4.0L 6-CYL - VIN [S]
1993 Jeep Cherokee
1993 CHRYSLER CORP. ENGINES 4.0L 6-Cylinder
Jeep: Cherokee, Grand Cherokee, Wrangler
ENGINE IDENTIFICATION
NOTE: For engine repair procedures not covered in this article,
see ENGINE OVERHAUL PROCEDURES - GENERAL INFORMATION article in the GENERAL INFORMATION section.
The Vehicle Identification Number (VIN) is located on the upper left side of the dash and is visible through the windshield. The eighth character identifies engine size.
ENGINE IDENTIFICATION CODES TABLE
Application
VIN Code
4 . 0L
6-Cylinder PFI S
Some engines are manufactured with oversize or undersize components. These engines are identified by a letter code stamped on a boss between ignition coil and distributor. Letters are decoded as follows:
"B" indicates all cylinder bores are .010" (.25 mm) oversize.
"C"
indicates all camshaft bearing bores are .010" (.25
mm)
oversize.
"M"
indicates all main bearing journals are .010" (.25
mm)
undersize.
"P"
indicates one or more connecting rod journals are .010"
(.25
mm) undersize.
"PM"
indicates all main journals and one or more rod
journal
are .010" (.25 mm)
undersize.
ADJUSTMENTS
VALVE CLEARANCE ADJUSTMENT
Engine is equipped with hydraulic valve lifters. Valve adjustment is not required.
REMOVAL & INSTALLATION
* PLEASE READ THIS FIRST *
CAUTION: When battery is disconnected, vehicle computer and memory systems may lose memory data. Driveability problems may exist until computer systems have completed a relearn cycle. See COMPUTER RELEARN PROCEDURES article in the GENERAL INFORMATION section before disconnecting battery.
NOTE: For reassembly reference, label all electrical connectors, vacuum hoses and fuel lines before removal. Also place mating marks on engine hood and other major assemblies before removal.
FUEL PRESSURE RELEASE
CAUTION: Fuel system is under constant pressure. This pressure must be released before disconnecting or servicing any fuel supply or return system component. Wear proper eye protection when releasing fuel system pressure.
Disconnect negative battery cable. Remove fuel filler cap. Remove cap from pressure test port on fuel rail. See Fig. 1. Place shop towels around pressure test port to absorb spilled fuel. Press test port valve with a small screwdriver or punch wrapped in shop towels. Remove shop towels and dispose of properly. Install pressure test port cap.
Test
Port
Fig. 1: Locating Fuel Pressure Bleeding Test Port Courtesy of Chrysler Corp.
CAUTION: Always replace "O" rings, spacers and retainers whenever
fuel system quick-connect fittings are disconnected. Ensure fuel connections are secure by verifying that only retaining tabs protrude from connectors and by pulling on tubes to verify they are locked into place.
COOLING SYSTEM BLEEDING
CAUTION: Engine coolant may be hot. To avoid scalding, carefully
release system pressure before removing radiator cap or opening drain cock.
Add coolant only when engine is cold. Fill radiator completely and install pressure cap. Fill reserve/overflow tank to FULL mark. Operate engine until it reaches normal operating temperature. Shut off engine and allow it to cool. Recheck coolant level in reserve/overflow tank as necessary.
ENGINE
Removal (Except Wrangler)
Remove
hood. Disconnect battery cables. Remove battery.
Remove air
cleaner. Unplug quick-connect vacuum hose fittings at
intake
manifold. Drain cooling system. Remove radiator hoses and
radiator
support. Disconnect harness from electric fan motor (if
equipped).
Remove fan shroud and fan. Disconnect transmission cooler
lines
(if equipped). Remove radiator.
Discharge A/C system (if equipped) using approved
refrigerant recovery/recycling equipment. Remove A/C service valves. Cap compressor ports. Remove A/C condenser. Disconnect heater hoses at water pump and thermostat housing. Disconnect cruise control (if equipped) and throttle linkage. Disconnect distributor wiring, oil pressure sender wire and fuel injection wire harness at each injector. Tag connectors for installation reference.
Disconnect
line pressure cable to A/T (if equipped).
Release
fuel pressure. See FUEL PRESSURE RELEASE. Disconnect fuel
supply
quick-connect fittings at fuel rail. Remove fuel line bracket
from
intake manifold. Remove check valve from power brake booster
(if
equipped). Disconnect
power steering hoses at steering gear (if
equipped). Drain
power steering pump reservoir. Cap power steering
hoses
and fittings.
Tag
and disconnect any remaining vacuum hoses and
electrical
connectors as required. Raise and support vehicle.
Disconnect
exhaust pipe from exhaust manifold. Remove starter and
flywheel
cover. Disconnect oxygen (O2) sensor.
