### Cylinder Head

#### REMOVAL AND INSTALLATION

##### 1.6L (GA16DE) Engine

CAUTION
Fuel injection systems remain under pressure after the engine has been turned OFF. Properly relieve fuel pressure before disconnecting any fuel lines. Failure to do so may result in fire or personal injury.

1. Disconnect the negative battery cable, drain the cooling system, and relieve the fuel system pressure.
2. Remove all engine drive belts.
3. Remove the cylinder head cover and any related components.
4. Remove the distributor, plug wires and spark plugs.
5. Remove the spark plugs.
6. Remove the intake manifold and all related components.
7. Remove the idler pulley, camshaft sprockets and timing chains.
8. Remove the camshafts.
9. Loosen the cylinder head bolts in 2–3 steps in the reverse order of the tightening sequence to prevent warpage or cracking of the cylinder head assembly.
10. Carefully remove the cylinder head from the block, pulling the head up evenly from both ends. If the head seems stuck, do not pry it off. Tap lightly around the lower perimeter of the head with a rubber mallet to help break the seal. The cylinder head and the intake and exhaust manifolds are removed together. Remove the cylinder head gasket.

    To install:

11. Thoroughly clean both the cylinder block and head mating surfaces. Avoid scratching either surface.

    Fig. 1: Torque sequence of cylinder head bolts — 1.6L (GA16DE) engine

12. Coat the threads and the seating surface of the head bolts with clean engine oil. Install the cylinder head assembly (always replace the head gasket). Install head bolts (with washers) in their proper locations and tighten in sequence as follows:
    1. Tighten bolts No. 1 through 10 in sequence to 22 ft. lbs. (29 Nm).
    2. Tighten bolts No. 1 through 10 in sequence to 43 ft. lbs. (59 Nm).
    3. Loosen bolts completely.
    4. Tighten bolts No. 1 through 10 in sequence to 22 ft. lbs. (29 Nm).
    5. Tighten bolts No. 1 through 10 to 50–55 degrees clockwise in sequence or if angle wrench is not available, tighten bolts to 40–47 ft. lbs. (54–64 Nm) in sequence.
    6. Finally, tighten bolts No. 11 through 15 to 56–73 inch lbs. (6.3–8.3 Nm).
13. Install the camshafts.
14. Install the idler pulley, camshaft sprockets and timing chains.
15. Install the remaining components in the reverse order of removal. Refill and check all fluid levels.
16. Connect negative battery cable.
17. Start the engine, check for leaks, and adjust the ignition timing to specification.
18. Road test the vehicle for proper operation.

##### 2.0L (SR20DE) Engine

1. Release the fuel pressure. Disconnect the negative battery cable.
2. Drain the cooling system. Remove the radiator assembly.
3. Remove the cylinder head cover and oil separator.
4. On some models it may be necessary to disconnect the front exhaust pipe from exhaust manifold.
5. Remove the intake manifold.
6. Remove the distributor assembly.
7. Remove the timing chain, tensioner, chain guide and camshaft sprockets.
8. Remove the camshafts.
9. Remove the water hose from the cylinder block and water hose from the heater.
10. Remove the starter motor. Remove the water pipe bolt.
11. Remove the knock sensor harness connector and remove the EGR tube.
12. Remove the cylinder outside bolts. Remove the cylinder head bolts in 2 or 3 steps. Remove the cylinder head completely with manifolds attached.

    To install:

13. Check all components for wear. Replace as necessary. Clean all mating surfaces and replace the cylinder head gasket.

    NOTE: If the length of any cylinder head bolt exceeds 6.228 in. (158.2mm), replace the bolt.

14. Install cylinder head. Tighten cylinder head in the following sequence:
    1. Tighten all bolts in sequence to 29 ft. lbs. (39 Nm).
    2. Tighten all bolts in sequence to 58 ft. lbs. (78 Nm).
    3. Loosen all bolts in sequence completely.
    4. Tighten all bolts in sequence to 25–33 ft. lbs. (34–44 Nm).
    5. Tighten all bolts to 90–100 degrees clockwise in sequence.
    6. Tighten all bolts additional 90–100 degrees clockwise in sequence. Do not turn any bolt 180–200 degrees clockwise all at once.

