DIAGNOSIS AND TESTING-ENGINE DIAGNOSIS
- INTRODUCTION
Engine diagnosis is helpful in determining the
causes of malfunctions not detected and remedied by
routine maintenance.
These malfunctions may be classified as either
mechanical (e.g., a strange noise), or performance
(e.g., engine idles rough and stalls).
(Refer to 9 - ENGINE - DIAGNOSIS AND TEST-
ING - Preformance) or (Refer to 9 - ENGINE - DIAG-
NOSIS AND TESTING - Mechanical). Refer to 14 -
FUEL SYSTEM for fuel system diagnosis.Additional tests and diagnostic procedures may be
necessary for specific engine malfunctions that can-
not be isolated with the Service Diagnosis charts.
Information concerning additional tests and diagno-
sis is provided within the following:
²Cylinder Compression Pressure Test
²Cylinder Combustion Pressure Leakage Test
²Cylinder Head Gasket Failure Diagnosis
²Intake Manifold Leakage Diagnosis
²Lash Adjuster (Tappet) Noise Diagnosis
²Engine Oil Leak Inspection
DIAGNOSIS AND TESTINGÐPERFORMANCE
PERFORMANCE DIAGNOSIS CHARTÐGASOLINE ENGINES
CONDITION POSSIBLE CAUSES CORRECTION
ENGINE WILL NOT CRANK 1. Weak or dead battery 1. Charge/Replace Battery. (Refer to 8
- ELECTRICAL/BATTERY SYSTEM/
BATTERY - STANDARD
PROCEDURE). Check charging
system. (Refer to 8 - ELECTRICAL/
CHARGING - DIAGNOSIS AND
TESTING).
2. Corroded or loose battery
connections2. Clean/tighten suspect battery/starter
connections
3. Faulty starter or related circuit(s) 3. Check starting system. (Refer to 8 -
ELECTRICAL/STARTING -
DIAGNOSIS AND TESTING)
4. Seized accessory drive component 4. Remove accessory drive belt and
attempt to start engine. If engine starts,
repair/replace seized component.
5. Engine internal mechanical failure or
hydro-static lock5. Refer to (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)
ENGINE CRANKS BUT WILL
NOT START1. No spark 1. Check for spark. (Refer to 8 -
ELECTRICAL/IGNITION CONTROL -
DESCRIPTION)
2. No fuel 2. Perform fuel pressure test, and if
necessary, inspect fuel injector(s) and
driver circuits. (Refer to 14 - FUEL
SYSTEM/FUEL DELIVERY/FUEL
PUMP - DIAGNOSIS AND TESTING).
3. Low or no engine compression 3. Perform cylinder compression
pressure test. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING).
ENGINE LOSS OF POWER 1. Worn or burned distributor rotor 1. Install new distributor rotor
2. Worn distributor shaft 2. Remove and repair distributor (Refer
to 8 - ELECTRICAL/IGNITION
CONTROL/DISTRIBUTOR -
REMOVAL).
BR/BEENGINE 5.2L 9 - 61
ENGINE 5.2L (Continued)
SPECIFICATIONS
5.2L ENGINE
ENGINE SPECIFICATIONS
DESCRIPTION SPECIFICATION
GENERAL SPECIFICATIONS
Engine Type 90É V-8 OHV
Bore and Stroke 99.3 x 84.0 mm
(3.91 x 3.31 in.)
Displacement 5.2L
(318 c.i.)
Compression Ratio 9.1:1
Firing Order 1±8±4±3±6±5±7±2
Lubrication Pressure FeedÐ
Full Flow Filtration
Cooling System Liquid CooledÐ
Forced Circulation
Cylinder Block Cast Iron
Crankshaft Nodular Iron
Cylinder Head Cast Iron
Combustion Chambers Wedge-High Swirl
Valve shrouding
Camshaft Nodular Cast Iron
Pistons Aluminum Alloy w/strut
Connecting Rods Forged Steel
Cylinder Compression 689.5 kPa
Pressure (Min.) (100 psi)
CAMSHAFT
Bearing Diameter
No. 1 50.800 ± 50.825 mm
(2.000 ± 2.001 in.)
No. 2 50.394 ± 50.419 mm
(1.984 ± 1.985 in.)
No. 3 50.013 ± 50.038 mm
(1.969 ± 1.970 in.)
No. 4 49.606 ± 49.632 mm
(1.953 ± 1.954 in.)
DESCRIPTION SPECIFICATION
No. 5 39.688 ± 39.713 mm
(1.5625 ± 1.5635 in.)
Bearing Journal Diameter
No. 1 50.749 ± 50.775 mm
(1.998 ± 1.999 in.)
