Exhaust System and Intake Manifold — 1996 Jeep Grand Cherokee ZJ Service Manual

Pages 1044–1053 · 10 pages · 0 words repaired

CATALYTIC CONVERTER

The stainless steel catalytic converter body is designed to last the life of the vehicle. Excessive heat can result in bulging or other distortion, but excessive heat will not be the fault of the converter. If unburned fuel enters the converter, overheating may occur. If a converter is heat-damaged, correct the cause of the damage at the same time the converter is replaced. Also, inspect all other components of the exhaust system for heat damage.

Unleaded gasoline must be used to avoid contaminating the catalyst core.

DO NOT remove spark plug wires from plugs or by any other means short out cylinders. Failure of the catalytic converter can occur due to a temperature increase caused by unburned fuel passing through the converter.

DO NOT allow the engine to operate at fast idle for extended periods (over 5 minutes). This condition may result in excessive temperatures in the exhaust system and on the floor pan.

HEAT SHIELDS

Heat shields are needed to protect both the vehicle and the environment from the high temperatures developed by the catalytic converter (Fig. 3) (Fig. 4). The catalytic converter releases additional heat into the exhaust system. Under severe operating conditions, the temperature increases in the area of the converter. Such conditions can exist when the engine misfires or otherwise does not operate at peak efficiency.

BAND CLAMP (TORCA)

Taking the place of the exhaust clamps will be a new style band clamp (Torca) this will be used on all exhaust system (Fig. 5).

DIAGNOSIS AND TESTING

EXHAUST SYSTEM DIAGNOSIS

|
EXCESSIVE EXHAUST NOISE 1. Leaks at pipe joints. 1. Tighten clamps at leaking joints.
2. Burned or blown-out muffler. 2. Replace muffler assembly. Check
exhaust system.
3. Burned or rusted-out exhaust pipe. 3. Replace exhaust pipe.
4. Exhaust pipe leaking at manifold flange. | 4. Tighten connection attaching nuts.
5. Exhaust manifold cracked or broken. 5. Replace exhaust manifold.
6. Leak between exhaust manifold and 6. Tighten exhaust manifold to cylinder
cylinder head. head stud nuts or bolts.
7. Restriction in muffler or tail pipe. 7. Remove restriction, if possible. Replace
muffler or tail pipe, as necessary.
LEAKING EXHAUST GASES 1. Leaks at pipe joints. 1. Tighten clamps at leaking joints.
2. Damaged or improperly installed gaskets. | 2. Replace gaskets, as necessary.
J9311-9

REMOVAL AND INSTALLATION

EXHAUST PIPE—4.0/5.2L ENGINES

REMOVAL

WARNING: IF TORCHES ARE USED WHEN WORK- ING ON THE EXHAUST SYSTEM, DO NOT ALLOW THE FLAME NEAR THE FUEL LINES.

(1) Raise and support the vehicle. (2) Saturate the bolts and nuts with heat valve lubricant. Allow 5 minutes for penetration.

(3) Remove the oxygen sensor from the exhaust pipe (Fig. 6) (Fig. 7).

(4) Disconnect the exhaust pipe from the engine exhaust manifold. On 4.0L engines, discard the exhaust manifold seal (Fig. 6).

(a) Heat the exhaust pipe and catalytic converter connection with an torch until the metal becomes cherry red.

(b) While the metal is still cherry red, twist the exhaust pipe back and forth to separate it from the catalytic converter. (5) Remove the Torca clamp from the exhaust pipe and catalytic converter connection (Fig. 6) (Fig. 7). Disconnect the exhaust pipe from the catalytic converter. If needed:

(6) Disconnect the exhaust pipe hanger from the rear mount bracket insulator (Fig. 8).

(7) Remove the exhaust pipe.

INSTALLATION

(1) Position the exhaust pipe onto the catalytic converter.

(2) Connect the exhaust pipe hanger to the rear mount bracket insulator.

(3) On 4.0L engines, install a new seal between the exhaust pipe and the engine exhaust manifold (Fig. 6). Connect the exhaust pipe to the engine exhaust manifold. Tighten the nuts to 31 N·m (23 ft. lbs.) torque.

(4) Position the Torca clamp over the exhaust pipe/ catalytic converter connection (Fig. 6) (Fig. 7). Tighten the nuts to 75 N·m (55 ft. lbs.) torque.

