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Online Manual Jeep > Jeep Cherokee XJ > 1993 > 40L six

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:

  1. "B" indicates all cylinder bores are .010" (.25 mm) oversize.

  2. "C" indicates all camshaft bearing bores are .010" (.25 mm)
    oversize.

  3. "M" indicates all main bearing journals are .010" (.25 mm)
    undersize.

  4. "P" indicates one or more connecting rod journals are .010"
    (.25 mm) undersize.

  5. "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)

  1. 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.

  2. 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.

  1. 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.

  2. 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.

  3. 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)

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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

  1. 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).

  2. 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.

  3. 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.


  1. 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.

  2. 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

  1. Disconnect negative battery cable. Drain cooling system.
    Remove air cleaner and fuel pipe. Remove molded hoses from cylinder
    head cover. Remove cylinder head cover.

  2. 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.

  3. 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.

  1. Tag and disconnect spark plug wires. Remove spark plugs.
    Disconnect temperature sending unit. Remove ignition coil and bracket
    assembly.

  2. 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

  1. 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.

  2. 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

  1. 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.

  2. 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.

  3. 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

  1. Disconnect negative battery cable. Remove drive belts, fan
    shroud, fan and hub assembly. Remove accessory drive pulley. Remove
    vibration damper retaining bolt and washer.

  2. Using Puller (8068), remove vibration damper and key.
    Remove front cover oil seal.

Installation

  1. 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.

  2. 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

  1. Disconnect negative battery cable. Remove drive belts, fan
    shroud, fan and hub assembly. Remove accessory drive pulley. Remove
    vibration damper retaining bolt and washer.

  2. 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

  1. 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.

  2. Verify proper installation by rotating crankshaft until

timing mark on camshaft is at approximately one oclock 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

  1. 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.

  2. 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

  1. Lubricate camshaft and dip valve lifters into MOPAR Engine
    Oil Supplement
    (4318002) . Install camshaft. Reverse removal procedure
    to complete installation.

  2. 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

  1. 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).

  2. Push upper seal out of groove. Ensure crankshaft and seal
    groove are not damaged. Remove lower half of seal from bearing cap.

Installation

  1. 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.

  2. 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

  1. 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.

  2. 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

  1. 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.

  2. 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.

  3. 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

  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 for standard and undersize applications.

  2. 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

  1. 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.

  2. 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.

  3. 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.

  4. 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

  1. 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.

  2. 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)

  1. - Information is not available from manufacturer.

  2. - All bolts except No. 11. Tighten bolt No. 11 to

100 ft. lbs. (136 N.m) See Fig. 3.

  1. - Tighten in sequence. See Fig. 2.

  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)

  1. - Information is not available from manufacturer.

  2. - 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)

  1. - Information is not available from manufacturer.

  2. - Engine running.

  3. - 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)