No. 2 50.343 ± 50.368 mm
(1.982 ± 1.983 in.)
No. 3 49.962 ± 49.987 mm
(1.967 ± 1.968 in.)
No. 4 49.555 ± 49.581 mm
(1.951 ± 1.952 in.)
No. 5 39.637 ± 39.662 mm
(1.5605 ± 1.5615 in.)
Bearing to Journal
Clearance
Standard 0.0254 ± 0.0762 mm
(0.001 ± 0.003 in.)
Service Limit 0.127 mm
(0.005 in.)
End Play 0.051 ± 0.254 mm
(0.002 ± 0.010 in.)
CONNECTING RODS
Piston Pin bore Diameter 24.966 ± 24.978 mm
(0.9829 ± 0.9834 in.)
Side Clearance 0.152 ± 0.356 mm
(0.006 ± 0.014 in.)
CRANKSHAFT
Rod Journal
Diameter 53.950 ± 53.975 mm
(2.124 ± 2.125 in.)
Out of Round (Max.) 0.0254 mm
(0.001 in.)
Taper (Max.) 0.0254 mm
(0.001 in.)
Bearing Clearance 0.013 ± 0.056 mm
(0.0005 ± 0.0022 in.)
Service Limit 0.0762 mm
(0.003 in.)
9 - 72 ENGINE 5.2LBR/BE
ENGINE 5.2L (Continued)
DESCRIPTION SPECIFICATION
Main Bearing Journal
Diameter 63.487 ± 63.513 mm
(2.4995 ± 2.5005in.)
Out of Round (Max.) 0.127 mm
(0.001 in.)
Taper (Max.) 0.0254 mm
(0.001 in.)
Bearing Clearance
(#1 Journal) 0.013 ± 0.038 mm
(0.0005 ± 0.0015 in.)
(#2-5 Journals) 0.013 ± 0.051 mm
(0.0005 ± 0.002 in.)
Service Limit
(#1 Journal) 0.0381 mm
(0.0015 in.)
(#2-5 Journals) 0.064 mm
(0.0025 in.)
End Play 0.051 ± 0.178 mm
(0.002 ± 0.007 in.)
Service Limit 0.254 mm
(0.010 in.)
CYLINDER BLOCK
Cylinder Bore
Diameter 99.308 ± 99.371 mm
(3.9098 ± 3.9122 in.)
Out of Round (Max.) 0.025 mm
(0.001 in.)
Taper (Max.) 0.025 mm
(0.001 in.)
Oversize Limit 1.016 mm
(0.040 in.)
Lifter Bore Diameter 22.99 ± 23.01 mm
(0.9051 ± 0.9059 in.)
Distributor Drive Bushing
(Press Fit)
Bushing to Bore
Interference0.0127 ± 0.3556 mm
(0.0005 ± 0.0140 in.)
Shaft to Bushing
Clearance0.0178 ± 0.0686 mm
(0.0007 ± 0.0027 in.)DESCRIPTION SPECIFICATION
CYLINDER HEAD
Valve Seat
Angle 44.25É ± 44.75É
Runout (Max.) 0.0762 mm
(0.003 in.)
Width (Finish)
Intake 1.016 ± 1.524 mm
(0.040 ± 0.060 in.)
Exhaust 1.524 ± 2.032 mm
(0.060 ± 0.080 in.)
VA LV E S
Face Angle 43.25É ± 43.75É
Head Diameter
Intake 48.666 mm
(1.916 in.)
Exhaust 41.250 mm
(1.624 in.)
Length (Overall)
Intake 124.28 ± 125.92 mm
(4.893 ± 4.918 in.)
Exhaust 124.64 ± 125.27 mm
(4.907 ± 4.932 in.)
Lift (@ zero lash) 10.973 mm
(0.432 in.)
Stem Diameter 7.899 ± 7.925 mm
(0.311 ± 0.312 in.)
Guide Bore 7.950 ± 7.976 mm
(0.313 ± 0.314 on.)
Stem to Guide Clearance 0.0254 ± 0.0762 mm
(0.001 ± 0.003 in.)
Service Limit (rocking
method)0.4318 mm
(0.017 in.)
VALVE SPRINGS
Free Length 49.962 mm
(1.967 in.)
Spring Tension
BR/BEENGINE 5.2L 9 - 73
ENGINE 5.2L (Continued)
STANDARD PROCEDUREÐVALVES, GUIDES
AND SPRINGS
VALVE CLEANING
Clean valves thoroughly. Discard burned, warped,
or cracked valves.
