
DIAGNOSIS AND TESTINGÐCYLINDER
COMPRESSION PRESSURE
The results of a cylinder compression pressure test
can be utilized to diagnose several engine malfunc-
tions.
Ensure the battery is completely charged and the
engine starter motor is in good operating condition.
Otherwise, the indicated compression pressures may
not be valid for diagnosis purposes.
(1) Clean the spark plug recesses with compressed
air.
(2) Remove the spark plugs (Refer to 8 - ELEC-
TRICAL/IGNITION CONTROL/SPARK PLUG -
REMOVAL).
(3) Secure the throttle in the wide-open position.
(4) Disconnect the ignition coil.
(5) Insert a compression pressure gauge and rotate
the engine with the engine starter motor for three
revolutions.
(6) Record the compression pressure on the third
revolution. Continue the test for the remaining cylin-
ders.
(Refer to 9 - ENGINE - SPECIFICATIONS) for the
correct engine compression pressures.
DIAGNOSIS AND TESTINGÐCYLINDER
COMBUSTION PRESSURE LEAKAGE
The combustion pressure leakage test provides an
accurate means for determining engine condition.
Combustion pressure leakage testing will detect:
²Exhaust and intake valve leaks (improper seat-
ing)
²Leaks between adjacent cylinders or into water
jacket²Any causes for combustion/compression pressure
loss
WARNING: DO NOT REMOVE THE RADIATOR CAP
WITH THE SYSTEM HOT AND UNDER PRESSURE.
SERIOUS BURNS FROM HOT COOLANT CAN
OCCUR.
Check the coolant level and fill as required. DO
NOT install the radiator cap.
Start and operate the engine until it attains nor-
mal operating temperature, then turn OFF the
engine.
Remove the spark plugs.
Remove the oil filler cap.
Remove the air cleaner.
Calibrate the tester according to the manufactur-
er's instructions. The shop air source for testing
should maintain 483 kPa (70 psi) minimum, 1,379
kPa (200 psi) maximum and 552 kPa (80 psi) recom-
mended.
Perform the test procedure on each cylinder accord-
ing to the tester manufacturer's instructions. While
testing, listen for pressurized air escaping through
the throttle body, tailpipe or oil filler cap opening.
Check for bubbles in the radiator coolant.
All gauge pressure indications should be equal,
with no more than 25% leakage.
FOR EXAMPLE:At 552 kPa (80 psi) input pres-
sure, a minimum of 414 kPa (60 psi) should be main-
tained in the cylinder.
Refer to CYLINDER COMBUSTION PRESSURE
LEAKAGE DIAGNOSIS CHART below
CYLINDER COMBUSTION PRESSURE LEAKAGE DIAGNOSIS CHART
CONDITION POSSIBLE CAUSE CORRECTION
AIR ESCAPES THROUGH
THROTTLE BODYIntake valve bent, burnt, or not
seated properlyInspect valve and valve seat.
Reface or replace, as necessary
AIR ESCAPES THROUGH
TAILPIPEExhaust valve bent, burnt, or not
seated properlyInspect valve and valve seat.
Reface or replace, as necessary
AIR ESCAPES THROUGH
RADIATORHead gasket leaking or cracked
cylinder head or blockRemove cylinder head and inspect.
Replace defective part
MORE THAN 50% LEAKAGE
FROM ADJACENT CYLINDERSHead gasket leaking or crack in
cylinder head or block between
adjacent cylindersRemove cylinder head and inspect.
Replace gasket, head, or block as
necessary
MORE THAN 25% LEAKAGE AND
AIR ESCAPES THROUGH OIL
FILLER CAP OPENING ONLYStuck or broken piston rings;
cracked piston; worn rings and/or
cylinder wallInspect for broken rings or piston.
Measure ring gap and cylinder
diameter, taper and out-of-round.
Replace defective part as necessary
BR/BEENGINE 8.0L 9 - 179
ENGINE 8.0L (Continued)

DESCRIPTION SPECIFICATION
CYLINDER HEAD AND VALVES
Valve Seat Angle 44.5É
Runout (Max.) 0.0762 mm (0.003 in.)
Width (Finish) ± Intake 1.016 ± 1.524 mm
(0.040 ± 0.060 in.)
Valve Face Angle 45É
Valve Head Diameter
Intake 48.640 ± 48.900 mm
(1.915 ± 1.925 in.)
Exhaust 41.123 ± 41.377 mm
(1.619 ± 1.629 in.)
