GM Blazer/Jimmy/Typhoon/Bravada 1983-1993 Repair Guide

Cylinder Head

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REMOVAL & INSTALLATION



See Figures 1, 2, 3, 4 and 5

The engine should be allowed to cool overnight before the cylinder head is removed in order to prevent warpage.

1.9L Engine

See Figures 6 and 7

  1. Disconnect the negative battery cable and drain the engine cooling system.
  2.  
  3. Remove the rocker arm cover from the cylinder head. For details, please refer to the procedure earlier in this section.
  4.  
  5. Remove EGR pipe clamp bolt at the rear of the cylinder head.
  6.  
  7. Raise and support the front of the truck safely using jackstands.
  8.  
  9. Disconnect the exhaust pipe from the manifold, then remove the jackstands and lower the vehicle.
  10.  
  11. Disconnect the heater hoses from the intake manifold and the front of the cylinder head.
  12.  
  13. If equipped with an A/C compressor and/or a P/S pump, disconnect them and lay them aside. DO NOT disconnect the refrigerant or P/S lines, but make sure they are not stretched, kinked or otherwise damaged when the component is repositioned.
  14.  
  15. Disconnect the accelerator linkage and the fuel line from the carburetor. Tag and disengage all necessary electrical connections, the spark plug wires and necessary vacuum lines.
  16.  
  17. Rotate the camshaft until the No. 4 cylinder is in the firing position. Remove the distributor cap and mark rotor-to-housing relationship, then remove the distributor.
  18.  
  19. Disconnect the fuel lines from the fuel pump, then remove the pump.
  20.  
  21. Using two pry bars, depress the timing chain adjuster lock lever to lock the automatic adjuster shoe in its fully retracted position.
  22.  
  23. Remove timing sprocket-to-camshaft bolt, the sprocket and the fuel pump drive cam from the camshaft. Keep the sprocket on the chain damper and tensioner - DO NOT remove the sprocket from the chain.
  24.  
  25. Disconnect the AIR hose and check valve from the air manifold.
  26.  
  27. Remove the cylinder head-to-timing cover bolts.
  28.  
  29. Using a suitable breaker bar, loosen and remove cylinder head-to-engine bolts. The bolts should be loosened gradually in a sequence, beginning with the outer bolts and working inward.
  30.  
  31. Remove the cylinder head, intake and exhaust manifold as an assembly.
  32.  

To install:
  1. Carefully clean and inspect the gasket mounting surfaces.
  2.  

The gasket surfaces on both the head and block must be clean of any foreign matter and free of nicks or heavy scratches. The cylinder bolt threads in the block and the threads on the bolts must be cleaned (dirt will affect the bolt torque).

  1. Place a new gasket over the dowel pins with the side marked "TOP" facing upward, then carefully position the cylinder head over the gasket.
  2.  

Be sure to lubricate the cylinder head bolts with engine oil before installing them.

  1. Install the cylinder head bolts, then tighten them in several passes of the proper sequence (working from the inner towards the outer bolts) to a torque of 61 ft. lbs. (83 Nm). Then retighten the bolts in sequence to 72 ft. lbs. (98 Nm).
  2.  
  3. Install the cylinder head-to-timing cover bolts.
  4.  
  5. Connect the AIR hose and check valve to the air manifold.
  6.  
  7. Engage the timing sprocket and fuel pump drive cam to the camshaft, then install and tighten sprocket-to-camshaft bolt.
  8.  
  9. Unlock the timing chain adjuster lock lever to return it to its "free" position.
  10.  
  11. Install the fuel pump and connect the fuel lines.
  12.  
  13. Align the marks made earlier, then install the distributor and check that it is still pointing to the No. 4 cylinder firing position.
  14.  
  15. Engage all necessary electrical connections, the spark plug wires and vacuum lines, as tagged during removal. Connect the accelerator linkage and the fuel line to the carburetor.
  16.  
  17. If equipped reposition and secure the A/C compressor and/or the P/S pump.
  18.  
  19. Connect the heater hoses to the intake manifold and the front of the cylinder head.
  20.  
  21. Raise and support the front of the truck safely using jackstands.
  22.  
  23. Connect the exhaust pipe to the manifold, then remove the jackstands and lower the vehicle.
  24.  
  25. Install EGR pipe clamp bolt to the rear of the cylinder head.
  26.  
  27. Install the rocker arm cover to the cylinder head.
  28.  
  29. Connect the negative battery cable, then properly refill the engine cooling system.
  30.  
  31. Run the engine, allow it to reach normal operating temperatures and check for leaks.
  32.  
  33. Check and/or adjust the engine timing and idle speed.
  34.  