Remove carbon and varnish deposits from inside of
valve guides with a reliable guide cleaner.
VALVE GUIDES
Measure valve stems for wear. If wear exceeds
0.051 mm (0.002 in.), replace the valve.
Measure valve stem guide clearance as follows:
(1) Install Valve Guide Sleeve Tool C-3973 over
valve stem and install valve (Fig. 8). The special
sleeve places the valve at the correct height for
checking with a dial indicator.
(2) Attach dial indicator Tool C-3339 to cylinder
head and set it at right angles to valve stem being
measured (Fig. 9).
(3) Move valve to and from the indicator. The total
dial indicator reading should not exceed 0.432 mm
(0.017 in.). Ream the guides for valves with oversize
stems if dial indicator reading is excessive or if the
stems are scuffed or scored.
VALVE GUIDES
Service valves with oversize stems are available.
Refer to REAMER SIZES CHART
REAMER SIZES CHART
REAMER O/S VALVE GUIDE SIZE
0.076 mm 8.026 - 8.052 mm
(0.003 in.) (0.316 - 0.317 in.)
0.381 mm 8.331 - 8.357 mm
(0.015 in.) (0.328 - 0.329 in.)
(1) Slowly turn reamer by hand and clean guide
thoroughly before installing new valve.Ream the
valve guides from standard to 0.381 mm (0.015
in.). Use a two step procedure so the valve
guides are reamed true in relation to the valve
seat:
²Step 1ÐReam to 0.0763 mm (0.003 inch).
²Step 2ÐReam to 0.381 mm (0.015 inch).
Fig. 8 Positioning Valve with Tool C-3973
1 - VALVE
2 - SPACER TOOL
Fig. 9 Measuring Valve Guide Wear
1 - VALVE
2 - SPECIAL TOOL C-3339
9 - 82 ENGINE 5.2LBR/BE
INTAKE/EXHAUST VALVES & SEATS (Continued)
ENGINE BLOCK
CLEANING
Clean cylinder block thoroughly and check all core
hole plugs for evidence of leakage.
INSPECTION
Examine block for cracks or fractures.
The cylinder walls should be checked for out-of-
round and taper. Refer to Honing Cylinder Bores in
the Service Procedures portion of this Section.
Inspect the oil line plug, the oil line plug is located
in the vertical passage at the rear of the block
between the oil-to-filter and oil-from-filter passages
(Fig. 17). Improper installation or missing plug could
cause erratic, low, or no oil pressure.
The oil plug must come out the bottom. Use flat
dowel, down the oil pressure sending unit hole from
the top, to remove oil plug.
(1)
Remove oil pressure sending unit from back of block.
(2) Insert a 3.175 mm (1/8 in.) finish wire, or
equivalent, into passage.
(3) Plug should be 190.0 to 195.2 mm (7-1/2 to
7-11/16 in.) from machined surface of block (Fig. 17).
If plug is too high, use a suitable flat dowel to posi-
tion properly.(4)
If plug is too low, remove oil pan and No. 4 main
bearing cap. Use suitable flat dowel to position properly.
Coat outside diameter of plug with MopartStud and
Bearing Mount Adhesive. Plug should be 54.0 to 57.7
mm (2-1/8 to 2-5/16 in.) from bottom of the block.
CAMSHAFT & BEARINGS (IN
BLOCK)
REMOVALÐCAMSHAFT BEARINGS
NOTE: This procedure requires that the engine is
removed from the vehicle.
(1) With engine completely disassembled, drive out
rear cam bearing core plug.
(2) Install proper size adapters and horseshoe
washers (part of Camshaft Bearing Remover/Installer
Tool C-3132-A) at back of each bearing shell. Drive
out bearing shells (Fig. 18).
REMOVALÐCAMSHAFT
NOTE: The camshaft has an integral oil pump and
distributor drive gear (Fig. 19).
Fig. 17 Oil Line Plug
1 - RIGHT OIL GALLERY
2 - CYLINDER BLOCK
3 - OIL FROM FILTER TO SYSTEM
4 - OIL TO FILTER
5 - FROM OIL PUMP
6 - CRANKSHAFT
7 - PLUG
Fig. 18 Camshaft Bearings
1 - SPECIAL TOOL C-3132±A
2 - MAIN BEARING OIL HOLE
Fig. 19 Camshaft and Sprocket Assembly
1 - THRUST PLATE
2 - OIL PUMP AND DISTRIBUTOR DRIVE GEAR INTEGRAL
WITH CAMSHAFT
3 - CAMSHAFT SPROCKET
9 - 86 ENGINE 5.2LBR/BE
CRANKSHAFT MAIN
BEARINGS
DESCRIPTION
Main bearings (Fig. 25) are located in the cylinder
block. One half of the main bearing is located in the
crankshaft main bore the other half of the matching
bearing is located in the main bearing cap. there are
five main bearings. Number three main bearing is
flanged, this flange controls crankshaft thrust.