(5) Coat the oxygen sensor with anti-seize compound. Install the sensor and tighten the nut to 48 N·m (35 ft. lbs.) torque.

(6) Lower the vehicle. (7) Start the engine and inspect for exhaust leaks and exhaust system contact with the body panels. Adjust the alignment, if needed.

(8) After initial start-up, check the engine exhaust manifold to exhaust pipe nuts for proper torque.

CATALYTIC CONVERTER—4.0/5.2L ENGINES

REMOVAL

WARNING: IF TORCHES ARE USED WHEN WORK- ING ON THE EXHAUST SYSTEM, DO NOT ALLOW THE FLAME NEAR THE FUEL LINES.

(1) Raise and support the vehicle. (2) Saturate the bolts and nuts with heat valve lubricant. Allow 5 minutes for penetration.

(3) Remove Torca clamp from the catalytic converter and exhaust pipe connection (Fig. 9).

(4) Remove Torca clamp from the catalytic converter and muffler connection (Fig. 9).

(5) Disconnect oxygen sensor wiring. (6) Heat the exhaust pipe, catalytic converter and muffler connections with an torch until the metal becomes cherry red.

(7) While the metal is still cherry red, twist the catalytic converter back and forth to separate it from the exhaust pipe and the muffler.

INSTALLATION

(1) Position the Torca clamp over the exhaust pipe/ catalytic converter connection (Fig. 9). Tighten the nuts to 71 N·m (52 ft. lbs.) torque.

Connection

(2) Install the muffler onto the catalytic converter until the alignment tab is inserted into the alignment slot.

(3) Install the Torca clamp at the muffler and catalytic converter connection (Fig. 9). Tighten the clamp nuts to 71 N·m (52 ft. lbs.) torque.

(4) Connect oxygen sensor wiring. (5) Lower the vehicle. (6) Start the engine and inspect for exhaust leaks and exhaust system contact with the body panels. Adjust the alignment, if needed.

MUFFLER AND TAILPIPE—4.0/5.2L ENGINES

REMOVAL

All original equipment exhaust systems are manufactured with the tailpipe welded to the muffler. Service replacement mufflers and tailpipes are either clamped together or welded together.

WARNING: IF TORCHES ARE USED WHEN WORK- ING ON THE EXHAUST SYSTEM, DO NOT ALLOW THE FLAME NEAR THE FUEL LINES.

(1) Raise and support the vehicle. (2) Saturate the bolts and nuts with heat valve lubricant. Allow 5 minutes for penetration.

(3) Remove the Torca clamp from the catalytic converter and muffler connection (Fig. 9).

(4) Heat the catalytic converter-to-muffler connection with an torch until the metal becomes cherry red.

(5) While the metal is still cherry red, remove the tailpipe/muffler assembly from the catalytic converter.

(6) Remove the tailpipe from the tailpipe hanger (Fig. 10).

(7) Remove the tailpipe/muffler assembly.

INSTALLATION

(1) If the tailpipe hanger assembly was removed, install the hanger to the frame. Tighten the bolts to 22 N·m (192 in. lbs.) torque. (2) Position the tailpipe and muffler onto the tailpipe hanger (Fig. 10).

(3) Install the muffler onto the catalytic converter. Make sure that the tailpipe has sufficient clearance from the floor pan. Install Torca clamp and tighten the nuts to 75 N·m (55 ft. lbs.) torque.

(4) Lower the vehicle. (5) Start the engine and inspect for exhaust leaks and exhaust system contact with the body panels. Adjust the alignment, if needed.

INTAKE AND EXHAUST MANIFOLD—4.0L ENGINE

REMOVAL

NOTE: THE ENGINE INTAKE AND EXHAUST MANI- FOLD MUST BE REMOVED AND INSTALLED TOGETHER. THE MANIFOLDS USE A COMMON GASKET AT THE CYLINDER HEAD.

(1) Disconnect the negative cable from the battery. (2) Remove air cleaner inlet hose from throttle plate assembly.

(3) Remove the air cleaner assembly. (4) Remove the throttle cable, vehicle speed control cable (if equipped) and the transmission line pressure cable.

(5) Disconnect all electrical connectors on the intake manifold.