Disconnect engine speed
sensor.
On A/T models, mark converter and flexplate for
installation reference. Remove converter-to-flexplate bolts. Remove upper and loosen lower bellhousing bolts. Remove engine mount bracket bolts. Lower vehicle.
6) Attach
lifting device to engine. Lift engine from front
supports.
Place support under bellhousing. Remove remaining
bellhousing
bolts. Remove engine.
Removal (Wrangler)
Pad
windshield frame using cloth. Raise hood, and rest it
against
windshield frame. Drain cooling system. Disconnect battery
cables.
Remove battery. Disconnect wiring from alternator, ignition
coil,
distributor, oil pressure sending unit and fuel injection
wiring
harness. Disconnect wires at starter solenoid and injector
harness
connector.
Disconnect
fuel line quick-connect couplings at fuel rail.
Remove fuel line
bracket from intake manifold. Remove engine ground
strap. Remove
air cleaner. Disconnect vacuum purge hose from vapor
canister
tee. Unplug idle speed actuator connector. Disconnect
throttle
cable and remove it from bracket.
Disconnect
throttle rod at bellcrank. Disconnect cruise
control cable (if
equipped). Unplug O2 sensor
connector. Disconnect
coolant hoses at radiator, intake manifold
and thermostat housing.
Remove fan
shroud and radiator. Remove fan and spacer. Install a 5/16
x
1/2" bolt through fan pulley into
water pump flange to maintain
pulley
and water pump alignment.
Remove
check valve from power brake booster (if equipped).
Disconnect
power steering hoses at steering gear (if equipped).
Drain
power steering
pump reservoir. Cap power steering hoses and fittings.
Tag and
disconnect any remaining hoses or electrical
connectors. Raise
and support vehicle. Disconnect exhaust pipe from
exhaust
manifold. Remove starter. Remove flywheel housing access
cover.
Remove engine mount through-bolts. Remove upper bellhousing
bolts.
Loosen lower bellhousing bolts.
Lower
vehicle. Attach lifting device to engine. Raise
engine from front
supports. Place support under bellhousing. Remove
remaining
bellhousing bolts. Lift engine from engine compartment.
Installation (All Models)
1) Remove engine mount cushions from brackets to aid
alignment of engine and transmission. Replace fuel line quick-connect "O" rings, spacers and retainers.
2) Be
careful not to damage trigger wheel on flywheel when
installing
engine into vehicle with automatic transmission. To
complete
installation, reverse removal procedure. Adjust throttle and
cruise
control linkage (if equipped). Tighten
bolts to specification.
See TORQUE
SPECIFICATIONS TABLE at the end of this article. Check
fluid
levels, and refill if necessary.
INTAKE MANIFOLD
Removal
Disconnect
negative battery cable. Remove air inlet from
throttle plate
assembly. Remove air cleaner. Disconnect throttle and
cruise
control (if equipped) cables. Disconnect line pressure cable to
A/T
(if equipped).
Unplug all
electrical connectors from intake manifold.
Release fuel system
pressure. See FUEL PRESSURE RELEASE. Disconnect
fuel line
quick-connect fittings at fuel rail. Loosen accessory drive
belt
and tensioner.
Remove
power steering pump and bracket. Wire pump aside.
Remove fuel
rail retaining bolts. Remove fuel rail and injector
assembly.
Raise and support vehicle. Disconnect exhaust pipe from
exhaust
manifold. Lower vehicle. Remove retaining bolts. Remove intake
and
exhaust manifolds as an assembly.
Installation
Fig. 2: Manifold Tightening Sequence Courtesy of Chrysler Corp.
Ensure
all gasket surfaces are clean. Install NEW gasket.
Install
exhaust manifold and tighten bolt No. 3 finger
tight. Install
intake manifold and
remaining bolts loosely. Replace fuel line quick-
connect "O"
rings, spacers and retainers.
Tighten
bolts in proper sequence to specification. See
Fig.
2. See TORQUE SPECIFICATIONS TABLE at the
end of this article.
Reverse removal
procedure to complete installation.
EXHAUST MANIFOLD
Removal & Installation
Remove exhaust manifold with intake manifold. See INTAKE MANIFOLD.
CYLINDER HEAD
Removal
Disconnect
negative battery cable. Drain cooling system.
Remove air cleaner
and fuel pipe. Remove molded hoses from cylinder
head cover.
Remove cylinder head cover.
Remove
rocker arms, bridges, pivots and push rods. See
ROCKER ARMS. Tag
all parts for reassembly reference. Loosen serpentine
drive belt
at power steering pump (if equipped) or at idler pulley.