       Fig. 2: Cylinder head bolt tightening sequence — 2.0L (SR20DE) engines

15. Install the starter motor and connect the wiring.
16. Install the remaining components in the opposite order from which they were removed.
17. Install and connect the intake air hose.
18. Connect the negative battery cable.
19. Refill and check all fluid levels. Road test the vehicle for proper operation.

##### 2.4L (KA24DE) Engine

###### Altima

1. Disconnect the negative battery cable.
2. Drain coolant from the engine and radiator.
3. Relieve the fuel system pressure.

   CAUTION
   Fuel injection systems remain under pressure after the engine has been turned OFF. Properly relieve fuel pressure before disconnecting any fuel lines. Failure to do so may result in fire or personal injury.

4. Remove the intake manifold collector, exhaust manifold and all related components.
5. Remove the distributor assembly.
6. Using a block of wood, set a jack under the aluminum oil pan and remove the front engine mount.
7. Remove the cylinder head cover.
8. Remove the timing chain and camshaft sprockets.
9. Remove the camshafts.

   NOTE: The valve train components must be reassembled in their original positions.

10. Loosen the cylinder head bolts in reverse order of tightening.

    Fig. 3: Cylinder head bolt tightening sequence — 2.4L (KA24DE) engines

    NOTE: A warped or cracked cylinder head could result from loosening in incorrect order. The cylinder head bolts should be loosened in two or three steps.

11. Remove the cylinder head and the intake manifold. Remove the cylinder head gasket. The lower timing chain will not be disengaged from crankshaft sprocket.

    To install:

12. Clean the gasket surfaces.
13. Install new cylinder head gasket.
14. Install the cylinder head and temporarily tighten the cylinder head bolts. This is necessary to avoid damaging the cylinder head gasket. Be sure to install washers between the bolts and cylinder head.
15. Install the idler shaft assembly.
16. Install the upper timing chain and cover.
17. Tighten the cylinder head bolts in the reverse order of removal as follows:
    1. Tighten all the bolts to 22 ft. lbs. (29 Nm).
    2. Tighten all the bolts to 59 ft. lbs. (79 Nm).
    3. Loosen all the bolts completely.
    4. Tighten all the bolts to 18–25 ft. lbs.(25–34 Nm).
    5. Turn all the bolts 86–91 degrees clockwise.
18. Install the camshafts.
19. Install the timing chains, chain tensioner, and camshaft sprockets.
20. The balance of installation is the reverse of the removal procedure.
21. Refill the engine coolant.
22. Connect the negative battery cable.
23. Start the engine and make the necessary adjustments. Check for proper operation and leaks.

###### 240SX

1. Disconnect negative battery cable.
2. Relieve the fuel system pressure.

   CAUTION
   Fuel injection systems remain under pressure after the engine has been turned OFF. Properly relieve fuel pressure before disconnecting any fuel lines. Failure to do so may result in fire or personal injury.

3. Disconnect and tag all vacuum hoses, fuel lines, and electrical connections.
4. Remove all spark plugs.
5. Remove the fuel injector tube assembly with injectors.
6. Remove all accessory drive belts.
7. Remove the distributor assembly and related components.
8. Remove the cylinder head cover.
9. Remove the front engine mount.
10. Remove the timing chain and camshaft sprockets.
11. Remove the camshafts.
12. Loosen the cylinder head bolts the reverse order of tightening.

    NOTE: Head warpage or cracking could result from removing the head bolts in the incorrect order. Cylinder head bolts should be loosened in two or three steps.

13. Remove the cylinder head with the intake manifold and the exhaust manifold assembly.
14. Remove the cylinder head gasket.

