4.0l Engine Jeep Grand Cherokee WJ

ENGINE IDENTIFICATION

Note. For repair procedures not covered in this article, see ENGINE OVERHAUL PROCEDURES article in GENERAL INFORMATION.

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. See ENGINE IDENTIFICATION CODE table.

ENGINE IDENTIFICATION CODE

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

VALVE CLEARANCE ADJUSTMENT

Engine is equipped with hydraulic valve lifters. Valve adjustment is not required.

THROTTLE CABLE ADJUSTMENT

Shift transmission into Park (A/T). Ensure engine is off. Disconnect throttle cable from throttle lever. Press cable release button and adjust cable end socket to center of ball on lever. Connect cable to throttle lever.

TROUBLE SHOOTING

Note. To trouble shoot mechanical engine components, see appropriate table in TROUBLE SHOOTING article in GENERAL INFORMATION.

REMOVAL & INSTALLATION

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

1. Remove fuel filler cap and open tank flap valve to relieve tank pressure. Remove fuel pump relay from Power Distribution Center (PDC). PDC is located in engine compartment near battery. Start and run engine until it stalls. Attempt restarting engine until it will no longer start. Turn ignition off. Unplug connector from any injector.
2. Connect an 18-gauge (or smaller) jumper between either injection terminal and positive battery terminal. Connect one end of a second jumper to remaining injector terminal.
3. Momentarily touch other end of second jumper to negative battery terminal (no more than 4 seconds). Place a rag or towel around quick-connect fitting located at fuel rail.
4. If vehicle is equipped with a single-tab type fitting, clean fitting of any debris. Press release tab on side of fitting to release pull tab. While pressing release tab on side of fitting, use a small screwdriver to pry up pull tab. Raise pull tab until it separates from quick-connect fitting. Discard old pull tab.
5. If vehicle is equipped with a 2-tab type fitting, clean fitting of any debris. Squeeze plastic retainer tabs against sides of quick-connect fitting, and pull fitting.
6. If vehicle is equipped with a retainer ring type fitting, clean fitting of any debris. Firmly push fitting toward component being serviced while firmly pushing Black, plastic retainer ring into fitting. With plastic ring depressed, pull fitting from component.
7. If vehicle is equipped with latch clip, clean fitting of any debris. Using a screwdriver, pry up on and slide latch clip. Remove clip. Using Fuel Line Removal Tool (FIH-9055-1), release locking fingers in end of line. Pull fuel line from fuel rail. On all models, return fuel pump relay to PDC. 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

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 engine off and allow to cool. Recheck coolant level in reserve/overflow tank as necessary.

POWER STEERING BLEEDING

1. Fill pump to COLD level on dipstick, and let fluid settle for at least 2 minutes. Start engine and let run for a few seconds, then turn engine off. Add fluid if necessary. Repeat procedure until fluid level remains constant after running engine.
2. Raise and support front wheels. Slowly turn steering wheel right and left, lightly contacting wheel stops. Turn wheel at least 20 times. Check fluid level and add if necessary.
3. Lower vehicle, start engine and turn steering wheel slowly from lock to lock. Stop engine, check fluid level and add if necessary. If fluid is extremely foamy or milky looking, allow vehicle to stand a few minutes and repeat bleeding procedure.

Removal (Cherokee & Grand Cherokee)

1. Remove hood. Disconnect battery cables. Remove battery. Remove air cleaner. Unplug 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.
3. Disconnect line pressure cable to A/T (if equipped). Release fuel pressure. See «FUEL PRESSURE RELEASE»(/jeep/grand-cherokee/wj-1998-2004/remont/mechanical/#40l-engine__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. Disconnect power steering hoses at steering gear (if equipped). Drain power steering pump reservoir. Cap power steering hoses and fittings.
4. 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 sensor. Disconnect engine speed sensor.
5. 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. Remove air cleaner resonator and ducts. Drain cooling system. Disconnect battery cables. Remove battery. Discharge A/C system (if equipped) using approved refrigerant recovery/recycling equipment. Disconnect A/C compressor hose. Disconnect wiring from generator, ignition coil, distributor, oil pressure sending unit and fuel injection wiring harness. Disconnect wires at starter solenoid and injector harness connector.
2. Relieve fuel pressure. Disconnect fuel line quick-connect couplings at fuel rail. Remove fuel line bracket from intake manifold. Remove engine ground strap. Disconnect vacuum purge hose from vapor canister "T". Unplug idle speed actuator connector. Disconnect throttle cable and remove from bracket.
3. Disconnect throttle rod at bellcrank. Disconnect cruise control cable (if equipped). Unplug oxygen 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. 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. DO NOT 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. See «THROTTLE CABLE ADJUSTMENT»(/jeep/grand-cherokee/wj-1998-2004/remont/mechanical/#40l-engine__throttle-cable-adjustment) under ADJUSTMENTS. Bleed power steering system. See «POWER STEERING BLEEDING»(/jeep/grand-cherokee/wj-1998-2004/remont/mechanical/#40l-engine__power-steering-bleeding) . Tighten bolts to specification. See «TORQUE SPECIFICATIONS»(/jeep/grand-cherokee/wj-1998-2004/remont/mechanical/#40l-engine__torque-specifications) . Check fluid levels, and refill if necessary.