(6) Disconnect and remove the fuel system supply and return lines from the fuel rail assembly (refer to Group 14, Fuel System).

(7) Loosen the accessory drive belt (refer to Group 7, Cooling System). Loosen the tensioner. (8) Remove the power steering pump and bracket from the intake manifold and set aside.

(9) Remove the fuel rail and injectors (refer to Group 14, Fuel System).

(10) Raise the vehicle. (11) Disconnect the exhaust pipe from the engine exhaust manifold. Discard the seal.

(12) Lower the vehicle. (13) Remove the intake manifold and engine exhaust manifold.

INSTALLATION

If the manifold is being replaced, ensure all the fitting, etc. are transferred to the replacement manifold.

(1) Install a new engine exhaust/intake manifold gasket over the alignment dowels on the cylinder head.

(2) Position the engine exhaust manifold to the cylinder head. Install fastener Number 3 and finger tighten at this time (Fig. 11).

(3) Install intake manifold on the cylinder head dowels.

(4) Install washer and fastener Numbers 1, 2, 4, 5, 8, 9, 10 and 11 (Fig. 11). (5) Install washer and fastener Numbers 6 and 7 (Fig. 11).

(6) Tighten the fasteners in sequence and to the specified torque (Fig. 11).

• Fastener Numbers 1 through 5—Tighten to 33 N·m (24 ft. lbs.) torque.

• Fastener Numbers 6 and 7—Tighten to 31 N·m (23 ft. lbs.) torque.

• Fastener Numbers 8 through 11—Tighten to 33 N·m (24 ft. lbs.) torque.

(7) Install the fuel rail and injectors (refer to Group 14, Fuel System).

(8) Install the power steering pump and bracket to the intake manifold. Tighten the belt to specification (refer to Group 7, Cooling System for the proper procedures).

(9) Install the fuel system supply and return lines to the fuel rail assembly. Before connecting the fuel system lines to the fuel rail replace the O-rings in the quick-connect fuel line couplings. Refer to Group 14, Fuel System for the proper procedure.

(10) Connect all electrical connections on the intake manifold.

(11) Connect the vacuum connector on the intake manifold and install it in the bracket.

(12) Install throttle cable, vehicle speed control cable (if equipped).

(13) Install the transmission line pressure cable (if equipped). Refer to Group 21, Transmission for the adjustment procedures.

(14) Install air cleaner assembly. (15) Connect air inlet hose to the throttle plate assembly.

(16) Raise the vehicle on a side mounted hoist. (17) Use a new engine exhaust manifold seal. Connect the exhaust pipe to the engine exhaust manifold.

(18) Lower the vehicle. (19) Connect the negative cable to the battery. (20) Start the engine and check for leaks.

INTAKE MANIFOLD—5.2L ENGINE

REMOVAL

The aluminum intake manifold is a single plane design with equal length runners. The manifold is sealed by flange side gaskets with front and rear cross-over gaskets. The intake manifold has internal EGR.

(1) Disconnect the negative cable from the battery. (2) Drain the cooling system (refer to Group 7, Cooling System for the proper procedures).

(3) Remove the generator (refer to Group 8B Battery/Starting/Charging Systems).

(4) Remove the air cleaner. (5) Remove the fuel lines and fuel rail (refer to Group 14, Fuel System).

(6) Disconnect the accelerator linkage and, if so equipped, the speed control and transmission kickdown cables.

(7) Remove the return spring. (8) Remove the distributor cap and wires. (9) Disconnect the coil wires. (10) Disconnect the heat indicator sending unit wire.

(11) Disconnect the heater hoses and bypass hose. (12) Remove the closed crankcase ventilation and evaporation control systems.

(13) Remove the A/C compressor bolts and set the compressor on the fan shroud.

(14) Remove the support bracket from the intake manifold and the mounting bracket.

(15) Remove intake manifold bolts. (16) Lift the intake manifold and throttle body out of the engine compartment as an assembly.

(17) Remove and discard the flange side gaskets and the front and rear cross-over gaskets.

(18) Remove the throttle body bolts and lift the throttle body off the intake manifold. Discard the throttle body gasket.

(19) Remove the plenum pan as follows:

(a) Turn the intake manifold upside down. Support the manifold.

(b) Remove the bolts and lift the pan off the manifold. Discard the gasket.