    To install:

15. Check all components for wear and replace any worn components as necessary. Clean all mating surfaces and replace the cylinder head gasket.
16. Install a new cylinder head gasket.
17. Install the cylinder head and temporarily tighten the cylinder head bolts when installing the front cover. This is necessary to avoid damaging the cylinder head gasket. Be sure to install washers between the bolts and cylinder head.
18. Install the idler shaft assembly.
19. Install the upper timing chain and camshaft sprocket cover.
20. Tighten cylinder head bolts, in sequence as follows:
    1. Tighten all bolts to 22 ft. lbs. (29 Nm).
    2. Tighten all bolts to 59 ft. lbs. (79 Nm).
    3. Loosen all bolts completely.
    4. Tighten all bolts to 18–25 ft. lbs. 25–34 Nm).
    5. Turn all bolts 86–91 degrees (90°preferred) clockwise, or if an angle wrench is not available, tighten bolts to 55–62 ft. lbs. (75–84 Nm).
21. The remaining components are installed in the reverse order from which they were removed.
22. Install the air duct and engine undercover.
23. Refill the coolant and engine oil.
24. Connect the negative battery cable.

##### 3.0L (VE30DE)

NOTE: To remove or install the cylinder head, you'll need a cylinder head bolt wrench tool No. ST10120000 (J24239–01) or equivalent.

1. Release the fuel pressure. Disconnect the negative battery cable.
2. Rotate the crankshaft to position the No. 1 piston on TDC of it's compression stroke.
3. Drain the cooling system. Disconnect all the electrical connectors, vacuum hoses and water hoses connected to the intake manifold collector.
4. The crank angle sensor is located in the rear of the left cylinder head. Mark its position, disconnect the electrical connector and remove the sensor.
5. Remove the timing chain assembly.

   NOTE: Do not rotate either the crankshaft or camshaft from this point on or the valves could be bent by hitting the pistons.

6. Remove the intake manifold collector.
7. Remove the intake manifold and fuel rail assembly.
8. Remove the exhaust.
9. Remove the camshaft sprockets.
10. Remove the exhaust camshafts, the camshaft brackets and the rocker arms.
11. Remove the outside cylinder head bolts.
12. Loosen the cylinder head-to-engine bolts, in sequence, using 2–3 steps.
13. Lift the cylinder heads from the engine and discard the gaskets.
14. Unbolt camshaft cap bolts and remove the camshafts.

    To install:

15. Install the camshafts, position the dowels to 12 o'clock and secure with bearing caps. Tighten the bearing caps to 7–9 ft. lbs. (9–12 Nm).
16. Clean the gasket mounting surfaces. Inspect the cylinder heads for warpage, wear, cracks and/or damage.
17. Using liquid gasket sealant, apply a continuous bead to the mating surface of the cylinder block.
18. Install the cylinder heads and torque the head bolts in the reverse of tightening sequence by performing the following procedures:
    1. Torque all bolts, in sequence, to 29 ft. lbs. (39 Nm).
    2. Torque all bolts, in sequence, to 90 ft. lbs. (123 Nm).
    3. Loosen all bolts.
    4. Torque all bolts, in sequence, to 25–33 ft. lbs. (34–44 Nm).
    5. Torque all bolts, in sequence, to 87–94 ft. lbs. (118–127 Nm).
19. The balance of installation is the reverse of the removal procedure.
20. Connect all the electrical connectors, vacuum hoses and water hoses to the intake manifold collector. Refill the cooling system.
21. Connect the negative battery cable. Start the engine check the engine timing. After the engine reaches the normal operating temperature check for the correct coolant level.
22. Road test the vehicle for proper operation.

##### 3.0L (VG30E) Engine

NOTE: To remove or install the cylinder head, you will need a cylinder head bolt wrench No. ST10120000 (J24239–01) or equivalent. The collector assembly and intake manifold have special bolt sequence for removal and installation.

1. Release the fuel pressure. Disconnect the negative battery cable.
2. Remove the timing belt assembly.
3. Remove the intake manifold and fuel rail assembly.
4. Remove the cylinder head covers.
5. Remove the exhaust manifold components.
6. Remove the camshaft pulleys and the rear timing cover securing bolts.
7. Loosen the cylinder head bolts, in the reverse order of the tightening sequence, using 2–3 steps.
8. Remove the cylinder head with the exhaust manifold attached, if not already removed.
9. Check the positions of the timing marks and camshaft sprockets to make sure they have not shifted.