Remove
alternator bracket-to-cylinder head bolt. Disconnect power
steering
pump bracket. DO NOT disconnect hoses. Wire power steering
pump
aside.
Remove manifolds. See INTAKE MANIFOLD and EXHAUST
MANIFOLD. Remove A/C compressor bracket bolts from cylinder head (if equipped). Loosen through bolt at bottom of A/C compressor bracket. Remove A/C compressor, and wire it aside.
Tag and
disconnect spark plug wires. Remove spark plugs.
Disconnect
temperature sending unit. Remove ignition coil and bracket
assembly.
Remove
cylinder head bolts. Pull bolt No. 14 out
as far as
possible and hold in position
using tape. Bolt No. 14 cannot be
removed
until head is moved forward. Remove cylinder head. Stuff
clean
lint-free shop towels into cylinder bores.
Inspection
Inspect
cylinder head for cracks and damage. Using
straightedge, check
cylinder head for warpage across bolt holes and
diagonals. Repair
or replace cylinder head if warpage exceeds
specification or
damage exists. See CYLINDER HEAD table under ENGINE
SPECIFICATIONS.
Cylinder
head bolts may only be reused once. If this is
first time
cylinder head has been removed, put a dab of paint on head
of
each bolt. If bolts already have paint on them or if it is
unknown
whether bolts have been used before, discard bolts and
replace them
with NEW head bolts.
Installation
Clean
carbon from combustion chambers and tops of pistons.
Ensure
all gasket surfaces, head bolts and head bolt holes are
clean.
Install NEW cylinder head gasket
with numbers or word "TOP" upward. DO
NOT apply gasket
sealant to cylinder head gasket. Ensure all holes are
aligned.
Install cylinder head bolt No. 14, and
hold in raised
position using tape.
Cylinder head bolt No. 14 cannot be
installed
after head is in position on
block. Install cylinder head.
Apply
sealant to threads of cylinder head bolt No. 11
before
installation. Install cylinder head bolts. Tighten all bolts
to
specification in 3 stages
and in sequence. During final tightening
stage, bolt No. 11
will be tightened to a lower torque than
others.
See Fig. 3. See TORQUE
SPECIFICATIONS TABLE at the end of this
article.
To install remaining components, reverse removal
procedure. Install all valve train components into original locations. Adjust A/T linkage. Refill cooling system. Start engine, and check for leaks.
Fig. 3: Cylinder Head Bolt Tightening Sequence Courtesy of Chrysler Corp.
FRONT COVER OIL SEAL
Removal
Disconnect
negative battery cable. Remove drive belts, fan
shroud, fan and
hub assembly. Remove accessory drive pulley. Remove
vibration
damper retaining bolt and washer.
Using
Puller (8068), remove vibration damper and
key.
Remove front cover oil seal.
Installation
Position
seal on Seal Installer (6139), with seal
open end
facing toward cover. Apply
thin coat of RTV sealant on outside
diameter of seal. Lightly
coat crankshaft with engine oil.
Position
installer over end of crankshaft. Insert draw
screw into end of
crankshaft. Tighten draw screw nut until seal is
fully seated in
front cover. Remover installer. Check seal for proper
installation.
To complete installation, reverse removal procedure.
TIMING CHAIN & SPROCKETS
Removal
Disconnect
negative battery cable. Remove drive belts, fan
shroud, fan and
hub assembly. Remove accessory drive pulley. Remove
vibration
damper retaining bolt and washer.
Using
Puller (8068), remove vibration damper and
key.
Remove alternator bracket assembly and A/C compressor
bracket (if
equipped). Remove oil pan-to-front cover bolts.
Remove cover-to-block
retaining bolts.
Remove front cover. Take care that tension spring and
thrust
pin do not fall out of camshaft preload bolt into oil pan.
Remove
tension spring and thrust pin from preload bolt. Rotate
crankshaft
until timing marks on sprockets are aligned. See Fig. 4.
Remove
preload bolt. Remove timing chain and sprockets as an assembly.
Installation
Install
timing chain and sprockets as an assembly. Ensure
timing
marks align. Lubricate tension spring, thrust pin and thrust
pin
bore with Mopar Engine Oil Supplement (4318002)
before
installation. Install preload bolt and
washer. Tighten to
specification. See TORQUE SPECIFICATIONS TABLE
at the end of this
article.
Verify proper installation by rotating crankshaft until
timing mark on camshaft is at approximately one o’clock position. Timing sprockets are installed correctly if 15 timing chain pins are between timing marks on both sprockets.
3) Install NEW front cover oil seal. Cut oil pan gasket tabs even with face of cylinder block. Remove tabs. Remove gasket from oil pan. Remove crankshaft oil seal from front cover. Clean front cover, oil pan and cylinder block gasket surfaces. Install front cover. To install remaining components, reverse removal procedure. See TORQUE SPECIFICATIONS TABLE at the end of this article.
