4.0l Engine - VIN [s] Jeep Grand Cherokee ZJ рестайлинг

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.

SERPENTINE BELT ROUTING

Note. For belt adjustment information, see BELT ADJUSTMENT in COOLING SYSTEM SPECIFICATIONS article.

Note. Use illustration to ensure serpentine belt is correctly routed. (Scheme 19)or (Scheme 20).

Scheme 19

Scheme 20

TROUBLE SHOOTING

Note. To trouble shoot mechanical engine components, see ENGINE MECHANICAL in BASIC 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

With Test Port

1. Disconnect negative battery cable. Remove fuel filler cap. Remove cap from pressure test port on fuel rail. (Scheme 21) Place shop towels around pressure test port to absorb spilled fuel.
2. Connect Fuel Pressure Gauge Tool (5069). Place gauge end of hose into an approved gasoline container. Release fuel pressure. Remove shop towels and dispose of properly. Install pressure test port cap.

Without Test Port

1. 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 then 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 two-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 towards 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.

Scheme 21

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 above procedure until fluid level remains constant after running engine.
2. Raise and support front wheels. Slowly turn steering wheel fight 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.

Note. On models with 4.0 L engine, front grill must be removed to access radiator draincock. Draining cooling system can be accomplished by removing drain plug from side of block as well as by loosening radiator draincock. Drain plug is located on lower left side of engine block. (Scheme 22)

Scheme 22

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/zj-1996-1998/remont/mechanical/#40l-engine-vin-s__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. 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 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. 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. See «THROTTLE CABLE ADJUSTMENT»(/jeep/grand-cherokee/zj-1996-1998/remont/mechanical/#40l-engine-vin-s__throttle-cable-adjustment) under ADJUSTMENTS. Bleed power steering system. See «POWER STEERING BLEEDING»(/jeep/grand-cherokee/zj-1996-1998/remont/mechanical/#40l-engine-vin-s__power-steering-bleeding) . Tighten bolts to specification. See «TORQUE SPECIFICATIONS»(/jeep/grand-cherokee/zj-1996-1998/remont/mechanical/#40l-engine-vin-s) table. Check fluid levels, and refill if necessary.

Removal - Engine Mounts

1. Disconnect negative cable from battery. Raise the vehicle. Support the engine.
2. Remove the nut from the through bolt. DO NOT remove the through bolt. (Scheme 23)
3. Remove the retaining bolts and nuts from the support cushions.
4. Remove the through bolt. Remove the support cushions from the support cushion brackets. (Scheme 24)

Installation - Engine Mounts

1. If the engine support bracket was removed, position the bracket onto the block and install the attaching bolts. Tighten the engine support bracket bolts to 45 ft. lbs. (61 N.m).
2. If the support cushion bracket was removed, position the bracket onto the lower front sill. Install support cushion bracket bolts and nuts. Tighten the bolts to 40 ft. lbs. (54 N.m). Tighten the nuts to 30 ft. lbs. (41 N.m).
3. Place the support cushion into position on the support cushion bracket. Install and tighten the bolts and nuts to 30 ft. lbs. (41 N.m).
4. Install the through bolt and the retaining nut. Tighten the through bolt nut to 48 ft. lbs. (65 N.m).
5. Remove the engine support.
6. Lower the vehicle.
7. Connect negative cable to battery.

Scheme 23

Scheme 24

Removal - Transmission Mounts

1. Disconnect negative cable from battery. Raise the vehicle and support the transmission. Remove the nuts holding the support cushion to the crossmember. Remove the crossmember. For manual transmission, go to next step. For automatic transmission, go to step 3.
2. On manual transmission, remove the support cushion nuts and remove the cushion. (Scheme 26) Remove the transmission support bracket bolts and remove the bracket from the transmission.
3. On automatic transmission, remove the support cushion bolts and remove the cushion and the support bracket from the transmission (4WD) or from the adaptor bracket (2WD). (Scheme 25) On 2WD vehicles, remove the bolts holding the transmission support adaptor bracket to the transmission. Remove the adaptor bracket.