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»(/jeep/grand-cherokee/wj-1998-2004/remont/mechanical/#40l-engine__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

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. (Scheme 1) See «TORQUE SPECIFICATIONS»(/jeep/grand-cherokee/wj-1998-2004/remont/mechanical/#40l-engine__torque-specifications). Reverse removal procedure to complete installation.

Scheme 1

Remove exhaust manifold with intake manifold. See INTAKE MANIFOLD .

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»(/jeep/grand-cherokee/wj-1998-2004/remont/mechanical/#40l-engine__rocker-arms) . Tag all parts for reassembly reference. Loosen serpentine drive belt at power steering pump (if equipped) or at idler pulley. Remove generator 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»(/jeep/grand-cherokee/wj-1998-2004/remont/mechanical/#40l-engine) and «EXHAUST MANIFOLD»(/jeep/grand-cherokee/wj-1998-2004/remont/mechanical/#40l-engine) . Remove A/C compressor bracket bolts (if equipped) from cylinder head. Loosen through bolt at bottom of A/C compressor bracket. Remove A/C compressor, and wire aside.
4. Tag and disconnect spark plug wires. Remove spark plugs. Disconnect temperature sending unit. Remove ignition coil and bracket assembly.
5. 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. To exclude debris and contamination, place 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»(/jeep/grand-cherokee/wj-1998-2004/remont/mechanical/#40l-engine) table under ENGINE SPECIFICATIONS.
2. Cylinder head bolts may only be reused once. If this is first time cylinder head has been removed, mark each bolt head with paint. If bolts are already marked or if it is unknown whether head bolts have been used before, discard and replace with NEW head bolts.

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 requires less torque than the others. (Scheme 2) See «TORQUE SPECIFICATIONS»(/jeep/grand-cherokee/wj-1998-2004/remont/mechanical/#40l-engine__torque-specifications).
3. To install remaining components, reverse removal procedure. Install all valve train components into original locations. Adjust A/T linkage. Refill and bleed cooling system. See «COOLING SYSTEM BLEEDING»(/jeep/grand-cherokee/wj-1998-2004/remont/mechanical/#40l-engine__cooling-system-bleeding). Start engine, and check for leaks.

Scheme 2

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 (7697), remove vibration damper and key. Remove front cover oil seal.

1. Position seal on Seal Installer (6139), with open end of seal 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. Remove installer. Check seal for proper installation. To complete installation, reverse removal procedure.

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 (7697), remove vibration damper and key. Remove generator bracket assembly and A/C compressor bracket (if equipped). Remove oil pan-to-front cover bolts. Remove front cover-to-block bolts. Carefully remove front cover, ensuring tension spring and thrust pin do not fall out of camshaft preload bolt into oil pan.
3. Remove tension spring and thrust pin from preload bolt. Rotate crankshaft until timing marks on sprockets are aligned. (Scheme 3) Remove preload bolt. Remove timing chain and sprockets as an assembly.

1. Install timing chain and sprockets as an assembly. Ensure timing marks align. Apply sealant to crankshaft keyway and install into crankshaft. Lubricate tension spring, thrust pin and thrust pin bore with MOPAR Engine Oil Supplement (4318002) before installation. Install camshaft sprocket bolt and washer. Tighten to specification. See «TORQUE SPECIFICATIONS»(/jeep/grand-cherokee/wj-1998-2004/remont/mechanical/#40l-engine__torque-specifications).
2. Verify proper installation by rotating crankshaft 2 revolutions. Camshaft and crankshaft timing marks should be aligned. (Scheme 3)
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»(/jeep/grand-cherokee/wj-1998-2004/remont/mechanical/#40l-engine__torque-specifications).

Scheme 3

Note. All reused camshaft/valve train components must be reinstalled in original locations.

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.

