) 0.05 mm (0.0020 in)
Surface grinding limit 0.1 mm (0.004 in)
Cylinder bore STDA 99.505—99.515 mm (3.9175—3.9179 in)
B 99.495—99.505 mm (3.9171—3.9175 in)
TaperSTD 0.015 mm (0.0006 in)
Limit 0.050 mm (0.0020 in)
Out-of-roundnessSTD 0.010 mm (0.0004 in)
Limit 0.050 mm (0.0020 in)
Piston clearanceSTD 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 diameterSTDA 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)
OS99.725—99.735 mm (3.9262—3.9266 in)
0.50 mm (0.0197 in)
OS99.975—99.985 mm (3.9360—3.9364 in)
Piston pinStandard clearance between piston
pin and hole in pistonSTD 0.004—0.010 mm (0.0002—0.0004 in)
Limit 0.020 mm (0.0008 in)
Degree of fitPiston pin must be fitted into position with thumb at 20°C
(68°F).
Piston ringPiston ring gapTop ringSTD 0.20—0.35 mm (0.0079—0.0138 in)
Limit 1.0 mm (0.039 in)
Second
ringSTD 0.37—0.52 mm (0.0146—0.0205 in)
Limit 1.0 mm (0.039 in)
Oil ringSTD 0.20—0.60 mm (0.0079—0.0236 in)
Limit 1.5 mm (0.059 in)
Clearance between piston
ring and piston ring grooveTop ringSTD 0.040—0.080mm (0.0016—0.0031 in)
Limit 0.15 mm (0.0059 in)
Second
ringSTD 0.030—0.070 mm (0.0012—0.0028 in)
Limit 0.15 mm (0.0059 in)
Connecting
rodBend twist per 100 mm (3.94 in) in
lengthLimit 0.10 mm (0.0039 in)
Side clearanceSTD 0.070—0.330 mm (0.0028—0.0130 in)
Limit 0.4 mm (0.016 in)
Connecting
rod bearingOil clearanceSTD 0.010—0.038 mm (0.0004—0.0015 in)
Limit 0.05 mm (0.0020 in)
Thickness at center portionSTD 1.492—1.501 mm (0.0587—0.0591 in)
0.03 mm
(0.0012 in)
US1.510—1.513 mm (0.0594—0.0596 in)
0.05 mm
(0.0020 in)
US1.520—1.523 mm (0.0598—0.0600 in)
0.25 mm
(0.0098 in)
US1.620—1.623 mm (0.0638—0.0639 in)
Connecting
rod bushingClearance between piston pin and
bushingSTD 0—0.022 mm (0—0.0009 in)
Limit 0.030 mm (0.0012 in)
STD: Standard OS: Oversize US: Undersize
4
2-3bSPECIFICATIONS AND SERVICE DATA
1. Engine

CrankshaftBend limit 0.035 mm (0.0014 in)
Crank pin and crank journalOut-of-roundness 0.020 mm (0.0008 in) or less
Grinding limit 0.25 mm (0.0098 in)
Crank pin outer diameterSTD 47.984—48.000 mm (1.8891—1.8898 in)
0.03 mm
(0.0012 in)
US47.954—47.970 mm (1.8879—1.8886 in)
0.05 mm
(0.0020 in)
US47.934—47.950 mm (1.8872—1.8878 in)
0.25 mm
(0.0098 in)
US47.734—47.750 mm (1.8793—1.8799 in)
Crank journal outer diameter#1, #5STD 59.992—60.008 mm (2.3619—2.3625 in)
0.03 mm
(0.0012 in)
US59.962—59.978 mm (2.3607—2.3613 in)
0.05 mm
(0.0020 in)
US59.942—59.958 mm (2.3599—2.3605 in)
0.25 mm
(0.0098 in)
US59.742—59.758 mm (2.3520—2.3527 in)
#2, #3, #4STD 59.992—60.008 mm (2.3619—2.3625 in)
0.03 mm
(0.0012 in)
US59.962—59.978 mm (2.3607—2.3613 in)
0.05 mm
(0.0020 in)
US59.942—59.958 mm (2.3599—2.3605 in)
0.25 mm
(0.0098 in)
US59.742—59.758 mm (2.3520—2.3527 in)
Thrust clearanceSTD 0.030—0.115 mm (0.0012—0.0045 in)
Limit 0.25 mm (0.0098 in)
Oil clearance#1, #5 STD 0.003—0.030 mm (0.0001—0.0012 in)
#2, #3, #4 STD 0.010—0.033 mm (0.0004—0.0013 in)
#1, #3, #5 Limit 0.040 mm (0.0016 in)
#2, #4 Limit 0.045 mm (0.0018 in)
Crankshaft
bearingCrankshaft bearing thickness#1, #5STD 1.998—2.011 mm (0.0787—0.0792 in)
0.03 mm
(0.0012 in)
US2.017—2.020 mm (0.0794—0.0795 in)
0.05 mm
(0.0020 in)
US2.027—2.030 mm (0.0798—0.0799 in)
0.25 mm
(0.0098 in)
US2.127—2.130 mm (0.0837—0.0839 in)
#2, #3, #4STD 2.000—2.013 mm (0.0787—0.0793 in)
0.03 mm
(0.0012 in)
US2.019—2.022 mm (0.0795—0.0796 in)
0.05 mm
(0.0020 in)
US2.029—2.032 mm (0.0799—0.0800 in)
0.25 mm
(0.0098 in)
US2.129—2.132 mm (0.0838—0.0839 in)
STD: Standard US: Undersize
5
2-3bSPECIFICATIONS AND SERVICE DATA
1. Engine