VW Passat & Audi A4 1990-2000

Cylinder Head

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General Disassembly guidelines

The cylinder head assembly is a precision component that should be handled with extreme care. The following points MUST be adhered to.



NEVER loosen the cylinder head-to-engine block fasteners when the engine is hot
 
Always loosen the cylinder head-to-engine block fasteners in the opposite order of the tightening sequence
 
Always protect the machined mating surface of the cylinder head by placing it on a soft, but supportive surface such as a sturdy wood plank or a series of wood blocks
 
Always use original equipment retainers for the cylinder head, camshaft sprocket(s), crankshaft pulley, and engine flywheel bolts and the main and rod bearing fasteners.
 
Clean the area around the cylinder head-to-block mating surface thoroughly before removal
 

BEFORE disassembly:

  1. Clean the area around the cylinder head-to-block mating surface thoroughly before removal
  2.  
  3. Place the engine at Top Dead Center (TDC) on the compression stroke for cylinder No. 1
  4.  
  5. Matchmark the following timing marks and components:
  6.  
    1. Camshaft sprocket(s).
    2.  
    3. Crankshaft sprocket and/or crankshaft pulley and/or flywheel.
    4.  
    5. If equipped, the intermediate and/or balance shaft sprocket(s) and shaft(s).
    6.  
    7. If equipped, the distributor rotor location and if removed, the distributor drive gear.
    8.  


Match-marking the timing marks on the applicable engine components ensures proper assembly and retains proper balance of the engine.

Cleanliness and organization are an absolute must! For additional information, please refer to the following topic(s): Engine Reconditioning.

REMOVAL & INSTALLATION

WARNING
When installing hydraulic valve lifters, Do NOT start the engine for at least 30 minutes after installation, otherwise the valves may contact the pistons. Before starting the engine, turn the engine over two complete turns by hand before starting. If any unusual resistance is felt, STOP!


NOTE
Before removing the cylinder head, align the engine timing marks at TDC. Matchmark the necessary components and their timing marks to ensure proper reassembly. Rotate the crankshaft in the opposite direction of normal rotation about 1 / 4 turn. This will place the crankshaft and pistons slightly Before Top Dead Center (BTDC). This will prevent the valves from contacting the piston crowns. Once the cylinder head is installed, and if removed, the camshafts properly installed and aligned, make sure to turn the crankshaft in the normal direction of rotation to Top Dead Center (TDC).


NOTE
Cylinder head removal should not be attempted unless the engine is cold.

1990-97 Passat Models
2.0l engines
  1. Disconnect the negative battery cable.
  2.  
  3. Open the radiator cap and drain the cooling system into a suitable container.
  4.  
  5. Disconnect the throttle cable. Label and disconnect all wiring and vacuum lines from the intake manifold.
  6.  
  7. Remove the upper intake manifold.
  8.  
  9. Disconnect the fuel supply and return lines.
  10.  
  11. Disconnect the radiator and heater hoses from the cylinder head.
  12.  
  13. Disconnect and label wiring for oil pressure and temperature sensors.
  14.  
  15. Remove the distributor cap and wires.
  16.  
  17. Disconnect the exhaust pipe from the exhaust manifold.
  18.  
  19. if equipped, remove the EGR pipe from the exhaust manifold.
  20.  
  21. Remove the accessory drive belts and any accessory that is bolted to the head.
  22.  
  23. Remove the cylinder head cover, timing belt cover and belt.
  24.  
  25. Loosen the cylinder head bolts in the reverse of the tightening sequence.
  26.  
  27. Remove the bolts and lift the head straight off.
  28.  



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Fig. Exploded view of the 2.0L ABA engine's cylinder head



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Fig. Lift a stuck gasket with a gasket scraper



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Fig. Typical head gasket



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Fig. Using rags or shop towels, plug the ports in the lower intake manifold to prevent foreign objects from entering.