Installation - Transmission Mounts

1. For automatic transmission, go to 3 . For manual transmission, install the transmission support bracket to the transmission. Install the bolts and tighten to 34 ft. lbs. (46 N.m).
2. Install the support cushion to the support bracket. Install the nuts and tighten to 55 ft. lbs. (75 N.m). Go to step 4 .
3. On automatic transmission with 2WD, position the transmission support adaptor bracket to the transmission. Install the bolts and tighten to 55 ft. lbs. (75 N.m). On all models, position the transmission support bracket and support cushion to the adaptor bracket (2WD) or the transmission (4WD). Install the bolts and tighten to 55 ft. lbs. (75 N.m).
4. Position the crossmember onto the support cushion studs. Install the stud nuts and tighten to 192 INCH lbs. (22 N.m). Install crossmember-to-sill bolts and tighten to 30 ft. lbs. (41 N.m). Remove the transmission support. Lower the vehicle. Connect negative cable to battery.

Scheme 25

Scheme 26

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/zj-1996-1998/remont/mechanical/#40l-engine-vin-s__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 27) See «TORQUE SPECIFICATIONS»(/jeep/grand-cherokee/zj-1996-1998/remont/mechanical/#40l-engine-vin-s) table. Reverse removal procedure to complete installation.

Scheme 27

Remove exhaust manifold with intake manifold. See INTAKE MANIFOLD .

CYLINDER HEAD

Note. On models with 4.0 L engine, front grill must be removed to access radiator draincock. Draining cooling system can be accomplished by removing drain plug from side of block as well as by loosening radiator draincock. Drain plug is located on lower left side of engine block. (Scheme 22)

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/zj-1996-1998/remont/mechanical/#40l-engine-vin-s__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»(/jeep/grand-cherokee/zj-1996-1998/remont/mechanical/#40l-engine-vin-s) and «EXHAUST MANIFOLD»(/jeep/grand-cherokee/zj-1996-1998/remont/mechanical/#40l-engine-vin-s) . 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 it 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/zj-1996-1998/remont/mechanical/#40l-engine-vin-s) 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 28) See «TORQUE SPECIFICATIONS»(/jeep/grand-cherokee/zj-1996-1998/remont/mechanical/#40l-engine-vin-s) table.
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/zj-1996-1998/remont/mechanical/#40l-engine-vin-s__cooling-system-bleeding). Start engine, and check for leaks.

Scheme 28

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.

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 (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 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 29) Remove preload bolt. Remove timing chain and sprockets as an assembly.

Scheme 29

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 preload bolt and washer. Tighten to specification. See «TORQUE SPECIFICATIONS»(/jeep/grand-cherokee/zj-1996-1998/remont/mechanical/#40l-engine-vin-s) table.
2. Verify proper installation by rotating crankshaft until timing mark on camshaft is at approximately one o'clock position. (Scheme 30) Timing sprockets are installed correctly if 15 timing chain pins are between timing marks on both sprockets.
3. On all engines, 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/zj-1996-1998/remont/mechanical/#40l-engine-vin-s) table.

Scheme 30

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/zj-1996-1998/remont/mechanical/#40l-engine-vin-s) table.
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.

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/zj-1996-1998/remont/mechanical/#40l-engine-vin-s__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»(/jeep/grand-cherokee/zj-1996-1998/remont/mechanical/#40l-engine-vin-s) . 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 (1600 km). Refill cooling system. Adjust ignition timing. Check for leaks.

Remove transmission inspection cover. Remove oil pan. See OIL PAN . Remove rear main bearing cap (No. 7), and push upper seal from groove. Ensure crankshaft is 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/zj-1996-1998/remont/mechanical/#40l-engine-vin-s__crankshaft-main-bearings) under CYLINDER BLOCK ASSEMBLY under OVERHAUL. To install remaining components, reverse removal procedure.

RADIATOR

1. Disconnect battery negative cable.
2. Observe the previous WARNING.
3. Remove radiator pressure cap.
4. For access to radiator draincock, remove radiator grill mounting screws and remove grill.
5. Attach one end of a 24 inch long X 1/4 inch ID hose to the radiator petcock. Put the other end into a clean container. Open petcock and drain radiator.
6. Disconnect electric cooling fan electrical connector, if equipped.
7. If equipped, remove two electric cooling fan mounting bolts. Lift cooling fan straight up until alignment tabs at the bottom are clear of slots in bracket at bottom of radiator.
8. Remove the two mechanical (non-electrical) fan shroud mounting bolts. Lift shroud straight up until alignment tabs at the bottom are clear of slots in bracket at bottom of radiator. Place shroud over mechanical fan.
9. If equipped, disconnect and plug automatic transmission fluid cooler lines. Quick Connect Fitting Release Tool 6935 may be needed. If equipped with remote transmission cooler, remove line to cooler from bracket at bottom of radiator.
10. Disconnect radiator upper and lower hoses clamps. Disconnect radiator upper and lower hoses.
11. Mark the position of the hood latch striker on the radiator crossmember and remove hood latch striker.
12. Remove two radiator upper crossmember to isolator nuts. (Scheme 31)
13. Remove four radiator upper crossmember bolts and remove upper crossmember.
14. If equipped with air conditioning, separate radiator from condenser by removing condenser-to-radiator mounting brackets.
15. Lift radiator straight up and out of engine compartment taking care not to damage fins.