Fig. 4: Aligning Sprocket Timing Marks Courtesy of Chrysler Corp.
ROCKER ARMS
NOTE: All reused camshaft/valve train components must be reinstalled in original locations.
Removal
Remove valve cover. Alternately loosen rocker arm cap screws one turn at a time to prevent damaging bridges. Remove bridges, pivots, rocker arms and push rods. Tag all parts for installation reference.
Installation
1) Install
all reused components into original locations.
Ensure
bottom ends of push rods are centered in valve lifters.
Lubricate
pivot contact area of rocker arms with Mopar Engine Oil
Supplement
(4318002). Install cap screws loosely, and
then tighten
alternately one turn at a
time to specification. See
TORQUE SPECIFICATIONS TABLE at the end of this article.
2) Reverse
removal procedure to complete installation. Pour
remaining
engine oil supplement over entire valve train. Supplement
must
remain in engine oil for at least 1000 miles
(1600 km) . Refill
cooling
system. Adjust ignition timing. Check for leaks.
CAMSHAFT
Removal
Disconnect
negative battery cable. Drain cooling system.
Remove
radiator and A/C condenser (if equipped) , but
DO NOT discharge
system. Mark
distributor and engine block for installation reference.
Remove
distributor and ignition wiring. Remove cylinder head. See
CYLINDER
HEAD.
Remove valve lifters using Hydraulic Valve Lifter
Remover/Installer (C-4129-A). Tag each valve lifter for installation reference. Remove timing chain and sprockets. See
TIMING CHAIN & SPROCKETS. Remove front bumper and/or grille as required. Remove camshaft.
Inspection
Inspect lobes, journals, bearings and distributor drive gear for wear. Inspect valve lifters for abnormal wear. If camshaft sprocket or chain rubs against engine front cover, examine oil pressure relief holes in rear camshaft journal and ensure they are free of debris. Replace components as necessary. If camshaft requires replacement, valve lifters MUST also be replaced.
Installation
Lubricate
camshaft and dip valve lifters into MOPAR Engine
Oil Supplement
(4318002) . Install camshaft. Reverse
removal procedure
to complete installation.
Pour
remaining engine oil supplement over entire valve
train.
Supplement must remain in engine oil for at least 1000 miles
(1600 km). Refill cooling system. Adjust ignition timing. Check for leaks.
REAR CRANKSHAFT OIL SEAL
Removal
Remove
transmission and flywheel or torque converter
plate. Remove oil
pan. See OIL PAN removal in this section. Remove
rear
main bearing cap (No. 7).
Push upper
seal out of groove. Ensure crankshaft and seal
groove are not
damaged. Remove lower half of seal from bearing cap.
Installation
Remove the
rear main bearing cap. Wipe the seal surface
area of the
crankshaft until it is clean. Apply a thin coat of engine
oil.
Position the upper seal into the cylinder block. The lip of the
seal
faces toward the front of the engine.
Place
lower half of seal into bearing cap No. 7. Coat
both
sides of the lower seal end tabs
w/Jeep Gasket-in-a-Tube, or
equivalent. Do not apply sealant to
the lip of the seal. Coat the
outer curved surface of the lower
seal with soap and the lip of the
seal
w/engine oil.
3) Position
the lower seal into the bearing cap recess and
seat
it firmly. Be sure seal is flush with cylinder block pan rail.
Apply
Loctite 515, or
equivalent on rear bearing cap. The bead should
be
0.125" (3 mm)
thick. Do not apply Loctite 515, or
equivalent to lip
of seal.
CAUTION: Do not apply Loctite 515, or equivalent to lip of seal.
4) Install
the rear main bearing cap. Do not strike cap more
than twice for
proper engagement. Tighten all main bearing bolts to 80
ft-lbs
(108 Nm) torque. Install oil pan gasket and
oil pan. Install
transmission inspection
plate.
WATER PUMP
Removal
Disconnect negative battery cable. Drain coolant. Remove fan shroud retaining screws and drive belts. Remove fan. Disconnect heater hoses and lower radiator hose at water pump. Remove power steering pump bracket (if equipped) at water pump boss. Remove retaining bolts and water pump.
Installation
Clean all gasket surfaces. Install water pump. Tighten bolts to specification. See TORQUE SPECIFICATIONS TABLE at the end of this article. Ensure pump turns freely. Ensure belt is correctly installed or engine may overheat because pump rotates in wrong direction. To complete installation, reverse removal procedures. Fill cooling system.
OIL PAN
Removal
Disconnect
negative battery cable. Raise and support
vehicle at side sills.