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»(/jeep/grand-cherokee/wj-1998-2004/remont/mechanical/#40l-engine__torque-specifications) .
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. Refill cooling system. Adjust ignition timing. Check for leaks.

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»(/jeep/grand-cherokee/wj-1998-2004/remont/mechanical/#40l-engine) .
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»(/jeep/grand-cherokee/wj-1998-2004/remont/mechanical/#40l-engine) . Remove front bumper and/or grille as required. Remove camshaft.

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.

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. Refill cooling system. Adjust ignition timing. Check for leaks.

Remove transmission inspection cover. Remove oil pan. See OIL PAN . Remove main bearing cap brace. Remove rear main bearing cap, and push upper seal from groove. Ensure crankshaft and seal groove are not damaged. Remove lower half of seal from bearing cap.

1. Clean surface of crankshaft. Apply thin coat of oil to crankshaft and seal lip. Position upper seal into groove in cylinder block so lip of seal faces front of engine. Place lower half into bearing cap.
2. Coat both ends of lower seal end tabs with sealant. DO NOT apply sealant to lip of seal. Coat outer curved surface of lower seal with soap. Coat lip of seal with engine oil. Position lower seal into bearing cap recess and seat firmly. Coat both chamfered edges of rear main bearing cap with sealant. DO NOT apply sealant to mating surfaces of bearing cap or cylinder block.
3. Install rear main cap in original position. Tighten bolts in 3 stages to specification. See «CRANKSHAFT & MAIN BEARINGS»(/jeep/grand-cherokee/wj-1998-2004/remont/mechanical/#40l-engine__crankshaft-main-bearings) under CYLINDER BLOCK ASSEMBLY under OVERHAUL. To install remaining components, reverse removal procedure.

Note. A counterclockwise rotation water pump is used. Letter "R" is stamped on back of pump impeller. Previous engines may have used a forward rotating pump. Ensure correct pump is used for replacement.

Disconnect negative battery cable. Drain cooling system. Loosen, but do not remove, water pump pulley mounting nuts. Remove accessory drive belt. Remove power steering pump. Remove fan shroud. Remove fan assembly. Disconnect heater hoses and lower radiator hose at water pump. Remove water pump retaining bolts. Remove water pump. Note that one bolt is longer than the others.

1. Clean all gasket surfaces. Install water pump. Tighten bolts to specification. See «TORQUE SPECIFICATIONS»(/jeep/grand-cherokee/wj-1998-2004/remont/mechanical/#40l-engine__torque-specifications) . Ensure pump turns freely. Ensure belt is installed correctly to prevent water pump turning in wrong direction. See appropriate article in ENGINE COOLING.
2. To complete installation, reverse removal procedure. Fill with coolant and purge air from cooling system. See «COOLING SYSTEM BLEEDING»(/jeep/grand-cherokee/wj-1998-2004/remont/mechanical/#40l-engine__cooling-system-bleeding) . Remove coolant temperature sensor to bleed air from system while filling.

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. Disconnect oil sensor (if equiped).
2. Position jackstand and a wood block directly under vibration damper. Remove through-bolts from engine mounts. Raise engine enough to remove oil pan. Remove transmission cooler line supports from oil pan, if equipped. Remove oil pan retaining bolts. Remove oil pan by sliding it to rear.

1. Ensure all gasket surfaces are clean. Fabricate 4 alignment dowels from 1/4"-20 x 1 1/2" 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 with enough bolts to hold pan in place. Remove alignment dowels. Install remaining oil pan bolts and tighten to specification. See «TORQUE SPECIFICATIONS»(/jeep/grand-cherokee/wj-1998-2004/remont/mechanical/#40l-engine__torque-specifications) . To complete installation, reverse removal procedure. Fill crankcase. Start engine. Check for leaks.

Description

All vehicles are equipped with a cross flow type radiator with plastic side tanks (Scheme 4)

Plastic tanks, while stronger than brass, are subject to damage by impact, such as from tools or wrenches. Handle radiator with care.

Scheme 4

Do not waste reusable coolant. If the solution is clean, drain the coolant into a clean container for reuse.