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Fig. Align the timing marks before removing any valve train components such as the timing belt



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Fig. It is always a good idea to mark the rotation direction of the timing belt before removal



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Fig. Remove the timing belt once the tensioner has been released.



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Fig. The head bolts are located in the sill below the arrow. Caution-many VW models use head bolts with a TORX® head. Use only the proper size tool when removing these bolts.



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Fig. A long breaker bar is needed to attain enough leverage to break the head bolts free



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Fig. Once all of the head bolts have been loosened in the proper sequence, remove them and place them in their equivalent position on a marked piece of paper or cardboard



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Fig. Pull the head from the vehicle as shown



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Fig. Remove and inspect the hydraulic lifters



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Fig. The head can be cleaned once it is removed using a parts washer such as this one from SafetyKleen®. If not accessible, your local machine shop should supply such services.



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Fig. Tighten the cylinder head bolts in the sequence shown-2.0L engines

To install:

  1. Before reinstalling the head, check the flatness of the head and block in both width and length, then diagonally from each corner.
  2.  
  3. Install the new cylinder head gasket with the word TOP or OPEN facing upward; Do NOT use any sealing compound.
  4.  
  5. To align the cylinder head, install Guide Pins from tool 3070, or equivalent, into the holes for cylinder head bolts 8 and 10.
  6.  
  7. Install the cylinder head.
  8.  
  9. Install the cylinder head bolts, except 8 and 10, by hand.
  10.  
  11. Remove the Guide Pins using tool 3070 or equivalent, then install head bolts 8 and 10.
  12.  
  13. Tighten the head bolts following the tightening sequence as following:
  14.  
    1. Step 1: 30 ft. lbs. (40 Nm).
    2.  
    3. Step 2: 44 ft. lbs. (60 Nm).
    4.  
    5. Step 3: 1 / 4 turn (90°).
    6.  
    7. Step 4: 1 / 4 turn (90°).
    8.  

  15. Install the camshaft drive belt and adjust the tension.
  16.  
  17. Connect the exhaust pipe to the manifold. Use new gaskets and self-locking nuts and tighten to 18 ft. lbs. (25 Nm).
  18.  
  19. Connect the EGR pipe, if equipped.
  20.  
  21. Connect wiring to the oil pressure and temperature sensors.
  22.  
  23. Install the ignition system components.
  24.  
  25. Connect the radiator and heater hoses.
  26.  
  27. Connect the throttle cable and all wiring and vacuum lines.
  28.  
  29. Install the thermostat with a new O-ring. Tighten the housing bolts to 7 ft. lbs. (10 Nm). Refill the cooling system.
  30.  
  31. Install the accessory drive belts and adjust the tension.
  32.  
  33. Install the upper intake manifold.
  34.  
  35. Connect all wiring and vacuum lines disconnected from the intake manifold. Connect the throttle cable.
  36.  
  37. Connect the fuel supply and return lines.
  38.  
  39. Install the battery, if removed. Connect the negative and positive battery cables.
  40.  
  41. Refill and bleed the cooling system.
  42.  
  43. When everything has been properly installed and connected, be sure to change the oil and filter before starting the engine.
  44.  

2.8L VR6

This procedure requires special tool 3268, or equivalent. This is a setting tool that holds the camshafts in the correct position for installing the timing chains. Before removing the cylinder head, be sure new bolts are available. The cylinder head bolts are made to stretch and cannot be used again.