Scheme 31

1. Lower radiator into engine compartment. Position alignment dowels into rubber grommets in radiator lower crossmember.
2. If equipped with air conditioning, attach condenser to radiator with mounting brackets.
3. Install radiator upper crossmember and 4 mounting bolts.
4. Install radiator upper crossmember-to-isolator nuts. Tighten nuts to 86 INCH lbs. (10 N.m). If isolator-to-radiator nuts had been removed, tighten them to 47 INCH lbs. (5 N.m).
5. Install hood latch striker. Note previously marked position.
6. Connect radiator upper and lower hoses.
7. If equipped, connect automatic transmission fluid cooler lines. If equipped with remote cooler, attach cooler line to bracket at bottom of radiator.
8. Install electric cooling fan (if equipped). Insert alignment tabs at bottom of fan shroud into slots in bracket at bottom of radiator. Tighten mounting bolts to 31 INCH lbs. (3 N.m).
9. Connect electric cooling fan electrical connector.
10. Install mechanical cooling fan shroud. Insert alignment tabs at bottom of shroud into slots in bracket at bottom of radiator. Tighten mounting bolts to 31 INCH lbs. (3 N.m).
11. Close radiator draincock.
12. Install grille.
13. Connect negative battery cable.
14. Fill cooling system with correct coolant.
15. Install pressure cap.
16. Check and adjust automatic transmission fluid level (if equipped).

WATER PUMP

Note. On models with 4.0 L engine, front grill must be removed to access radiator draincock. Draining cooling system can be accomplished by removing drain plug from side of block as well as by loosening radiator draincock. Drain plug is located on lower left side of engine block. (Scheme 22)

1. Disconnect negative battery cable. Drain cooling system. Disconnect electric cooling fan connector. Remove electric cooling fan and electric fan shroud assembly (if equipped).
2. Loosen, but do not remove, 4 water pump pulley-to-water pump hub bolts and 4 viscous fan-to-idler pulley nuts. Remove accessory drive belt. Remove 4 viscous fan to idler pulley nuts, and remove fan and shroud together.
3. Remove 4 water pump pulley bolts and remove pulley. Remove power steering pump and bracket. Disconnect heater hoses and lower radiator hose at water pump. Remove 4 water pump retaining bolts. Remove water pump.

1. Clean all gasket surfaces. Install water pump. Tighten bolts to specification. See «TORQUE SPECIFICATIONS»(/jeep/grand-cherokee/zj-1996-1998/remont/mechanical/#40l-engine-vin-s) table. Ensure pump turns freely. Ensure belt is installed correctly to prevent water pump turning in wrong direction. See «SERPENTINE BELT ROUTING»(/jeep/grand-cherokee/zj-1996-1998/remont/mechanical/#40l-engine-vin-s__serpentine-belt-routing) under ADJUSTMENTS.
2. To complete installation, reverse removal procedure. Fill with coolant and purge air from cooling system. See «COOLING SYSTEM BLEEDING»(/jeep/grand-cherokee/zj-1996-1998/remont/mechanical/#40l-engine-vin-s__cooling-system-bleeding) . Remove coolant temperature sensor to bleed air from system while filling.

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

1. Drain the coolant from the radiator until the level is below the thermostat housing.
2. Remove radiator upper hose and heater hose at thermostat.
3. Disconnect wiring connector at engine coolant temperature sensor.
4. Remove thermostat housing mounting bolts, thermostat housing, gasket and thermostat. (Scheme 32)
5. Remove and discard old gasket.