INSTALLATION

(1) Install the plenum pan, if removed, as follows:

(a) Turn the intake manifold upside down. Support the manifold.

(b) Place a new plenum pan gasket onto the seal rail of the intake manifold. Position the pan over the gasket. Align all the gasket and pan holes with the intake manifold.

(c) Hand start all bolts. (d) Tighten the bolts, in sequence (Fig. 12), as follows:

• Step 1—Tighten bolts to 2.7 N·m (24 in. lbs.) torque.

• Step 2—Tighten bolts to 5.4 N·m (48 in. lbs.) torque.

• Step 3—Tighten bolts to 9.5 N·m (84 in. lbs.) torque.

• Step 4—Check that all bolts are tighten to 9.5 N·m (84 in. lbs.) torque.

(2) Using a new gasket, install the throttle body onto the intake manifold. Tighten the bolts to 23 N·m (200 in. lbs.) torque.

(3) Place the 4 plastic locator dowels into the holes in the block (Fig. 13).

(4) Apply Mopart Silicone Rubber Adhesive Sealant, or equivalent, to the four corner joints. An excessive amount of sealant is not required to ensure a leak proof seal. However, an excessive amount of sealant may reduce the effectiveness of the flange gasket. The sealant should be slightly higher than the cross-over gaskets, approximately 5 mm (0.2 in).

(5) Install the front and rear cross-over gaskets onto the dowels (Fig. 13).

(6) Install the flange gaskets. Ensure that the vertical port alignment tab is resting on the deck face of the block. Also the horizontal alignment tabs must be in position with the mating cylinder head gasket tabs (Fig. 14). The words MANIFOLD SIDE should be visible on the center of each flange gasket.

(7) Carefully lower intake manifold into position on the cylinder block and cylinder heads. Use the alignment dowels in the cross-over gaskets to position the intake manifold. After intake manifold is in place, inspect to make sure seals are in place.

(8) The following torque sequence duplicates the expected results of the automated assembly system (Fig. 15).

• Step 1—Tighten bolts 1 through 4, in sequence, to 8 N·m (72 in. lbs.) torque. Tighten in alternating steps 1.4 N·m (12 in. lbs.) torque at a time.

• Step 2—Tighten bolts 5 through 12, in sequence, to 8 N·m (72 in. lbs.) torque.

• Step 3—Check that all bolts are tighten to 8 N·m (72 in. lbs.) torque.

• Step 4—Tighten all bolts, in sequence, to 16 N·m (12 ft. lbs.) torque.

• Step 5—Check that all bolts are tighten to 16 N·m (12 ft. lbs.) torque.

(9) Install closed crankcase ventilation and evaporation control systems.

(10) Install the coil wires. (11) Connect the heat indicator sending unit wire.

(12) Connect the heater hoses and bypass hose. (13) Install distributor cap and wires. (14) Hook up the return spring. (15) Connect the accelerator linkage and, if so equipped, the speed control and transmission kickdown cables.

(16) Install the fuel lines and fuel rail (refer to Group 14, Fuel System).

(17) Install the support bracket to the intake manifold and the mounting bracket.

(18) Install the generator and drive belt. Tighten generator mounting bolt to 41 N·m (30 ft. lbs.) torque. Tighten the adjusting strap bolt to 23 N·m (200 in. lbs.) torque. Refer to Group 7, Cooling System for the proper adjusting of belt tension.

(19) Install the A/C compressor on the mounting bracket (refer to Group 24, Heating and Air Conditioning).

(20) Install the air cleaner. (21) Fill cooling system (refer to Group 7, Cooling System for the proper procedure).

(22) Connect the negative cable to the battery.

EXHAUST MANIFOLD—5.2L ENGINE

REMOVAL

Exhaust manifolds are LOG type with balanced flow.

(1) Disconnect the negative cable from the battery. (2) Remove the exhaust manifold heat shields (Fig. 16).

Shown)

(3) Remove the ERG tube (refer to Group 25, Emission Control Systems).

(4) Raise the vehicle. (5) Remove the bolts and nuts attaching the exhaust pipe to the exhaust manifold.

(6) Lower the vehicle. (7) Remove bolts, nuts and washers attaching manifold to cylinder head.

(8) Remove manifold from the cylinder head.