  1. Disconnect the battery cables and remove the battery.
  2.  
  3. Disconnect the wiring and vacuum lines as required to remove the air cleaner, Mass Air Flow (MAF) sensor and duct.
  4.  
  5. Open the radiator cap and remove the drain plug from the coolant pipe below the intake manifold to drain the cooling system.
  6.  
  7. Remove the engine trim cover. Remove the distributor cap, ignition wires and wire guide as an assembly.
  8.  
  9. Disconnect the throttle cable. Label and disconnect the wiring and vacuum lines from the intake manifold and remove the upper manifold.
  10.  
  11. The injectors and fuel rail assembly may be left on the manifold. Disconnect the fuel supply and return lines and the wiring connector for the injectors.
  12.  
  13. Disconnect the radiator and heater hoses.
  14.  
  15. Thread a long 8 x 10mm bolt into the accessory drive belt tensioner to release the tension. Move the tensioner only as required to remove the belt.
  16.  
  17. Remove the alternator and the belt tensioner.
  18.  
  19. Remove the heat shield and the bolts to disconnect the 2-piece exhaust manifold from the engine. Note the position of the gaskets.
  20.  
  21. Remove the distributor and the timing chain tensioner bolt from the timing chain cover.
  22.  
  23. Remove the cylinder head cover, upper timing chain cover and the retaining plate.
  24.  
  25. If possible, rotate the crankshaft to TDC of No. 1 piston. Clean the oil off the chain and sprockets and mark the direction of rotation for assembly.
  26.  
  27. Hold the camshafts at the flats with a 24mm wrench and remove the bolts to remove the sprockets and chain. Note the position of the distributor drive on the short camshaft.
  28.  


WARNING
Do NOT use the setting tool to hold the camshafts when removing or installing the sprocket bolts. The camshafts and the tool will be damaged.

  1. Carefully check to be sure all necessary wires, hoses and brackets and components have been removed.
  2.  
  3. Loosen the cylinder head bolts in the reverse of the torque sequence. Remove and discard the bolts.
  4.  
  5. Remove the cylinder head.
  6.  

To install:

  1. Carefully clean the old gasket material from the head and the block. Before reinstalling the head, check the flatness of the head and block in both width and length, then diagonally from each corner. Maximum allowable distortion is 0.004 inch (0.1mm).
  2.  
  3. If the new head gasket already has sealant in the small holes at the timing chain end, remove the sealant. Apply a silicone sealer to the timing chain end and install the gasket onto the block with the word TOP or OPEN facing up.
  4.  
  5. Fit the cylinder head over the locating dowels and set the head onto the engine. Install new bolts and hand-tighten them. Do NOT attempt to re-use the old bolts.
  6.  
  7. Tighten the bolts in sequence as described in the following steps:
  8.  
    1. Step 1: 30 ft. lbs. (40 Nm).
    2.  
    3. Step 2: 44 ft. lbs. (60 Nm).
    4.  
    5. Step 3: 1 / 4 turn (90°).
    6.  
    7. Step 4: 1 / 4 turn (90°).
    8.  




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Fig. Be sure to tighten the cylinder head bolts in the sequence shown-2.8L (AAA) engine



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Fig. The minimum cylinder head height in measurement "a" is used to determine the amount the cylinder head can be resurfaced



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Fig. An exploded view of the 2.8L VR6 cylinder head and related components

  1. Be sure the crankshaft is at TDC on No. 1 piston. Install the setting tool to lock the camshafts in place, and then install the timing chain and sprockets. Be sure they are positioned to rotate in the original direction.
  2.  
  3. Hold the camshaft with a 24mm wrench and install the sprocket bolt. Be sure the distributor drive is correctly positioned and tighten the bolts to 74 ft. lbs. (100 Nm).
  4.  
  5. Install the tensioner shoe and temporarily install the upper timing chain cover. Install the tensioner bolt and remove the setting tool. Rotate the crankshaft 4 full turns and stop at TDC of No. 1 piston. The setting tool should fit into the camshafts.
  6.  
  7. Remove the tensioner bolt and upper timing chain cover again. Apply new sealant as required, install the cover and tighten the bolts to 82 inch lbs. (10 Nm). Install the tensioner bolt and tighten to 15 ft. lbs. (20 Nm).
  8.  
  9. Install the cylinder head cover.
  10.  
  11. Use new gaskets and install the intake and exhaust manifolds. Tighten the nuts and bolts to 18 ft. lbs. (25 Nm).
  12.  
  13. Install the alternator belt and adjust tension.
  14.  
  15. Install the accessory drive belt and adjust tension.
  16.  
  17. Connect the radiator and heater hoses.
  18.  
  19. Install the injectors, fuel rail assembly and manifold. Connect the fuel supply and return lines. Connect the wiring connector for the injectors.
  20.  
  21. Install the upper manifold. Tighten the manifold bolts to 18 ft. lbs. (25 Nm).
  22.  
  23. Connect the wiring and vacuum lines disconnected from the intake manifold. Connect the throttle cable.
  24.  
  25. Install the distributor cap, ignition wires and wire guide as an assembly. Install the engine trim cover.
  26.  
  27. Disconnect the battery cables and remove the battery.
  28.  
  29. Refill and bleed the cooling system.
  30.  
  31. When everything has been properly installed and connected, be sure to change the oil and filter before starting the engine.
  32.  