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Fig. Fig. 1: Remove the rocker arm cover(s)



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Fig. Fig. 2: On pushrod engines, loosen the rocker arms so the pushrods may be removed



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Fig. Fig. 3: On V-engines, remove the intake manifold from the block and cylinder heads



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Fig. Fig. 4: During installation, use a torque wrench to tighten the cylinder head bolts



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Fig. Fig. 5: An extension will be needed to reach the bolts on some cylinder heads



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Fig. Fig. 6: Use 2 pry bars to lock the timing chain automatic adjuster - 1.9L engine



Click image to see an enlarged view

Fig. Fig. 7: Cylinder head bolt torque sequence (reverse sequence during removal) - 1.9L engine

2.0L Engine

See Figure 8

Let the vehicle sit overnight before attempting to remove the cylinder head. The engine must be cold.

  1. Disconnect the negative battery cable.
  2.  
  3. Drain the engine cooling system, then remove the air cleaner assembly.
  4.  
  5. Raise and support the front of the truck safely using jackstands.
  6.  
  7. Remove the exhaust shield, then disconnect the exhaust pipe from the exhaust manifold.
  8.  
  9. Remove the jackstands and lower the vehicle.
  10.  
  11. Disconnect the accelerator linkage, then tag and disengage all necessary electrical wiring connectors and the vacuum lines.
  12.  
  13. Remove the fuel vapor canister harness (steel) pipes.
  14.  
  15. Remove the distributor cap, then matchmark the rotor-to-distributor housing and the distributor housing-to-engine. Remove the distributor from the engine.
  16.  
  17. Remove the rocker arm cover, then remove the rocker arms and the pushrods. For details, refer to the procedures earlier in this section.
  18.  
  19. Remove the upper radiator hose, the heater hose, the upper fan shroud and the fan.
  20.  
  21. Remove the AIR management valve, the air pump and the upper AIR bracket.
  22.  
  23. Disconnect the fuel line from the fuel pump and the wire from the rear of the cylinder head.
  24.  
  25. Remove the cylinder head-to-engine bolts, then carefully lift the cylinder head from the engine. If leverage must be used to break the gasket seal, be very careful not to damage the engine or score the gasket sealing surfaces.
  26.  

To install:
  1. Carefully clean and inspect the gasket mounting surfaces.
  2.  

The gasket surfaces on both the head and block must be clean of any foreign matter and free of nicks or heavy scratches. The cylinder bolt threads in the block and thread on the bolts must be cleaned (dirt will affect the bolt torque).

  1. Coat both sides of a new gasket with sealing compound No. 10520026, or equivalent, then position the gasket on the locating pins. Carefully lower the cylinder head into position on top of the gasket.
  2.  



Click image to see an enlarged view

Fig. Fig. 8: Cylinder head bolt torque sequence - 2.0L engine

  1. Install the cylinder head bolts, then tighten them in several passes of the proper sequence to 65-75 ft. lbs. (88-102 Nm).
  2.  
  3. Connect the fuel line to the fuel pump and the wire to the rear of the cylinder head.
  4.  
  5. Install the AIR management valve, the air pump and the upper AIR bracket.
  6.  
  7. Install the upper radiator hose, the heater hose, the upper fan shroud and the fan.
  8.  
  9. Install the rocker arms and pushrods, then install the rocker arm cover. For details, refer to the procedures earlier in this section.
  10.  
  11. Align the marks and install the distributor. Verify the marks are aligned, then install the distributor cap.
  12.  
  13. Install the fuel vapor canister harness (steel) pipes.
  14.  
  15. Engage all necessary electrical wiring connectors and the vacuum lines as tagged during removal, then connect the accelerator linkage,
  16.  
  17. Raise and support the front of the vehicle safely using jackstands.
  18.  
  19. Connect the exhaust pipe to the exhaust manifold, then install the exhaust shield.
  20.  
  21. Remove the jackstands and carefully lower the vehicle.
  22.  
  23. Install the air cleaner assembly.
  24.  
  25. Connect the negative battery cable, then properly refill the engine cooling system.
  26.  
  27. Run the engine, allow it to reach normal operating temperatures and check for leaks.
  28.  
  29. Check and/or adjust the engine timing and idle speed.
  30.  