   To install:

10. Clean the gasket mounting surfaces. Inspect the cylinder head(s) for warpage, wear, cracks and/or damage.
11. Make the following checks by performing the following procedures:
    1. If the engine was disturbed, rotate the crankshaft to position the No. 1 piston on the TDC of its compression stroke.
    2. Align the mark on the crankshaft sprocket with the mark on the oil pump body.
    3. Make sure the knock pin on the camshaft is set at the top.

       Fig. 4: Cylinder head bolt torque sequence — 3.0L (VG30E) engine

12. Using a new gasket, install the cylinder head. Apply clean engine oil to the threads and seats of the bolts and install the bolts with washers in the correct position. Note that bolts 4, 5, 12, and 13 are 5.00 in. (127mm) long. The other bolts are 4.17 in. (106mm) long.
13. Torque the bolts according to the pattern for the cylinder head on each side, in the following stages:
    1. Torque all bolts, in order, to 22 ft. lbs. (29 Nm).
    2. Torque all bolts, in order, to 43 ft. lbs. (59 Nm).
    3. Loosen all bolts completely.
    4. Torque all bolts, in order, to 22 ft. lbs. (29 Nm).
    5. Torque all bolts, in order, to 40–47 ft. lbs. (54–64 Nm). If you have a special wrench available that torques bolts to a certain angle, torque them 60–65°tighter rather than going to 40–47 ft. lbs.
14. Install the remaining components in the reverse order of removal.
15. Refill the cooling system. Connect the negative battery cable. Start the engine check the engine timing. After the engine reaches the normal operating temperature check for the correct coolant level.
16. Road test the vehicle for proper operation.

##### 3.0L (VQ30DE) Engine

Fig. 5: Right cylinder head torque sequence — 3.0L (VQ30DE) engine

Fig. 6: Left cylinder head torque sequence — 3.0L (VQ30DE) engine

1. Relieve the fuel system pressure.

   CAUTION
   Fuel injection systems remain under pressure after the engine has been turned OFF. Properly relieve fuel pressure before disconnecting any fuel lines. Failure to do so may result in fire or personal injury.

2. Disconnect the negative battery cable.
3. Drain the engine oil and the cooling system. Be sure to drain the engine block and the radiator.

   NOTE: Before disconnecting any hoses or connectors, note the locations for reassembly.

4. Remove the intake manifold collector.
5. Remove the fuel tube.
6. Remove the intake manifold.
7. Remove the cylinder head covers.
8. Remove the drive belts and idler pulley.
9. Remove the steel (lower) and aluminum (upper) oil pans.
10. Remove the water pump cover.
11. Remove the timing chain case cover.
12. Remove the timing chains, camshaft sprockets and related components.
13. Remove the crankshaft sprocket.
14. Loosen the bolts that secure the rear timing chain case. The bolts must be loosened in the reverse order of installation sequence.
15. Using seal cutter tool, remove the rear timing case cover.

    NOTE: Remove the O-rings from the front of the engine block.

16. Remove the camshafts.
17. Remove the cylinder head bolts in the reverse order of the tightening sequence. The bolts should be loosened in 2–3 steps.

    NOTE: A warped or cracked cylinder head could result from removing the bolts in incorrect order.

18. Remove the cylinder heads from the vehicle.
19. Remove and discard the head gaskets.
20. Remove all traces of liquid gasket from the timing chain case and from the water pump covers.
21. Remove all traces of liquid gasket from the engine block.
22. Inspect the timing chain for excessive wear or damage and replace as necessary.

    To install:

23. Turn the crankshaft until the No. 1 piston is set 240 degrees before TDC on compression stroke.
24. Using new head gaskets, install the cylinder heads.

    NOTE: If possible, replacement of the head bolts is suggested.