Drain engine oil. Disconnect exhaust pipe at
exhaust manifold.
Disconnect exhaust hanger at catalytic converter.
Lower exhaust
pipe. Remove starter. Remove flywheel access cover.
Position
jackstand directly under vibration damper. Place
wooden block
between vibration damper and jackstand. Remove through
bolts from
engine mounts. Raise engine enough to remove oil pan.
Remove oil
pan retaining bolts. Remove oil pan by sliding it to rear.
Installation
1) Ensure all gasket surfaces are clean. Fabricate 4
alignment dowels from 1 1/2 x 1/4" bolts. Cut heads off bolts and cut slot in end of bolts to allow removal with screwdriver. Install 2 dowels in timing cover and 2 dowels in block. Slide gasket over dowels into position against block and timing cover.
2) Install
oil pan. Install sufficient bolts to hold oil pan
in
place. Remove alignment dowels. Install remaining oil pan bolts
and
tighten to specification. See TORQUE
SPECIFICATIONS TABLE at the end
of this
article. To complete installation, reverse removal procedure.
Fill
crankcase. Start engine. Check for leaks.
OVERHAUL
CYLINDER HEAD
Cylinder Head Service
Inspect for cracks in combustion chambers, coolant passages, ports and exhaust valve seats. Using straightedge, check cylinder head for warpage across bolt holes and diagonals. Resurface or replace
cylinder head if warpage exceeds specification or damage exists. See CYLINDER HEAD table under ENGINE SPECIFICATIONS.
Valve Springs
Use Valve Spring Tester (C-647 or J-22738-02) to test each valve spring. Measure free length of each valve spring. Replace valve springs that do not meet specifications. See VALVES & VALVE SPRINGS table under ENGINE SPECIFICATIONS.
Valve Stem Oil Seals
Replace valve stem oil seals if they have deteriorated or whenever valves are serviced. Oil seals are marked "INT" and "EXH" for intake and exhaust valves, respectively.
Valve Guides
Measure diameter of valve guide approximately 3/8" (10 mm) from valve spring side of head, both parallel and at right angles to long axis of head. If difference between measurements exceeds .0025" (.063 mm), or if diameter exceeds specification by .003" (.08 mm), ream valve guide for oversize valve stem. Valve seats must be refaced after reaming valve guides. See CYLINDER HEAD table under ENGINE SPECIFICATIONS.
Valve Seats
Reface valve seats to specification. Remove only enough metal to provide smooth finish. Use tapered stones to obtain specified seat width. See Fig. 5. Seat width runout should not exceed .0025" (.063 mm) after refacing. See CYLINDER HEAD table under ENGINE SPECIFICATIONS.
Valves
Reface valves to specification. At least .031" (.79 mm) margin must remain after refacing valve. Valve stem tip can be resurfaced and chamfered when worn. DO NOT remove more than .01" (.25 mm). See VALVES & VALVE SPRINGS table under ENGINE SPECIFICATIONS.
91C14300
Fig. 5: Measuring Valve Seat Dimensions Courtesy of Chrysler Corp.
VALVE TRAIN
Rocker Arms
Inspect pivot and valve stem contact surfaces of each rocker arm. Replace any rocker arm that is scuffed, pitted, cracked or excessively worn.
Push Rods
Inspect push rods for excessive wear. If wear is excessive because of lack of oil, replace and inspect corresponding valve lifter for excessive wear. Roll push rods on a flat surface to check for straightness. Replace push rod and/or valve lifter, if necessary. If wear exists along length of push rod, inspect cylinder head for obstruction.
CYLINDER BLOCK ASSEMBLY
Piston & Rod Assembly
Position
piston on support. See Fig. 6. Press
piston pin
from piston. Discard pin.
Piston pin cannot be reused after removal.
Inspect piston pin
bore in connecting rod for nicks and burrs, and
remove
as necessary. Clean and dry piston pin bore and NEW piston pin.
Clean
piston pin bore and replacement piston pin. Piston
and piston pin
must be at room temperature when measuring fit. Piston
pin should
fall through piston at room temperature. If pin jams in pin
bore,
replace piston.
Ensure
arrow on piston crown is pointing up. Insert piston
pin through
piston pin bore and into connecting rod pin bore.
Assemble
connecting rod and piston so oil squirt hole faces
camshaft and arrow
on piston points to front of engine when
installed.
Fig. 6: Removing & Installing Piston Pin Courtesy of Chrysler Corp.
4) Press pin through rod and piston until pilot indexes with mark on support. Pin should be centered in rod. Piston pin
installation requires approximately 2000 lbs. (900 kg) of force. Replace connecting rod if noticeably less force is required, or if rod moves on pin.