OPERATION
The main bearings encircle the crankshaft main
bearing journals, this aligns the crankshaft to the
centerline of the engine and allows the crankshaft to
turn without wobbling or shaking therefore eliminat-
ing vibration. The main bearings are available in
standard and undersizes.
STANDARD PROCEDUREÐCRANKSHAFT MAIN
BEARING FITTING
Bearing caps are not interchangeable and should
be marked at removal to ensure correct assembly.
Upper and lower bearing halves are NOT inter-
changeable. Lower main bearing halves of No.2 and 4
are interchangeable.
Upper and lower No.3 bearing halves are flanged
to carry the crankshaft thrust loads. They are NOT
interchangeable with any other bearing halves in the
engine (Fig. 26). Bearing shells are available in stan-
dard and the following undersizes: Never install an
undersize bearing that will reduce clearance below
specifications.
Main Bearing Undersize Availability List
²0.25 mm (0.001 inch)
²0.051 mm (0.002 inch)
²0.076 mm (0.003 inch)
²0.254 mm (0.010 inch)
²0.305 mm (0.012 inch)
REMOVAL
(1) Remove the oil pan (Refer to 9 - ENGINE/LU-
BRICATION/OIL PAN - REMOVAL).
(2) Remove the oil pump from the rear main bear-
ing cap (Refer to 9 - ENGINE/LUBRICATION/OIL
PUMP - REMOVAL).
(3) Identify bearing caps before removal. Remove
bearing caps one at a time.
(4) Remove upper half of bearing by inserting
Crankshaft Main Bearing Remover/Installer Tool
C-3059 into the oil hole of crankshaft (Fig. 27).
(5) Slowly rotate crankshaft clockwise, forcing out
upper half of bearing shell.
INSTALLATION
Only one main bearing should be selectively fitted
while all other main bearing caps are properly tight-
ened. All bearing capbolts removed during service
procedures are to be cleaned and oiled before instal-
lation.
When installing a new upper bearing shell, slightly
chamfer the sharp edges from the plain side.
(1) Start bearing in place, and insert Crankshaft
Main Bearing Remover/Installer Tool C-3059 into oil
hole of crankshaft (Fig. 27).
(2) Slowly rotate crankshaft counterclockwise slid-
ing the bearing into position. Remove Tool C-3059.
(3) Install the bearing caps. Clean and oil the
bolts. Tighten the capbolts to 115 N´m (85 ft. lbs.)
torque.
(4) Install the oil pump (Refer to 9 - ENGINE/LU-
BRICATION/OIL PUMP - INSTALLATION).
Fig. 25 Main Bearing Orientation
Fig. 26 Main Bearing
9 - 90 ENGINE 5.2LBR/BE
OPERATION
The crankshaft seals prevent oil from leaking from
around the crankshaft, either from the rear of the
engine or from the engine front cover.
REMOVAL
The service seal is a two piece, Viton seal. The
upper seal half can be installed with crankshaft
removed from engine or with crankshaft installed.
When a new upper seal is installed, install a new
lower seal. The lower seal half can be installed only
with the rear main bearing cap removed.
UPPER SEAL ÐCRANKSHAFT REMOVED
(1) Remove the crankshaft (Refer to 9 - ENGINE/
ENGINE BLOCK/CRANKSHAFT - REMOVAL). Dis-
card the old upper seal.
UPPER SEALÐCRANKSHAFT INSTALLED
(1) Remove the oil pan (Refer to 9 - ENGINE/LU-
BRICATION/OIL PAN - REMOVAL).
(2) Remove the oil pump (Refer to 9 - ENGINE/
LUBRICATION/OIL PUMP - REMOVAL).
(3) Remove the rear main bearing cap. Remove
and discard the old lower oil seal.
(4) Carefully remove and discard the old upper oil
seal.
LOWER SEAL
(1) Remove the oil pan (Refer to 9 - ENGINE/LU-
BRICATION/OIL PAN - REMOVAL).
(2) Remove the oil pump (Refer to 9 - ENGINE/
LUBRICATION/OIL PUMP - REMOVAL).
(3) Remove the rear main bearing cap and discard
the old lower seal.
INSTALLATION
The service seal is a two piece, Viton seal. The
upper seal half can be installed with crankshaft
removed from engine or with crankshaft installed.