INSTALLATION

CAUTION: If the studs came out with the nuts when removing the exhaust manifold, install new studs.

(1) Position the exhaust manifolds on the two studs located on the cylinder head. Install conical washers and nuts on these studs (Fig. 17).

(2) Install new bolt and washer assemblies in the remaining holes (Fig. 17). Start at the center arm and work outward. Tighten the bolts and nuts to 27 N·m (20 ft. lbs.) torque.

(3) Raise the vehicle. (4) Assemble the exhaust pipe to the exhaust manifold and secure with bolts, nuts and washers. Tighten these nuts to 31 N·m (23 ft. lbs.) torque.

(5) Lower the vehicle. (6) Install the EGR tube (refer to Group 25, Emission Control Systems).

CAUTION: The exhaust manifold heat shields MUST be installed to protect the underhood components.

(7) Install the exhaust manifold heat shields. Tighten the nuts to 27 N·m (20 ft. lbs.) torque.

(8) Connect the negative cable to the battery.

CLEANING AND INSPECTION

INTAKE AND EXHAUST MANIFOLD—4.0L ENGINE

Clean the mating surfaces of the cylinder head and the manifold if the original manifold is to be installed.

INTAKE MANIFOLD— 5.2L ENGINE

CLEANING

Clean manifold in solvent and blow dry with compressed air.

Clean cylinder block front and rear gasket surfaces using a suitable solvent.

The plenum pan rail must be clean and dry (free of all foreign material).

INSPECTION

Inspect manifold for cracks. Inspect mating surfaces of manifold for flatness with a straightedge.

EXHAUST MANIFOLD—5.2L ENGINE

CLEANING

Clean mating surfaces on cylinder head and manifold, wash with solvent and blow dry with compressed air. Inspect manifold for cracks.

INSPECTION

Inspect mating surfaces of manifold for flatness with a straight edge. Seal surfaces must be flat within 0.1 mm (0.004 inch) overall.

SPECIFICATIONS

TORQUE

DESCRIPTION TORQUE Adjusting Strap

Bolts . . . . . . . . . . . . . . . . . . . .23 N·m (200 in. lbs.) Catalytic Converter-to-Exhaust Pipe

Band Clamp (Torca). . . . . . . . . .71 N·m (52 ft. lbs.) Exhaust Pipe-to-Manifold

Nuts . . . . . . . . . . . . . . . . . . . . .31 N·m (23 ft. lbs.) Exhaust and Intake Manifold

Bolts#1–5 & #8–11 (4.0L) . . . . . 33 N·m (24 ft. lbs.) Exhaust Manifold Heat Shield

Nuts (5.2L) . . . . . . . . . . . . . . . .27 N·m (20 ft. lbs.) Exhaust Manifold

Nuts #6 & 7 (4.0L) . . . . . . . . . .31 N·m (23 ft. lbs.) Exhaust Manifold

Nuts/Bolts (5.2L) . . . . . . . . . . . .27 N·m (20 ft. lbs.) Floor Pan Heat Shield

Bolts/Nuts. . . . . . . . . . . . . . . . . .5 N·m (45 in. lbs.) Generator Mounting

Bolts . . . . . . . . . . . . . . . . . . . . .41 N·m (30 ft. lbs.) Intake Manifold

(5.2L) Bolts . . . .Refer to Procedure in This Section Muffler-to-Catalytic Converter

Band Clamp (Torca). . . . . . . . . .71 N·m (52 ft. lbs.) Oxygen Sensor

Sensor . . . . . . . . . . . . . . . . . . . .48 N·m (35 ft. lbs.) Plenum Pan

Bolts (5.2L) . . . .Refer to Procedure in This Section Rear Tailpipe Hanger

Bolts . . . . . . . . . . . . . . . . . . . .22 N·m (192 in. lbs.) Throttle Body

Bolts/Nuts. . . . . . . . . . . . . . . .23 N·m (200 in. lbs.) Catalytic Converter/Exhaust Pipe

Exhaust Clamp Assembly . . . . .61 N·m (45 ft. lbs.) Muffler-to-Catalytic Converter

Exhaust Clamp Assembly . . . . .61 N·m (45 ft. lbs.)

NOTE: Vehicles may have either a Torca Clamp or an Exhaust Clamp Assembly.