Fitting Pistons
Measure cylinder bore 2 5/16" (59 mm) below top of bore. Measure piston diameter at right angle to piston pin at center line of pin. Piston clearance is difference between measurements. Pistons up to .004" (.10 mm) undersize may be enlarged by knurling or shot peening. Replace pistons if they are .004" (.10 mm) or more undersize.
Piston Rings
Install piston rings. Ensure ring end gap and side clearance are within specification. Install compression rings with dot(s) on ring surface toward top of piston. DO NOT interchange compression rings. Top ring has Gray scraping surface; second ring has Black scraping surface. Position ring end gaps in specified area. Ring gaps may vary 20 degrees from positions illustrated. See Fig. 7. See PISTONS, PINS & RINGS table under ENGINE SPECIFICATIONS.
— Top Compression
Ring
Bottom Compression — Ring
93H75900
Fig. 7: Positioning Piston Ring Gaps Courtesy of Chrysler Corp.
Rod Bearings
Inspect
bearings for wear or damage. Replace as necessary.
Using
Plastigage, check bearing clearance. See CRANKSHAFT, MAIN
&
CONNECTING ROD BEARINGS table
under ENGINE SPECIFICATIONS. Bearings
are
available for standard and undersize applications.
If
necessary, different size upper and lower bearings may
be
combined to obtain correct oil clearance. Lubricate bearing
surfaces
with oil before installation. Tighten bolts to specification.
Check
rod side play. Rotate crankshaft to ensure freedom of movement.
See
TORQUE SPECIFICATIONS TABLE at the end of this article.
See
CRANKSHAFT, MAIN & CONNECTING
ROD BEARINGS table.
NOTE: Avoid combining bearing inserts in excess of .001" (.03 mm) difference in size. Odd size inserts must be on bottom (rod cap) side.
Crankshaft & Main Bearings
1) Inspect bearings for wear or damage. Replace as necessary. Using Plastigage, check bearing clearance. See CRANKSHAFT, MAIN & CONNECTING ROD BEARINGS table under ENGINE SPECIFICATIONS. Bearings are available in standard and undersize. If necessary, different size upper and lower bearings may be installed to obtain correct oil clearance. Lubricate bearings before installation.
NOTE: If different size bearings are used, odd size bearings must all be uniform in location (upper or lower). DO NOT use bearings with a thickness difference exceeding .001" (.03 mm) .
2) Install upper bearing inserts. Install bearing caps and lower inserts. Tighten bearing caps in 3 stages to specification. Rotate crankshaft to ensure freedom of movement after tightening each cap. See TORQUE SPECIFICATIONS TABLE at the end of this article. See CRANKSHAFT, MAIN & CONNECTING ROD BEARINGS table.
Thrust Bearing
Check crankshaft end play. If end play is not within
specification, replace thrust bearing. If end play is still not within specification, replace crankshaft.
Cylinder Block
Thoroughly
clean all gasket surfaces. Using a tap, clean
head
bolt holes. Clean oil gallery by blowing compressed air into
oil
filter adapter, filter by-pass, oil
gallery and crankshaft oil feed
holes.
Measure
cylinder bore diameter crosswise to cylinder block
about
1/2" below top of bore. Repeat
measurement at bottom of bore.
Subtract smaller diameter from
larger diameter to determine taper.
Repeat
measurements for each cylinder.
Repeat
measurements with measuring device rotated 120
degrees.
Repeat this step for a total of 3 measurements.
Cylinder out-
of-round is difference between measurements. Repeat
for each cylinder.
Bore
and hone cylinders for oversize pistons if taper or
out-of-round
exceeds specification. Move hone up and down to provide a
60-degree
crosshatch pattern. DO NOT use a rigid hone or exceed 10
strokes
per cylinder. See CYLINDER BLOCK table under ENGINE
SPECIFICATIONS.
LUBRICATION
ENGINE OILING
An oil pump driven by distributor supplies oil through a full-flow oil filter into an internal oil passage. This passage provides oil to valve lifter bores and then to camshaft and crankshaft bearings. Oil then flows from hydraulic valve lifters through push rods to rocker arms.
Crankcase Capacity
Oil capacity is 6.0 qts. (5.7L) with filter change.
Oil Pressure
Minimum oil pressure should be 13 psi (89.6 kPa) at 600 RPM. Normal oil pressure should be 37-75 psi (255.1-517.1 kPa) above 1600 RPM. Oil pressure relief is 75 psi (517.1 kPa).
OIL PUMP
Removal & Disassembly
Remove mounting bolts and oil pump. DO NOT move oil pick-up pipe in pump body. If oil pick-up pipe is moved, pick-up pipe MUST be replaced to ensure an airtight seal. Remove pump cover. Disassemble pump.