Overall Length
Intake 145.19 ± 145.82 mm
(5.716 ± 5.741 in.)
Exhaust 145.54 ± 146.18 mm
(5.730 ± 5.755 in.)
Lift (@ zero lash)
Intake 9.91 mm (0.390 in.)
Exhaust 10.34 mm (0.407 in.)
Stem Diameter 7.900 ± 7.920 mm
(0.311 ± 0.312 in.)
Guide Bore 9.500 ± 9.525 mm
(0.374 ± 0.375 on.)
Stem to Guide Clearance 0.025 ± 0.076 mm
(0.001 ± 0..003 in.)
Service Limit 0.4318 (0.017 in.)
Valve Spring Free Length 49.962 mm (1.967 in.)
Spring Tension
Valve Closed 378 N @ 41.66 mm
(85 lbs. @ 1.64 in.)
Valve Open 890 N @ 30.89 mm
(200 lbs. @ 1.212 in.)
Number of Coils 6.8
Installed Height 41.66 mm (1.64 in.)
Wire Diameter 4.50 mm (0.177 in.)DESCRIPTION SPECIFICATION
HYDRAULIC TAPPETS
Body Diameter 22.949 ± 22.962 mm
(0.9035 ± 0.9040 in.)
Clearance (to bore) 0.0203 ± 0.0610 mm
(0.0008 ± 0.0024 in.)
Dry Lash 1.524 ± 5.334 mm
(0.060 ± 0.210 in.)
Push Rod Length 195.52 ± 196.02 mm
(7.698 ± 7.717 in.)
OIL PRESSURE
Curb Idle (Min.*) 83 kPa (12 psi)
@ 3000 rpm 345 ± 414 kPa (50 ± 60
psi)
* If oil pressure is zero at curb idle, DO NOT RUN
ENGINE.
OIL PUMP
Clearance over Rotors
(Max.)0.1906 mm (0.0075 in.)
Cover Out of Flat (Max.) 0.051 mm (0.002 in.)
Inner Rotor Thickness
(Min.)14.925 ± 14.950 mm
(0.5876 ± 0.5886 in.)
Outer Rotor
Clearance (Max.) 0.1626 mm (0.006 in.)
Diameter (Min.) 82.461 mm (3.246 in.)
Thickness (Min.) 14.925 mm (0.5876 in.)
Tip Clearance between
Rotors
(Max.) 0.584 mm (0.0230 in.)
PISTONS
Clearance at Top of Skirt 0.013 ± 0.038 mm
(0.0005 ± 0.0015 in.)
Piston Length 82.5 mm (3.25 in.)
Piston Ring Groove
Depth
#1&2 91.30 ± 91.55 mm
(3.594 ± 3.604 in.)
#3 92.90 ± 93.15 mm
(3.657 ± 3.667 in.)
BR/BEENGINE 8.0L 9 - 185
ENGINE 8.0L (Continued)

DESCRIPTION SPECIFICATION
Weight 463 ± 473 grams (16.33
± 16.68 oz.)
Piston to Bore Clearance 0.013 ± 0.038 mm
(0.0005 ± 0.0015 in.)
Service Limit 0.0762 mm (0.003 in.)
PISTON PINS
Clearance in Piston 0.010 ± 0.020 mm
(0.0004 ± 0.0008 in.)
Diameter 24.996 ± 25.001 mm
(0.9841 ± 0.9843 in.)
End Play NONE
Length 67.8 ± 68.3 mm
(2.67 ± 2.69 in.)
PISTON RINGS
Ring Gap
Compression Rings 0.254 ± 0.508 mm
(0.010 ± 0.020 in.)
Oil Control (Steel Rails) 0.381 ± 1.397 mm
(0.015 ± 0.055 in.)
Ring Side Clearance
Compression Rings 0.074 ± 0.097 mm
(0.0029 ± 0.0038 in.)
Oil Ring (Steel Rails) 2.591 ± 2.743 mm
(0.102 ± 0.108 in.)
VALVE TIMING
Exhaust Valve
Closes (ATDC) 25É
Opens (BBDC) 60É
Duration 265É
Intake Valve
Closes (ATDC) 61É
Opens (BBDC) 6É
Duration 246É
Valve Overlap 31ÉCRANKSHAFT JOURNAL MARKING
LOCATION
MEASURE-
MENTITEM IDENTIFI-
CATIONLOCATION
OF
IDENTIFI-
CATION
0.0254 mm
(0.001 in.)
U/SCrankshaft
JournalsRorM
M-2-3 ect.