2.2L Diesel Engine

See Figure 9

The injection timing MUST BE reset after this procedure. See the Fuel System in this information for details and special tools required.

  1. Disconnect the negative battery cable, then drain the engine cooling system.
  2.  
  3. Remove the rocker arm cover, then remove the rocker arm shaft and the pushrods. Refer to the procedures earlier in this section for details.
  4.  
  5. Remove the upper radiator hose and the heater hose from the cylinder head.
  6.  
  7. Disconnect the heater tube and remove the exhaust pipe from the exhaust manifold.
  8.  
  9. Remove the vacuum pump and the A/C compressor (if equipped, move it aside with the lines intact).
  10.  
  11. Disconnect the heater hose/bracket.
  12.  
  13. Tag and disengage the necessary electrical wiring connectors. Disconnect the PCV valve hose from the pipe and move it aside.
  14.  
  15. Remove the dipstick tube bracket and dipstick, the breather pipe and the oil jet pipe.
  16.  
  17. Disconnect the fuel injection lines and cover them with protective caps.
  18.  
  19. Remove the air conditioning bracket and disconnect the coolant return hose.
  20.  
  21. Remove the cylinder head-to-engine bolts, then carefully remove the cylinder head from the vehicle.
  22.  

To install:
  1. Carefully clean and inspect the gasket mounting surfaces.
  2.  

The gasket surfaces on both the head and block must be clean of any foreign matter and free of nicks or heavy scratches. The cylinder bolt threads in the block and the threads on the bolts must be cleaned (dirt will affect the bolt torque).

  1. Place a new gasket over the dowel pins with the side marked "TOP" facing upward, then carefully position the cylinder head over the gasket.
  2.  

Be sure to lubricate the cylinder head bolts with engine oil before installing them.

  1. Install the cylinder head bolts, then tighten them in the proper sequence first to a torque of 40-47 ft. lbs. (54-64 Nm) and then, to 54-61 ft. lbs. (73-83 Nm) for new bolts or to 61-69 ft. lbs. (83-93 Nm) for used bolts.
  2.  



Click image to see an enlarged view

Fig. Fig. 9: Cylinder head bolt torque sequence - 2.2L diesel engine

  1. Connect the coolant return hose, then install the air conditioning bracket, if equipped,
  2.  
  3. Remove the protective caps, then connect the fuel injection lines.
  4.  
  5. Install the dipstick tube bracket and dipstick, the breather pipe and the oil jet pipe.
  6.  
  7. Reposition the pipe and connect the PCV valve, then engage all necessary electrical wiring connectors as tagged during removal.
  8.  
  9. Connect the heater hose/bracket.
  10.  
  11. Install the vacuum pump and the A/C compressor (if equipped).
  12.  
  13. Install the exhaust pipe to the exhaust manifold, then connect the heater tube .
  14.  
  15. Install the upper radiator hose and the heater hose to the cylinder head.
  16.  
  17. Install the rocker arm shaft and the pushrods, then install the rocker arm cover. Refer to the procedures earlier in this section for details.
  18.  
  19. Connect the negative battery cable and properly refill the engine cooling system.
  20.  
  21. Check and adjust the injection timing.
  22.  
  23. Run the engine and check for leaks.
  24.  

2.5L Engine

See Figure 10

Let the vehicle sit overnight before attempting to remove the cylinder head. The engine must be cold.


CAUTION
Relieve the pressure on the fuel system before disconnecting any fuel line connection. See General Information & Maintenance or Fuel System for the proper procedures.