Inspection
Inspect for wear or damage. Place Plastigage across full width of each gear. Install cover temporarily and tighten bolts to 70 INCH lbs. (8 N.m). Remove cover. Examine Plastigage to determine end clearance. Measure clearance between each tooth and oil pump body directly opposite point of mesh. Replace oil pump if not within specifications. See OIL PUMP SPECIFICATIONS table.
OIL PUMP SPECIFICATIONS TABLE
Application In. (mm)
Gear End Clearance 002-.006 (.05-.15)
Gear-to-Body Clearance 002-.004 (.05-.10)
Reassembly & Installation
Apply
sealant to pick-up pipe and pump cover area prior to
installation.
To install pick-up pipe use Pipe Installer (7624) .
Ensure
pick-up pipe support bracket aligns with pump cover bolt. If
relief
valve is replaced, ensure replacement valve is the same
diameter
as that removed.
Fill pump
cavity with petroleum jelly. Install cover.
Tighten cover bolts
to specification. Check pump gears for freedom of
rotation.
Install NEW gasket and oil pump. Tighten retaining bolts
to
specification. See TORQUE SPECIFICATIONS table.
TORQUE SPECIFICATIONS
TORQUE SPECIFICATIONS TABLE
Application Ft. Lbs. (N.m)
Camshaft Sprocket Preload Bolt 80 (108)
Connecting Rod Cap Nut 33 (45)
Converter-To-Flexplate Bolts (1)
Cylinder Head Bolts (2)
Stage 1 22 (30)
Stage 2 45 (61)
Stage 3 (2) 110 (149)
Exhaust Manifold Bolts (3)
Bolts No. 1-5 24 (33)
Bolts No. 6 & 7 17 (23)
Bolts No. 8-11 24 (33)
Fan Bolt 18 (24)
Flexplate-To-Converter Bolts 40 (54)
Flexplate-To-Crankshaft Bolts 55 (75)
Flywheel-To-Crankshaft Bolts (1)
Intake Manifold Bolts (3)
Bolts No. 1-5 24 (33)
Bolts No. 6 & 7 17 (23)
Bolts No. 8-11 24 (33)
Main Bearing Cap Bolts
Stage 1 40 (54)
Stage 2 70 (95)
Stage 3 80 (108)
Oil Pump Retaining Bolts
Long 17 (23)
Short 10 (14)
Pulley-To-Vibration Damper Bolts 20 (27)
Rocker Arm Bolts 21 (29)
Starter Bolts 33 (45)
Vibration Damper Bolt (4) 80 (108)
Water Pump Bolts 22 (30)
INCH Lbs. (N.m)
Front Cover Bolts 62 (7)
Oil Pan Bolts
1/4" X 20 114 (13)
5/16" X 18 156 (18)
Oil Pump Cover Bolts 70 (8)
Valve Cover Bolts 80 (9)
- Information is not available from manufacturer.
- All bolts except No. 11. Tighten bolt No. 11 to
100 ft. lbs. (136 N.m) See Fig. 3.
- Tighten in sequence. See Fig. 2.
- With bolt cleaned and threads lubricated with oil.
ENGINE SPECIFICATIONS
GENERAL ENGINE SPECIFICATIONS
GENERAL SPECIFICATIONS
Application
Specification
Displacement 242 Cu. In. (4.0L)
Bore 3.88" (98.5mm)
Stroke 3.44" (87.4mm)
Compression Ratio 8.8:1
Fuel System PFI
Horsepower @ RPM
Except Wrangler 190 @ 4750
Wrangler 180 @ 4750
Torque Ft. Lbs. @ RPM
Except Wrangler 225 @ 4000
Wrangler 220 @ 4000
CRANKSHAFT, MAIN & CONNECTING ROD BEARINGS SPECIFICATIONS
CRANKSHAFT, MAIN & CONNECTING ROD BEARINGS TABLE
Application
In. (mm)
Crankshaft
End Play 0015-.0065 (.038-.165)
Runout ( 1)
Main Bearings
Journal Diameter 2.4996-2.5001 (63.489-63.502)
Journal Out-Of-Round 0005 (.013)
Journal Taper 0005 (.013)
Oil Clearance 0010-.0025 (.025-.064)
Connecting Rod Bearings
Journal Diameter 2.0934-2.0955 (53.172-53.226)
Journal Out-Of-Round 0005 (.013)
Journal Taper 0005 (.013)
Oil Clearance 0015-.0025 (.038-.064)
(1) - Information is not available from manufacturer.