(indicating
No. 2 and
3 main
bearing
journal)
and/or
R-1-4 ect.
(indicating
No. 1 and
4
connecting
rod
journal)Milled flat
on No. 8
crankshaft
counter-
weight.
0.508 mm
(0.020 in.)
O/SCylinder
BoresA Following
engine
serial
number.
0.2032 mm
(0.008 in.)
O/SHydraulic
TappetsLDiamond-
shaped
stamp top
pad - front
of engine
and flat
ground on
outside
surface of
each O/S
tappet
bore.
0.127 mm
(0.005 in.)Valve
StemsX Milled pad
adjacent to
two tapped
holes 3/89
on each
end of
cylinder
head.
9 - 186 ENGINE 8.0LBR/BE
ENGINE 8.0L (Continued)

TORQUE
TORQUE CHART 8.0L ENGINE
DESCRIPTION N´m Ft. In.
Lbs. Lbs.
Camshaft SprocketÐBolt 75 55 Ð
Camshaft Thrust PlateÐ
Bolts22 16 Ð
Coil Pack BracketÐBolts 21 Ð 190
Connecting Rod CapÐBolts 61 45 Ð
Main BearingÐBolts
Step 1 27 20 Ð
Step 2 115 85 Ð
Crankshaft Pulley/DamperÐ
Bolt312 230 Ð
Crankshaft Rear Seal
RetainerÐ22 16 Ð
Bolts
Cylinder HeadÐBolts
Step 1 58 43 Ð
Step 2 143 105 Ð
Cylinder Head CoverÐBolts 16 Ð 144
Drive Plate to CrankshaftÐ
Bolts75 55 Ð
Drive Plate to Torque
ConverterÐ47 35 Ð
Bolts
EGR TubeÐNut 34 25 Ð
EGR ValveÐBolts 20 Ð 174
Engine Support Bracket/
InsulatorÐ68 50 Ð
Through Bolt
Engine Support Bracket/
Insulator to47 35 Ð
BlockÐBolts
Exhaust Manifold to Cylinder
HeadÐ22 16 Ð
Bolt
Generator MountingÐBolt 41 30 Ð
Generator to Intake Manifold
Bracket41 30 Ð
ÐBolts
Heat ShieldÐNuts 20 Ð 175
Hydraulic Tappet Yoke
Retaining22 16 Ð
DESCRIPTION N´m Ft. In.
Lbs. Lbs.
SpiderÐBolts
Intake Manifold (Lower)Ð
Bolts54 40 Ð
Intake Manifold (Upper)Ð
Bolts22 16 Ð
Oil Filter 9 Ð 80 +
45É
Oil Filter Connector 46 34 Ð
Oil Pan
Ð1/4 - 20 Bolts 11 Ð 96
Ð5/16 - 18 Bolts 16 Ð 144
ÐStud Bolts 16 Ð 144
ÐDrain Plug 34 25 Ð
Oil Pan Pick Up TubeÐBolts 16 Ð 144
Oil Pump AttachingÐBolts 41 30 Ð
Oil Pump CoverÐBolts 14 Ð 125
Oil Pump Pressure
ReliefÐPlug20 15 Ð
Rocker ArmÐBolts 28 21 Ð
Spark Plugs 41 30 Ð
Starter MountingÐBolts 68 50 Ð
Timing Chain CoverÐBolts 47 35 Ð
Thermostat HousingÐBolts 25 Ð 220
Throttle BodyÐNuts 11 Ð 96
Transfer Case to Insulator
Mounting204 150 Ð
PlateÐNuts
Transmission Support
BracketÐ102 75 Ð
Bolts
Transmission Support
CushionÐ47 35 Ð
Bolts
Transmission Support
Cushion47 35 Ð
StudÐNuts
Water Pump to Chain Case
CoverÐ41 30 Ð
Bolts
BR/BEENGINE 8.0L 9 - 187
ENGINE 8.0L (Continued)

SPECIAL TOOLS
8.0L ENGINE
Valve Compressor Adapting Stud Tool 6715
Valve Spring Compressor Adapter Tool 6716A
Valve Spring Compressor Tool MD-998772A
Valve Spring Compressor Screw Tool 6756
Black Valve Guide Sleeve Tool C6819
Silver Valve Guide Sleeve Tool C6818
Dial Indicator Tool C3339
Crankshaft Pulley/Damper Installer Tool C3688
Crankshaft Sprocket Puller Tool 6444
Crankshaft Sprocket Puller Jaws Tool 6820
9 - 188 ENGINE 8.0LBR/BE
ENGINE 8.0L (Continued)

(1) After installing housing, tighten 4 nuts to 11
N´m (96 in. lbs.) torque and connect crankcase vent
hose.