When a new upper seal is installed, install a new
lower seal. The lower seal half can be installed only
with the rear main bearing cap removed.
UPPER SEAL ÐCRANKSHAFT REMOVED
(1) Clean the cylinder block rear cap mating sur-
face. Be sure the seal groove is free of debris. Check
for burrs at the oil hole on the cylinder block mating
surface to rear cap.
(2) Lightly oil the new upper seal lips with engine
oil.
(3) Install the new upper rear bearing oil seal with
the white paint facing toward the rear of the engine.
(4) Position the crankshaft into the cylinder block.
(5) Lightly oil the new lower seal lips with engine
oil.
Fig. 29 Position Tool and Seal onto Crankshaft
1 - SPECIAL TOOL 6635
2 - OIL SEAL
3 - TIMING CHAIN COVER
Fig. 30 Installing Oil Seal
1 - SPECIAL TOOL 6635
2 - TIMING CHAIN COVER
9 - 92 ENGINE 5.2LBR/BE
CRANKSHAFT OIL SEAL - REAR (Continued)
DIAGNOSIS AND TESTINGÐENGINE OIL
LEAKS
Begin with a through visual inspection of the
engine, particularly at the area of the suspected leak.
If an oil leak source is not readily identifiable, the
following steps should be followed:
(1) Do not clean or degrease the engine at this
time because some solvents may cause rubber to
swell, temporarily stopping the leak.
(2) Add an oil-soluble dye (use as recommended by
manufacturer). Start the engine and let idle for
approximately 15 minutes. Check the oil dipstick to
be sure the dye is thoroughly mixed as indicated
with a bright yellow color under a black light source.
(3) Using a black light, inspect the entire engine
for fluorescent dye, particularly at the suspected area
of oil leak. If the oil leak is found and identified,
repair per service manual instructions.
(4) If dye is not observed, drive the vehicle at var-
ious speeds for approximately 24km (15 miles), and
repeat previous step.
(5) If the oil leak source is not positively identified
at this time, proceed with the air leak detection test
method as follows:
(6) Disconnect the breather cap to air cleaner hose
at the breather cap end. Cap or plug breather cap
nipple.
(7) Remove the PCV valve from the cylinder head
cover. Cap or plug the PCV valve grommet.
(8) Attach an air hose with pressure gauge and
regulator to the dipstick tube.
CAUTION: Do not subject the engine assembly to
more than 20.6 kpa (3 PSI) of test pressure.
(9) Gradually apply air pressure from 1 psi to 2.5
psi maximum while applying soapy water at the sus-
pected source. Adjust the regulator to the suitable
test pressure that provide the best bubbles which
will pinpoint the leak source. If the oil leak is
detected and identified, repair per service manual
procedures.
(10) If the leakage occurs at the rear oil seal area,
refer to the section, Inspection for Rear Seal Area
Leak.
(11) If no leaks are detected, turn off the air sup-
ply and remove the air hose and all plugs and caps.
Install the PCV valve and breather cap hose. Proceed
to next step.
(12) Clean the oil off the suspect oil leak area
using a suitable solvent. Drive the vehicle at various
speeds approximately 24 km (15 miles). Inspect the
engine for signs of an oil leak by using a black light.
DIAGNOSIS AND TESTINGÐENGINE OIL
PRESSURE
(1) Remove oil pressure sending unit.
(2) Install Oil Pressure Line and Gauge Tool
C-3292. Start engine and record pressure. (Refer to 9
- ENGINE - SPECIFICATIONS).
OIL
STANDARD PROCEDUREÐENGINE OIL
OIL LEVEL INDICATOR (DIPSTICK)
The engine oil level indicator is located at the right
front of the engine, left of the generator on 3.9L
engines (Fig. 50).
CRANKCASE OIL LEVEL INSPECTION
CAUTION: Do not overfill crankcase with engine oil,
oil foaming and oil pressure loss can result.
To ensure proper lubrication of an engine, the
engine oil must be maintained at an acceptable level.
The acceptable levels are indicated between the ADD
and SAFE marks on the engine oil dipstick.
(1) Position vehicle on level surface.
(2) With engine OFF, allow approximately ten min-
utes for oil to settle to bottom of crankcase, remove
engine oil dipstick.
(3) Wipe dipstick clean.
(4) Install dipstick and verify it is seated in the
tube.
Fig. 50 Oil Level Indicator Location
1 - CYLINDER HEAD COVER
2 - ENGINE OIL FILL CAP
3 - DIPSTICK
4 - ENGINE OIL FILTER
5 - FILTER BOSS
9 - 104 ENGINE 5.2LBR/BE
LUBRICATION (Continued)