Scheme 5

Scheme 6

Scheme 7

Scheme 8

Scheme 9

1. Disconnect the negative battery cable at battery.
2. Drain coolant from radiator.
3. Do not attempt to remove fan/viscous fan drive assembly from vehicle at this time.
4. Remove the front grill.
5. Remove two radiator mounting bolts (Scheme 8)
6. Disconnect both transmission cooler lines from radiator.
7. Disconnect electric fan connector, then disconnect connector harness from shroud (Scheme 8)
8. Disconnect the radiator upper and lower hoses (Scheme 8)
9. Disconnect the overflow hose from radiator (Scheme 8)
10. Remove the air inlet duct at the grill.
11. The lower part of radiator is equipped with two alignment dowel pins (Scheme 9) They are located on the bottom of radiator tank and fit into rubber grommets. These rubber grommets are pressed into the radiator lower crossmember. WARNING: THE AIR CONDITIONING SYSTEM (IF EQUIPPED) IS UNDER A CONSTANT PRESSURE EVEN WITH THE ENGINE OFF. REFER TO REFRIGERANT WARNINGS IN HEATING AND AIR CONDITIONING BEFORE HANDLING ANY AIR CONDITIONING COMPONENT.
12. If equipped with an auxiliary automatic transmission oil cooler, use caution when removing radiator. The oil cooler lines are routed through a rubber air seal on the right side of radiator. Do not cut or tear this seal.
13. Gently lift up and remove radiator from vehicle. Be careful not to scrape the radiator fins against any other component. Also be careful not to disturb the air conditioning condenser (if equipped).

Cleaning

Clean radiator fins With the engine cold, apply cold water and compressed air to the back (engine side) of the radiator to flush the radiator and/or A/C condenser of debris.

The radiator cooling fins should be checked for damage or deterioration. Inspect cooling fins to make sure they are not bent or crushed, these areas result in reduced heat exchange causing the cooling system to operate at higher temperatures. Inspect the plastic end tanks for cracks, damage or leaks.

Inspect the radiator neck for damage or distortion.

1. Equipped with air conditioning: Gently lower the radiator into the vehicle. Guide the two radiator alignment dowels through the holes in the rubber air seals first and then through the A/C support brackets (Scheme 9) Continue to guide the alignment dowels into the rubber grommets located in lower radiator crossmember. The holes in the L-shaped brackets (located on bottom of A/C condenser) must be positioned between bottom of rubber air seals and top of rubber grommets.
2. Connect the radiator upper and lower hoses and hose clamps to radiator (Scheme 8) CAUTION: The tangs on the hose clamps must be positioned straight down.
3. Install coolant reserve/overflow tank hose at radiator (Scheme 8)
4. Connect both transmission cooler lines at the radiator (Scheme 8)
5. Install both radiator mounting bolts (Scheme 8)
6. Install air inlet duct at grill.
7. Attach electric fan harness to shroud, then connect harness to connector (Scheme 8)
8. Install the grill.
9. Install the fan/viscous fan drive assembly to the water pump.
10. Rotate the fan blades (by hand) and check for interference at fan shroud.
11. Be sure of at least 25 mm (1.0 inch) between tips of fan blades and fan shroud.
12. Fill cooling system.
13. Connect battery cable at battery.
14. Start and warm engine. Check for leaks.

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 specification. 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. Seat width runout should not exceed .0025" (.063 mm) after refacing. See CYLINDER HEAD table under ENGINE SPECIFICATIONS.

Valves

Reface valves to specification. After refacing valve, at least .031" (.79 mm) margin must remain. 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.

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 Bore Inspection

1. Using a dial bore gauge, measure each cylinder bore diameter. If a dial bore gauge is not available, DO NOT substitute an inside micrometer. See «PISTON & ROD ASSEMBLY»(/jeep/grand-cherokee/wj-1998-2004/remont/mechanical/#40l-engine__piston-rod-assembly) .
2. Measure cylinder bore at 90 degrees to crankshaft near top of bore. Repeat measurement near middle and bottom of bore. Determine taper by subtracting the smaller diameter from the larger.
3. Rotate bore gauge 90 degrees and repeat measurements. Determine out-of-roundness by comparing difference between each measurement.
4. If cylinder bore taper does not exceed .001" (.025 mm) and out-of-roundness does not exceed .001" (.025 mm), cylinder bore can be honed. If cylinder bore taper or out-of-round exceeds these limits, cylinder must be bored and honed to accept an oversize piston. NOTE: A slight amount of taper always exists in the cylinder bore after an engine has been in use for a period of time.