VEHICLES THROUGH 1988
  1. Properly relieve the fuel system pressure, then disconnect the negative battery cable.
  2.  
  3. Drain the engine cooling system, then remove the air cleaner assembly.
  4.  
  5. If equipped, remove and reposition the A/C compressor with the lines intact.
  6.  
  7. Disconnect the PCV hose and remove the EGR valve.
  8.  
  9. Tag and disengage the spark plug wires from the spark plugs, then remove them from the rocker arm cover.
  10.  
  11. Disconnect the vacuum line hold-down at the thermostat. Tag and disconnect the vacuum lines, fuel lines and wiring at the TBI unit. Remove the vacuum lines from the studs on the intake manifold.
  12.  
  13. Remove the rocker arm cover.
  14.  
  15. Disconnect the accelerator, the cruise control and the TVS cables, as equipped.
  16.  
  17. If equipped, remove the alternator rear brace.
  18.  
  19. Disconnect the water pump bypass and heater hoses from the intake manifold.
  20.  
  21. If equipped, remove the A/C compressor bracket.
  22.  
  23. Disconnect the exhaust pipe from the manifold.
  24.  
  25. If applicable, disengage the A/C line hold-down, but DO NOT disconnect the refrigerant lines.
  26.  
  27. Remove the alternator.
  28.  
  29. Disconnect the upper radiator hose.
  30.  
  31. Remove the fuel line bracket at the fuel filter, then disengage the fuel and vacuum lines near the filter.
  32.  
  33. Remove the dipstick tube, then disengage the wiring harness bracket at the rear of the cylinder head.
  34.  
  35. Remove the coil bracket from the cylinder head, then disengage the oxygen sensor wiring.
  36.  
  37. Loosen the rocker arms and remove the pushrods.
  38.  
  39. If equipped, remove the brace between the intake manifold and block.
  40.  
  41. Remove the cylinder head-to-engine bolts, then remove the cylinder head from the engine (with the manifolds attached). If necessary, remove the intake and the exhaust manifolds from the cylinder head.
  42.  

To install:
  1. Carefully clean and inspect the gasket mounting surfaces.
  2.  

The gasket surfaces on both the head and block must be clean of any foreign matter and free of nicks or heavy scratches. The cylinder bolt threads in the block and the threads on the bolts must be cleaned (dirt will affect the bolt torque).

  1. Place a new gasket over the dowel pins (DO NOT use any sealer on the gasket), then position the cylinder head on the block over the dowel pins and gasket.
  2.  
  3. Apply a coating of 1052080 or equivalent sealer to the heads and threads of all of the cylinder head bolts for 1985 vehicles, or to the threads of the bolts/studs at the front left and rear left positions (numbers 9 and 10 in the torque sequence, for 1986 and later vehicles. Thread the cylinder head bolts, then tighten them in the proper sequence to 90 ft. lbs. (125 Nm).
  4.  



Click image to see an enlarged view

Fig. Fig. 10: Cylinder head bolt torque sequence - 2.5L engine

  1. If equipped, install the brace between the intake manifold and block.
  2.  
  3. Install the pushrods and secure the rocker arms.
  4.  
  5. Install the coil bracket to the cylinder head.
  6.  
  7. Install the wiring harness bracket to the rear of the cylinder head, then install the dipstick tube.
  8.  
  9. Connect the fuel and vacuum lines near the fuel filter, then install the fuel line bracket at the filter.
  10.  
  11. Connect the upper radiator hose, then install the alternator.
  12.  
  13. If equipped, install the A/C refrigerant line hold-down.
  14.  
  15. Connect the exhaust pipe to the manifold.
  16.  
  17. If equipped, install the A/C compressor bracket.
  18.  
  19. Connect the water pump bypass and heater hoses, then install the alternator rear brace.
  20.  
  21. Connect the accelerator, TV and cruise control cables, as equipped.
  22.  
  23. Install the rocker arm cover.
  24.  
  25. Secure the vacuum lines at the intake manifold studs. Engage the vacuum lines, fuel lines and wiring connectors to the TBI unit as tagged during removal.
  26.  
  27. Install the vacuum line hold-down at the thermostat, then engage the spark plug wires.
  28.  
  29. Install the EGR valve, then connect the PCV hose.
  30.  
  31. If equipped, reposition and secure the A/C compressor.
  32.  
  33. Install the air cleaner assembly, then connect the negative battery cable.
  34.  
  35. Properly refill the engine cooling system, then check for leaks.
  36.  