(2) Position air cleaner element (filter) into air
cleaner cover. Latch spring clips to seal cover to
housing.
(3) Install air inlet tube at air cleaner housing
inlet.
(4) Install and tighten clamp at air inlet tube (Fig.
6).
CYLINDER HEAD
DESCRIPTION
The alloy cast iron cylinder heads (Fig. 7) are held
in place by 12 bolts. The spark plugs are located in
the peak of the wedge between the valves.
DIAGNOSIS AND TESTINGÐCYLINDER HEAD
GASKET FAILURE
A cylinder head gasket leak can be located between
adjacent cylinders or between a cylinder and the
adjacent water jacket.
²Possible indications of the cylinder head gasket
leaking between adjacent cylinders are:
²Loss of engine power
²Engine misfiring
²Poor fuel economy
²Possible indications of the cylinder head gasket
leaking between a cylinder and an adjacent water
jacket are:
²Engine overheating
²Loss of coolant²Excessive steam (white smoke) emitting from
exhaust
²Coolant foaming
CYLINDER-TO-CYLINDER LEAKAGE TEST
To determine if an engine cylinder head gasket is
leaking between adjacent cylinders, follow the proce-
dures in Cylinder Compression Pressure Test in this
section. An engine cylinder head gasket leaking
between adjacent cylinders will result in approxi-
mately a 50±70% reduction in compression pressure.
CYLINDER-TO-WATER JACKET LEAKAGE TEST
WARNING: USE EXTREME CAUTION WHEN THE
ENGINE IS OPERATING WITH COOLANT PRES-
SURE CAP REMOVED.
VISUAL TEST METHOD
With the engine cool, remove the coolant pressure
cap. Start the engine and allow it to warm up until
thermostat opens.
If a large combustion/compression pressure leak
exists, bubbles will be visible in the coolant.
Fig. 6 Clamp InstallationÐ8.0L Engine
1 - CLAMP
2 - ADJUSTABLE PLIERS
Fig. 7 Cylinder Head Assembly
1 - SPARK PLUG
2 - INTAKE VALVES
3 - SPARK PLUG
4 - INTAKE VALVES
5 - SPARK PLUG
6 - SPARK PLUG
7 - INTAKE VALVE
8 - SPARK PLUG
9 - EXHAUST VALVE
10 - EXHAUST VALVES
11 - EXHAUST VALVES
BR/BEENGINE 8.0L 9 - 191
AIR CLEANER ELEMENT (Continued)

ARM / ADJUSTER ASSY - REMOVAL). Identify to
ensure installation in original locations.
(21) Remove the head bolts from each cylinder
head and remove cylinder heads. Discard the cylin-
der head gasket.
(22) Remove spark plugs.
CLEANING
Clean all surfaces of cylinder block and cylinder
heads. Be sure material does not fall into the lifters
and surrounding valley.
Clean cylinder block front and rear gasket surfaces
using a suitable solvent.
Clean the exhaust manifold to cylinder head mat-
ing areas.
INSPECTION
Inspect all surfaces with a straightedge if there is
any reason to suspect leakage. The out-of-flatness
specifications are 0.0007 mm/mm (0.0004 inch/inch),
0.127 mm/152 mm (0.005 inch/6 inches) any direction
or 0.254 mm (0.010 inch) overall across head. If
exceeded, either replace head or lightly machine the
head surface.
The cylinder head surface finish should be
1.78-4.57 microns (15-80 microinches).
Inspect push rods. Replace worn or bent rods.
Inspect rocker arms. Replace if worn or scored.
INSTALLATION
(1) Position the new cylinder head gaskets onto
the cylinder block.
(2) Position the cylinder heads onto head gaskets
and cylinder block.
(3) Tighten the cylinder head bolts in two steps
(Fig. 10):
²Step 1ÐTighten all cylinder head bolts, in
sequence, to 58 N´m (43 ft. lbs.) torque.
²Step 2ÐTighten all cylinder head bolts, in
sequence, to 143 N´m (105 ft. lbs.) torque.
²
CAUTION: When tightening the rocker arm bolts,
make sure the piston in that cylinder is NOT at
TDC. Contact between the valves and piston could
occur.
(4) Install push rods and rocker arm assemblies in
their original position (Refer to 9 - ENGINE/CYLIN-
DER HEAD/ROCKER ARM / ADJUSTER ASSY -
INSTALLATION).