A4 & 1998-00 Passat Models
1.8L Engine
  1. Turn the ignition switch to the OFF position, and then disconnect the negative battery cable.
  2.  
  3. Place the (hood) lock carrier in the service position. For additional information, please refer to the following topic(s): Body And Trim, Service Position, Front Bumper, Hood Lock Carrier.
  4.  
  5. Remove the accessory drive belt, then the engine driven cooling fan.
  6.  
  7. Drain the engine coolant into a suitable container.
  8.  
  9. Remove the intake manifold.
  10.  
  11. Label and detach the following lines and electrical connectors:
  12.  
  13. Wastegate bypass regulator valve
  14.  
  15. Evaporative Emission (EVAP) canister purge regulator valve
  16.  
  17. Power outage stage
  18.  
  19. Mass Air Flow (MAF) sensor
  20.  
  21. Remove the air cleaner housing.
  22.  
  23. Detach the Engine Coolant Temperature (ETC) and the temperature II sensor harness connector.
  24.  
  25. Label and detach all connections from the cylinder head and position them aside.
  26.  
  27. Remove the crankcase breather line.
  28.  
  29. Disconnect the oil supply line at the cylinder head.
  30.  
  31. Remove the exhaust manifold heat shield.
  32.  
  33. Unbolt the turbocharger from the exhaust manifold.
  34.  
  35. Disconnect the coolant hose to the heat exchanger at the rear of the cylinder head.
  36.  
  37. Remove the upper timing belt cover.
  38.  
  39. Turn the crankshaft, in the direction of rotation (clockwise), until the No. 1 cylinder is at Top Dead Center (TDC).
  40.  
  41. Using Torx® wrench T45, loosen the timing belt tensioner.
  42.  
  43. Push down on the tensioner, and remove the belt from the camshaft gear.
  44.  
  45. Remove the Torx® bolt and swing the tensioner assembly bracket forward.
  46.  
  47. Remove the valve cover.
  48.  
  49. Remove the cylinder head bolts in sequence, as shown.
  50.  
  51. Remove the cylinder head, and then clean the gasket mating surfaces.
  52.  
  53. Clean and dry out the cylinder head bolt holes.
  54.  



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Fig. Cylinder head bolt LOOSENING sequence-1.8L Engine



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Fig. Cylinder head bolt TIGHTENING sequence-1.8L Engine



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Fig. An exploded view of the 1.8L cylinder head and its related components

To install:


WARNING
Always replace the cylinder head bolts. Always replace self-locking nuts, bolts, gaskets and O-rings. Do NOT remove the new head gasket from the package until immediately before installing.

  1. Before installing the cylinder head, set the crankshaft and camshaft to TDC for the No. 1 cylinder.
  2.  
  3. Loosen the turbocharger support bracket to reduce the likelihood of any tension while installing the cylinder head.
  4.  
  5. Install the head gasket with the part number visible from the intake side.
  6.  
  7. Install the cylinder head.
  8.  
  9. Install the new cylinder head bolts and tighten in sequence by hand.
  10.  
  11. Torque the new cylinder head bolts following the tightening sequence in four steps:
  12.  
  13. Step 1: 30 ft. lbs. (40 Nm)
  14.  
  15. Step 2: 44 ft. lbs. (60 Nm)
  16.  
  17. Step 3: additional 1 / 4 turn (90°)
  18.  
  19. Step 4: additional 1 / 4 turn (90°)
  20.  