25. If replacement of the head bolts is not possible, perform the following bolt measurement:
    1. Measure the diameter of the head bolt 0.43 in. (11mm) from the bottom of the bolt.
    2. Measure the diameter of the head bolt 1.89 in. (48mm) from the bottom of the bolt.
    3. Whenever the size difference between the two measurements exceeds 0.0043 in. (0.11mm) the head bolts must be replaced.
26. Install the cylinder head bolts and tighten in sequence as follows:
    1. Tighten all bolts in sequence to 72 ft. lbs. (98 Nm).
    2. Completely loosen all bolts.
    3. Tighten all bolts in sequence to 25–33 ft. lbs. (24–44 Nm).
    4. Turn all bolts in sequence 90–95 degrees clockwise.
    5. Turn all bolts in sequence 90–95 degrees clockwise.
27. Install the camshafts and related components.
28. Install new O-rings to the front of the engine block.
29. Apply sealant to the hatched portion of the of the rear timing chain case.
30. Align the rear timing chain case with the dowel pins and install onto the cylinder heads and engine block.
31. Tighten the rear timing chain case mounting bolts in sequence to 105–121 inch lbs. (11.8–13.7 Nm).
32. The remaining components are installed in the reverse order from which they were removed.
33. Connect the negative battery cable.
34. Start the engine and run at 3000 RPM under no load to purge the air from the high pressure chamber. The engine may produce a rattling noise. This indicates that air still remains in the chamber and is not a matter of concern.
35. Verify that there are no leaks.

##### 3.0L (VG30DE and VG30DETT) Engines

WARNING
After the timing belt has been removed, DO NOT rotate the crankshaft or camshafts separately. The valves and pistons will make contact thus causing severe engine damage.

CAUTION
Fuel injection systems remain under pressure after the engine has been turned OFF. Properly relieve fuel pressure before disconnecting any fuel lines. Failure to do so may result in fire or personal injury.

1. Relieve the fuel system pressure and disconnect the negative battery cable.
2. Remove the intake manifold collector and all related components.

   NOTE: After the intake manifold collector has been removed, cover the openings on the intake manifold to prevent foreign objects from entering the combustion chamber.

3. Remove the fuel rail and injectors.

   Fig. 7: Right cylinder head torque sequence — 3.0L (VG30DE and VG30DETT) engines

   Fig. 8: Left cylinder head torque sequence — 3.0L (VG30DE and VG30DETT) engines

   Fig. 9: Location of cylinder head 6mm bolt — 3.0L (VG30DE and VG30DETT) engines

4. Remove the cylinder head covers.
5. Remove the accessory drive belts.
6. Remove the radiator and cooling fans.
7. Remove the timing belt, automatic tensioner and idler pulley assemblies.
8. Remove the intake manifold assembly.
9. Disconnect the exhaust pipe from the exhaust manifold.
10. Loosen the cylinder head bolts (in reverse order of installation sequence) in 2–3 stages. Lift the cylinder head off the engine block with the exhaust manifolds attached. It may be necessary to tap the head lightly with a rubber mallet to loosen it.

    To install:

11. Thoroughly clean the engine block and cylinder head surfaces.
12. Make sure the No. 1 cylinder is set at TDC on its compression stroke as follows:
    1. Align the crankshaft timing mark with the mark on the oil pump housing.
    2. Align camshaft sprocket timing mark with the mark on the rear timing belt cover.
13. Install the cylinder head with a new gasket. Apply clean engine oil to the threads and seats of the bolts and install the bolts with washers in the correct position. Be sure to position the head bolt washers with the flat side toward the cylinder head.

    NOTE: There is one special 6mm bolt for each cylinder head. Follow the proper torque specifications for these bolts.

14. Torque the bolts in the proper sequence as follows:
    1. Torque all bolts, in sequence, to 29 ft. lbs. (39 Nm).
    2. Torque all bolts, in sequence, to 90 ft. lbs. (123 Nm).
    3. Loosen all bolts completely.
    4. Torque all bolts, in sequence, to 25–33 ft. lbs. (34–44 Nm).
    5. Torque all bolts, in sequence, to 90 ft. lbs. (123 Nm). If using an angle torque wrench, torque them 70 degrees tighter rather than going to 90 ft. lbs. (123 Nm).
    6. Torque the 6mm X bolts to 7–9 ft. lbs. (10–12 Nm). There is one of these bolts per head.
15. Install the remaining components in the opposite order from which they were removed.
16. Fill the cooling system to the proper level and connect the negative battery cable.
17. Run the engine and make all the necessary engine adjustments.
18. Road test the vehicle for proper operation.