(5) Install lower intake manifold (Refer to 9 -
ENGINE/MANIFOLDS/INTAKE MANIFOLD -
INSTALLATION).(6) Install the upper intake manifold onto the
lower intake manifold (Refer to 9 - ENGINE/MANI-
FOLDS/INTAKE MANIFOLD - INSTALLATION).
(7) Install the exhaust manifolds and new gaskets
(Refer to 9 - ENGINE/MANIFOLDS/EXHAUST
MANIFOLD - INSTALLATION).
(8) Install exhaust pipe to the exhaust manifold.
Tighten the bolts to 34 n´m (25 ft. lbs.) torque.
(9) Using a new gasket, position the EGR tube to
the intake manifold and the exhaust manifold.
Tighten the EGR tube nut to 34 N´m (25 ft. lbs.)
torque. Tighten the bolts to 20 N´m (174 in. lbs.)
torque.
(10) Install the heat shields and the washers.
Make sure that heat shields tabs hook over the
exhaust gasket.Tighten the nuts to 15 N´m (132 in.
lbs.) torque.
(11) Adjust and Install the spark plugs (Refer to 8
- ELECTRICAL/IGNITION CONTROL/SPARK
PLUG - INSTALLATION).
(12) Install coil packs and bracket. Tighten the
bracket bolts to 21 N´m (190 in. lbs.) torque. Connect
the coil wires.
(13) Connect heat indicator sending unit wire.
(14) Connect the heater hoses and bypass hose.
(15) Connect the accelerator linkage and if so
equipped, the speed control and transmission kick-
down cables.
(16) Install the fuel line (Refer to 14 - FUEL SYS-
TEM/FUEL DELIVERY/QUICK CONNECT FIT-
TING - STANDARD PROCEDURE).
(17) Install the generator (Refer to 8 - ELECTRI-
CAL/CHARGING/GENERATOR - INSTALLATION)
and drive belt (Refer to 7 - COOLING/ACCESSORY
DRIVE/DRIVE BELTS - INSTALLATION).
(18) Install the intake manifold-to-generator
bracket support rod. Tighten the bolts to 41 N´m (30
ft. lbs.) torque.
(19) The cylinder head cover gasket can be used
again. Install the gasket onto the head rail.For the
left side the number tab is at the front of
engine with the number up. For the right side
the number tab is at the rear of engine with the
number up.
Fig. 10 Cylinder Head Bolt Tightening Sequence
BR/BEENGINE 8.0L 9 - 193
CYLINDER HEAD (Continued)

(5) Install closed crankcase ventilation system and
evaporation control system onto the proper head
cover. DO NOT switch the systems.
(6) Connect the negative cable to the battery.
(7) Start engine and check for leaks.
INTAKE/EXHAUST VALVES &
SEATS
DESCRIPTION
The valves (Fig 14) are arranged in-line and
inclined 18É. The rocker pivot support and the valve
guides are cast integral with the heads.
VALVE SERVICE
VALVE GUIDES
Measure valve stem guide clearance as follows:
(1) Install Black Valve Guide Sleeve Tool C-6819
over valve stem for theINTAKEvalve and install
valve (Fig. 15). The special sleeve places the valve at
the correct height for checking with a dial indicator.(2) Install Silver Valve Guide Sleeve Tool C-6818
over valve stem for theEXHAUSTvalve and install
valve. The special sleeve places the valve at the cor-
rect height for checking with a dial indicator.
(3) Attach Dial Indicator Tool C-3339 to cylinder
head and set it at right angle of valve stem being
measured (Fig. 16).
(4) Move valve to and from the indicator. The total
dial indicator reading should not exceed 0.432 mm
(0.017 inch). Ream the guides for valves with over-
size stems if dial indicator reading is excessive or if
the stems are scuffed or scored.
Service valves with oversize stems are available as
shown below
Fig. 13 Cylinder Head Covers
1 - CYLINDER HEAD COVER
2 - CYLINDER HEAD COVER GASKET
Fig. 14 Intake and Exhaust ValvesÐ8.0L Engine
1 - MARGIN
2 - VALVE SPRING RETAINER LOCK GROOVE
3 - STEM
4-FACE
Fig. 15 Positioning Valve Spacer Tool (Typical)
1 - VALVE
2 - SPACER TOOL
BR/BEENGINE 8.0L 9 - 195
CYLINDER HEAD COVER(S) (Continued)