Scheme 32

1. Clean the gasket mating surfaces.
2. Install the replacement thermostat so that the pellet, which is encircled by a coil spring, faces the engine. All thermostats are marked on the outer flange to indicate the proper installed position.
3. Observe the recess groove in the engine cylinder head. (Scheme 33) Position thermostat into this groove with arrow and air bleed hole on outer flange pointing up.
4. Install replacement gasket and thermostat housing. (Scheme 32)
5. Tighten the housing bolts. See «TORQUE SPECIFICATIONS»(/jeep/grand-cherokee/zj-1996-1998/remont/mechanical/#40l-engine-vin-s__torque-specifications).
6. Install hoses to thermostat housing.
7. Install electrical connector to coolant temperature sensor.
8. Be sure that the radiator draincock is tightly closed. Fill the cooling system to the correct level with the required coolant mixture.
9. Start and warm the engine. Check for leaks.

Scheme 33

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 and a wood block directly under vibration damper. 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.

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/zj-1996-1998/remont/mechanical/#40l-engine-vin-s) table. To complete installation, reverse removal procedure. Fill crankcase. Start 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 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. (Scheme 34) 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.

Scheme 34

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/zj-1996-1998/remont/mechanical/#40l-engine-vin-s__piston-rod-assembly).
2. Measure cylinder bore at 90 degrees to crankshaft near top of bore. Repeat measurement near bottom of bore. Determine taper by subtracting the smaller diameter from the larger. (Scheme 35)
3. Rotate bore gauge 120 degrees and repeat measurements. Rotate bore gauge another 120 degrees and repeat measurements again. Determine out-of-roundness by comparing the difference between each 120-degree measurement.
4. If cylinder bore taper does not exceed.001" (.025 mm) and out-of-roundness does not exceed.001" (.025 mm), the 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

DO NOT substitute old style pistons for the new coated pistons. The new coated pistons are supplied pre-assembled with piston, piston pin and connecting rod as a unit and must be replaced as a complete set. The new coated piston/connecting rod assembly can be used to service older engines but must be replaced as complete sets.

Scheme 35

1. To correctly select proper size piston, a Cylinder Bore Gauge (6879), capable of reading in.0001" 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 2 5/16" (58.725 mm) below top of bore in line with axis of crankshaft ("A"). Take a second reading at 90 degrees to first reading ("B"). (Scheme 35)
3. Recheck zero of bore gauge in gauge ring. If gauge does not read zero, reset and repeat measurements.
4. Measuring the inside diameter of the cylinder bore with a.0001" reading dial bore gauge is MANDATORY to obtain correct clearance. See «CYLINDER BORE & PISTON IDENTIFICATION»(/jeep/grand-cherokee/zj-1996-1998/remont/mechanical/#40l-engine-vin-s) table. Piston installation into cylinder bore requires slightly more pressure than for non-coated pistons. The coating will give the appearance of a 0-0 fit in the 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 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. (Scheme 36) See PISTONS, PINS & RINGS table under ENGINE SPECIFICATIONS.

Scheme 36

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/zj-1996-1998/remont/mechanical/#40l-engine-vin-s) 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/zj-1996-1998/remont/mechanical/#40l-engine-vin-s) table. See «CRANKSHAFT, MAIN & CONNECTING ROD BEARINGS»(/jeep/grand-cherokee/zj-1996-1998/remont/mechanical/#40l-engine-vin-s) 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/zj-1996-1998/remont/mechanical/#40l-engine-vin-s) 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/zj-1996-1998/remont/mechanical/#40l-engine-vin-s) table. See «CRANKSHAFT, MAIN & CONNECTING ROD BEARINGS»(/jeep/grand-cherokee/zj-1996-1998/remont/mechanical/#40l-engine-vin-s) 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»(/jeep/grand-cherokee/zj-1996-1998/remont/mechanical/#40l-engine-vin-s) 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 37)

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 (255-517 kPa) above 1600 RPM. Oil pressure relief is 75 psi (517 kPa).

Scheme 37

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.

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

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»(/jeep/grand-cherokee/zj-1996-1998/remont/mechanical/#40l-engine-vin-s) table.

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 OVERHAUL PROCEDURES
• BELT ADJUSTMENT
• ENGINE MECHANICAL
• ENGINE IDENTIFICATION CODE
• FUEL PRESSURE RELEASE
• THROTTLE CABLE ADJUSTMENT
• POWER STEERING BLEEDING
• ROCKER ARMS
• COOLING SYSTEM BLEEDING
• CYLINDER HEAD
• CRANKSHAFT & MAIN BEARINGS
• SERPENTINE BELT ROUTING
• TORQUE SPECIFICATIONS
• PISTON & ROD ASSEMBLY