CONNECTING RODS SPECIFICATIONS
CONNECTING RODS TABLE
Application
In. (mm)
Bore Diameter
Pin Bore 9288-.9298 (23.591-23.617)
Crankpin Bore 2.2080-2.2085 (56.083-56.096)
Center-To-Center Length 6.123-6.127 (155.52-155.63)
Maximum Bend 003 (.08)
Maximum Twist 006 (.15)
Side Play 010-.019 (.25-.48)
PISTONS, PINS & RINGS SPECIFICATIONS
PISTONS, PINS & RINGS TABLE
Application In. (mm)
Pistons
Clearance 0013-.0021 (.033-.053)
Diameter ( 1)
Pins
Diameter 9306-.9307 (23.637-23.640)
Piston Fit 0003-.0007 (.007-.018)
Rod Fit Press Fit
Rings No. 1
End Gap 010-.020 (.25-.51)
Side Clearance 0010-.0032 (.025-.081)
No. 2
End Gap 010-.020 (.25-.51)
Side Clearance 0017-.0032 (.043-.081)
No. 3 (Oil)
End Gap 010-.025 (.25-.64)
Side Clearance 001-.009 (.03-.23)
(1) - Information is not available from manufacturer.
Replace pistons if piston clearance exceeds .004" (.10 mm).
CYLINDER BLOCK SPECIFICATIONS
CYLINDER BLOCK TABLE
Application In. (mm)
Cylinder Bore
Standard Diameter 3.8751-3.8775 (98.427-98.488)
Maximum Taper 001 (.03)
Maximum Out-Of-Round 001 (.03)
Minimum Deck Height 9.429 (239.49)
Maximum Warpage 008 (.20)
VALVES & VALVE SPRINGS SPECIFICATIONS
VALVES & VALVE SPRINGS TABLE
Application Specification
Intake Valves
Face Angle 45
Head Diameter 1.91" (48.5 mm)
Minimum Margin 031" (.79 mm)
Minimum Refinish Length 4.822" (122.47 mm)
Stem Diameter 312" (7.92 mm)
Valve Tip Maximum Refinish 010" (.25 mm)
Exhaust Valves
Face Angle 45
Head Diameter 1.5" (38.1 mm)
Minimum Margin 031" (.79 mm)
Minimum Refinish Length 4.837" (122.86 mm)
Stem Diameter 312" (7.92 mm)
Valve Tip Maximum Refinish 010" (.25 mm)
Valve Springs
Free Length 1.82" (46.2 mm)
Installed Height 1.625" (41.29 mm)
Out-Of-Square ( 1)
Spring Pressure (2)
Valve Closed 66-74 @ 1.625 (29.94-33.56 @ 41.28)
Valve Open 205-220 @ 1.2 (92.98-99.78 @ 30.48)
- Information is not available from manufacturer.
- Lbs. @ In. (kg @ mm).
CYLINDER HEAD SPECIFICATIONS
CYLINDER HEAD TABLE
Application Specification
Cylinder Head Height ( 1)
Maximum Warpage 008" (.20 mm)
Valve Seats Intake Valve
Seat Angle 44.5
Seat Width 040-.060" (1.02-1.52 mm)
Maximum Seat Runout 0025" (.064 mm)
Seat Bore Diameter ( 1)
Exhaust Valve
Seat Angle 44.5
Seat Width 040-.060" (1.02-1.52 mm)
Maximum Seat Runout 0025" (.064 mm)
Seat Bore Diameter ( 1)
Valve Guides Intake Valve
Valve Guide I.D 312" (7.9 mm)
Valve Stem-To-Guide
Oil Clearance 001-.003" (.03-.08 mm)
Exhaust Valve
Valve Guide I.D 312" (7.9 mm)
Valve
Stem-To-Guide
Oil Clearance
001-.003" (.03-.08 mm)
(1) - Information is not available from manufacturer.
CAMSHAFT SPECIFICATIONS
CAMSHAFT TABLE
Application In. (mm)
Bore Diameter ( 1)
End Play (2) 0 (0)
Journal Diameter
No. 1 2.029-2.030 (51.54-51.56)
No. 2 2.019-2.020 (51.28-51.31)
No. 3 2.009-2.010 (51.03-51.05)
No. 4 1.999-2.000 (50.78-50.80)
Journal Runout (3)
Lobe Height ( 1)
Lobe Lift 253 (6.43)
Oil Clearance 001-.003 (.03-.08)
- Information is not available from manufacturer.
- Engine running.
- Information is not available from manufacturer.
Manufacturer specifies .001" (.03 mm) maximum base circle runout.
VALVE LIFTERS SPECIFICATIONS
VALVE LIFTERS TABLE
Application In. (mm)
Bore Diameter 9055-.9065 (22.999-23.025)
Lifter Diameter 9040-.9045 (22.962-22.974)
Oil Clearance 001-.0025 (.025-.063)
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