NOTE
It is not necessary to retighten the cylinder head bolts.

  1. Using new gaskets, install the turbocharger to the exhaust manifold, coat the bolts with Hot Bolt Paste G 052 112 A3, or equivalent, then tighten the mounting bolts to 26 ft. lbs. (35 Nm). Tighten the turbo support bracket mounting bolts to 33 ft. lbs. (40 Nm).
  2.  
  3. Install the valve cover.
  4.  
  5. Install the timing belt.
  6.  
  7. Install the accessory drive belts.
  8.  
  9. Install the exhaust manifold heat shield.
  10.  
  11. Connect the oil supply lines to the cylinder head and tighten the retaining straps to 15 ft. lbs. (20 Nm).
  12.  
  13. Install the crankcase breather.
  14.  
  15. Attach any items removed during disassembly.
  16.  
  17. Connect the coolant temperature sensors, and install the air cleaner housing.
  18.  
  19. Fill the engine with coolant and bleed as necessary. For additional information, please refer to the following topic(s): General Information And Maintenance, Fluids And Lubricants.
  20.  
  21. Connect the negative battery cable.
  22.  
  23. Fully close all power windows to stop, operate all window switches for at least 1 second in the close direction to activate the 1-touch opening/closing function.
  24.  
  25. Check the oil level before starting the engine and top off as necessary.
  26.  
  27. Set the clock to the correct time.
  28.  
  29. Check and clear any stored Diagnostic Trouble Codes (DTCs) as necessary, using an appropriate scan tool.
  30.  
  31. Install the hood lock carrier assembly and front bumper.
  32.  
  33. Adjust the headlights.
  34.  

2.8L V6 Engines

The 1996 Audi A4 is equipped with the code AFC engine, which is a Single Overhead (SOHC) Camshaft 2.8L V6 engine.

As of 1997, all 1997-00 A4 & 1998-00 Passat models, equipped with a 2.8L V6 engine, use the code AHA engine, which is a Double Overhead (DOHC) Camshaft 2.8L V6 engine with 5 valves per cylinder.

Although both engines are 2.8L 90° V6 designs, the cylinder heads differ. The code AHA engine features 5 valves per cylinder and variable intake camshaft timing. The following is a comparison of the two engines.

2.8L V6 SOHC Engine:



Code: AFC
 
Type: Single Overhead Camshaft (SOHC)
 
Valves per cylinder: 2 (1 intake, 1 exhaust)
 
Camshaft timing: Fixed
 

2.8L 5V V6 DOHC Engine:



Code: AHA
 
Type: Double Overhead Camshaft (DOHC)
 
Valves per cylinder: 5 (3 intake, 2 exhaust)
 