Piston & Rod Assembly

Scheme 10

1. To correctly select proper size piston, a Cylinder Bore Gauge (6879), capable of reading in .0001" (.003 mm) increments with Gauge Ring (6884) is required. If a suitable dial bore gauge is not available, DO NOT substitute an inside micrometer.
2. Using gauge ring, zero dial bore gauge. Using dial bore gauge, measure cylinder bore and record readings. Measure cylinder bore 3/8" (10 mm) below top of bore in line with axis of crankshaft ("A"). Take a second reading at 90 degrees to first reading ("B"). Perform same measurements at middle of bore, and 3/8" (10 mm) from bottom of bore.
3. Recheck zero of bore gauge in gauge ring. If gauge does not read zero, reset and repeat measurements.
4. Measuring inside diameter of cylinder bore with a .0001" (.003 mm) reading dial bore gauge is mandatory to obtain correct clearance. See «CYLINDER BORE & PISTON IDENTIFICATION»(/jeep/grand-cherokee/wj-1998-2004/remont/mechanical/#40l-engine) table. Piston installation into cylinder bore requires slightly more pressure than for non-coated pistons. Coating will give appearance of a 0-0 fit in cylinder bore.

CYLINDER BORE & PISTON IDENTIFICATION

Fitting Pistons

See PISTON & ROD ASSEMBLY .

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 shiny coating on outer sealing surface. Second ring has slight chamfer on bottom of inside edge. Position ring end gaps in specified area. Ring gaps may vary 20 degrees from positions illustrated. (Scheme 11) See PISTONS, PINS & RINGS table under ENGINE SPECIFICATIONS.

Scheme 11

Rod Bearings

1. Inspect bearings for wear or damage. Replace as necessary. Using Plastigage, check bearing clearance. See «CRANKSHAFT, MAIN & CONNECTING ROD BEARINGS»(/jeep/grand-cherokee/wj-1998-2004/remont/mechanical/#40l-engine) 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»(/jeep/grand-cherokee/wj-1998-2004/remont/mechanical/#40l-engine__torque-specifications) . See «CRANKSHAFT, MAIN & CONNECTING ROD BEARINGS»(/jeep/grand-cherokee/wj-1998-2004/remont/mechanical/#40l-engine) 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»(/jeep/grand-cherokee/wj-1998-2004/remont/mechanical/#40l-engine) 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»(/jeep/grand-cherokee/wj-1998-2004/remont/mechanical/#40l-engine__torque-specifications) . See «CRANKSHAFT, MAIN & CONNECTING ROD BEARINGS»(/jeep/grand-cherokee/wj-1998-2004/remont/mechanical/#40l-engine) 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 90 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»(/jeep/grand-cherokee/wj-1998-2004/remont/mechanical/#40l-engine) table under ENGINE SPECIFICATIONS.

CRANKSHAFT JOURNAL IDENTIFICATION

CONNECTING ROD BEARING INSERT APPLICATION

MAIN BEARING FITTINGS (CRANKSHAFT JOURNALS)

CRANKSHAFT BEARING INSERT APPLICATION

ENGINE LUBRICATION SYSTEM

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 flows from hydraulic valve lifters through push rods to rocker arms. (Scheme 12)

Crankcase Capacity

Oil capacity is 6.0 qts. (5.7L) with filter change.

Oil Pressure

Minimum oil pressure should be 13 psi (.9 kg/cm 2 ) at 600 RPM. Normal oil pressure should be 37-75 psi (3-5 kg/cm 2 ) at greater than 1600 RPM. Oil pressure relief is 75 psi (5 kg/cm 2 ).

Scheme 12

Drain engine oil. Remove oil pan. See OIL PAN . 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. To install, install NEW gasket and oil pump. Tighten retaining bolts to specification. See TORQUE SPECIFICATIONS .

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

GENERAL SPECIFICATIONS

GENERAL SPECIFICATIONS

CRANKSHAFT, MAIN BEARINGS & CONNECTING ROD BEARINGS SPECIFICATIONS

CRANKSHAFT, MAIN & CONNECTING ROD BEARINGS

CONNECTING RODS SPECIFICATIONS

CONNECTING RODS

PISTONS, PISTON PINS & PISTON RINGS SPECIFICATIONS

PISTONS, PINS & RINGS

CYLINDER HEAD SPECIFICATIONS

CYLINDER HEAD

CAMSHAFT SPECIFICATIONS

CAMSHAFT

VALVE LIFTERS SPECIFICATIONS

VALVE LIFTERS

CYLINDER BLOCK SPECIFICATIONS

CYLINDER BLOCK

ENGINE VALVES & VALVE SPRINGS SPECIFICATIONS

VALVES & VALVE SPRINGS

See also:
• ENGINE IDENTIFICATION CODE
• FUEL PRESSURE RELEASE
• THROTTLE CABLE ADJUSTMENT
• POWER STEERING BLEEDING
• TORQUE SPECIFICATIONS
• ROCKER ARMS
• COOLING SYSTEM BLEEDING
• CRANKSHAFT & MAIN BEARINGS
• PISTON & ROD ASSEMBLY