Camshaft timing: Variable intake camshaft
 

  1. Turn the ignition switch to the OFF position, and then disconnect the negative battery cable.
  2.  
  3. Remove the lower engine splash shield.
  4.  
  5. Drain engine coolant into a sealable container.
  6.  
  7. Place the (hood) lock carrier in the service position. For additional information, please refer to the following topic(s): Body And Trim, Service Position, Front Bumper, Hood Lock Carrier.
  8.  
  9. Properly relieve fuel pressure.
  10.  
  11. Remove the accessory drive belt.
  12.  
  13. Remove the timing belt. The vibration damper should remain installed.
  14.  
  15. Remove the exhaust pipe from the manifold.
  16.  
  17. Remove the Exhaust Gas Recirculation (EGR) valve hose at manifold.
  18.  
  19. Remove the air guide hose between air mass sensor and intake manifold.
  20.  
  21. Remove and tag all spark plug wires and injector connectors.
  22.  
  23. Remove the crankcase breathers on the left and right cylinder head covers.
  24.  
  25. Remove the fuel feed and return lines.
  26.  
  27. Remove the left side cover for fuel line.
  28.  
  29. Disconnect the throttle cable.
  30.  
  31. Mark and remove all vacuum hoses from vacuum pump and intake manifold.
  32.  
  33. Disconnect connectors on the idling stabilization valve and throttle valve potentiometer.
  34.  
  35. Disconnect vacuum hose on vacuum control unit.
  36.  
  37. Disconnect connectors on oil pressure sender and oil pressure switch.
  38.  
  39. Disconnect connector for Hall sender sensor.
  40.  
  41. Remove the EGR valve from the intake manifold.
  42.  
  43. Remove the intake manifold assembly.
  44.  
  45. Remove the coolant pipe at the rear of the cylinder head.
  46.  
  47. Remove the Oxygen (O 2 S) sensor.
  48.  
  49. Remove the heat shield on the exhaust manifold.
  50.  
  51. Remove the cylinder head cover.
  52.  
  53. Remove the timing belt rear belt guard. Remove the hydraulic line from reservoir to pump.
  54.  
  55. Loosen the head bolts in the reverse of the installation torque sequence and remove the cylinder head assembly from the engine.
  56.  



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Fig. Exploded view of the cylinder head mounting and related components-2.8L V6 SOHC Engine



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Fig. Exploded view of the cylinder head mounting and related components-2.8L V6 DOHC Engine



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Fig. Cylinder head mounting bolt torque tightening sequence-2.8L V6 SOHC Engine



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Fig. Cylinder head mounting bolt torque tightening sequence-2.8L V6 DOHC Engine



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Fig. Exploded view of the 2.8L SOHC V6 cylinder head

To install:

  1. Clean all sealing surfaces. Check cylinder head for distortion. Measure at several locations. The maximum permissible distortion is 0.1mm.
  2.  
  3. Install cylinder head gasket. The lettering must face upwards.
  4.  
  5. Install the cylinder head assembly and check the centering pins in the cylinder block.
  6.  
  7. Install cylinder head bolts by hand.
  8.  
  9. Tighten the cylinder head bolts following the torque tightening sequence in 3 steps as follows:
  10.  
    1. Step 1: 44 ft. lbs. (60 Nm)
    2.  
    3. Step 2: 1 / 4 turn (90°)
    4.  
    5. Step 3: 1 / 4 turn (90°)
    6.  



NOTE
It is not necessary to retighten the cylinder head bolts after repairs or as part of Inspection service.

  1. Install the timing belt rear belt guard.
  2.  
  3. Install the cylinder head cover.
  4.  
  5. Install the O 2 S sensor, then install the heat shield on the exhaust manifold.
  6.  
  7. Install the intake manifold assembly.
  8.  
  9. Install the EGR valve to the intake manifold.
  10.  
  11. Reconnect the hall sender sensor, oil pressure sender and oil pressure switch.
  12.  
  13. Reconnect connectors on idling stabilization valve and throttle valve potentiometer.
  14.  
  15. Install all vacuum hoses to vacuum pump and intake manifold.
  16.  
  17. Reconnect the throttle cable.
  18.  
  19. Reconnect the fuel feed and return lines.
  20.  
  21. Install the crankcase breather on the cylinder head cover.
  22.  
  23. Install all spark plug wires and injector connectors.
  24.  
  25. Install the exhaust manifold.
  26.  
  27. Install the timing belt and accessory drive belt.
  28.  
  29. Refill and bleed the cooling system, top off as necessary. For additional information, please refer to the following topic(s): General Information And Maintenance, Fluids And Lubricants
  30.  
  31. Connect the negative battery cable.
  32.  
  33. Enter the radio security code.
  34.  
  35. Check all fluid levels and top off as necessary. Operate the engine at normal operating temperatures and check for leaks.
  36.  
  37. Road test the vehicle for proper operation.
  38.  

 
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