1989 VEHICLES

See Figure 10

  1. Properly relieve the fuel system pressure, then disconnect the negative battery cable.
  2.  
  3. Drain the engine cooling system, then remove the air cleaner assembly.
  4.  
  5. If equipped, remove and reposition the A/C compressor with the lines intact. Make sure the lines are not kinked or otherwise damaged.
  6.  
  7. Remove the rocker arm cover.
  8.  
  9. Loosen the rocker arms and remove the pushrods. For details, please refer to the procedure located earlier in this section.
  10.  
  11. Tag and disconnect the vacuum lines, fuel lines and wiring at the TBI unit. Remove the vacuum lines from the studs on the intake manifold.
  12.  
  13. Disconnect the accelerator, the cruise control and the TVS cables, as equipped.
  14.  
  15. Remove the alternator along with the brackets and position aside.
  16.  
  17. Remove the water pump bypass and heater hoses from the intake manifold.
  18.  
  19. Disconnect the exhaust pipe from the exhaust manifold.
  20.  
  21. Disconnect the upper radiator hose, then remove the vacuum tube from the coolant outlet stud.
  22.  
  23. Remove the fuel filter and fuel line bracket at the rear of the cylinder head.
  24.  
  25. Remove the dipstick tube, then disconnect the wiring harness and ground strap at the rear of the cylinder head.
  26.  
  27. Tag and disengage the wiring connectors from the sensors and the cylinder head and the thermostat housing.
  28.  
  29. Remove the ignition coil wires, then tag and disconnect the spark plug wires.
  30.  
  31. Disengage the oxygen sensor wiring connector.
  32.  
  33. Disconnect the cylinder head bolts, then remove the cylinder head.
  34.  

To install:
  1. Carefully clean and inspect the gasket mounting surfaces.
  2.  

The gasket surfaces on both the head and block must be clean of any foreign matter and free of nicks or heavy scratches. The cylinder bolt threads in the block and thread on the bolts must be cleaned (dirt will affect the bolt torque).

  1. Place a new gasket over the dowel pins, then position the cylinder head on the block over the dowel pins and gasket.
  2.  
  3. Apply a coating of 1052080 or equivalent sealer to the threads of the cylinder head bolts, then thread the bolts into position. Make sure the bolts are threaded within 15 minutes of the sealant application in order to allow the sealer to properly cure.
  4.  
  5. Tighten the cylinder head bolts to specification, using multiple passes of the proper sequence:
  6.  
  7. Torque all bolts gradually to 18 ft. lbs. (25 Nm).
  8.  
  9. Torque all bolts except the left front bolt (No. 9 in the sequence) to 26 ft. lbs. (35 Nm), then retorque number 9 to 18 ft. lbs. (25 Nm).
  10.  
  11. Torque all bolts an additional 1 / 4 turn (90°).
  12.  
  13. Engage the oxygen sensor connector.
  14.  
  15. Connect the spark plug and ignition coil wiring.
  16.  
  17. Engage the wiring connectors to the sensors on the cylinder head and thermostat housing.
  18.  
  19. Connect the wiring harness bracket and ground strap to the rear of the cylinder head.
  20.  
  21. Install the dipstick tube, then install the fuel filter and fuel line bracket.
  22.  
  23. Secure the vacuum tube at the coolant outlet stud, then connect the upper radiator hose.
  24.  
  25. Connect the exhaust pipe to the manifold.
  26.  
  27. Connect the water pump bypass and heater hoses.
  28.  
  29. Reposition and secure the alternator with the brackets.
  30.  
  31. Connect the accelerator, cruise control and TVS cables, as equipped.
  32.  
  33. Secure the vacuum hoses to the intake manifold studs, then engage the vacuum hoses, fuel lines and electrical wires to the TBI unit as tagged during removal.
  34.  
  35. Install the pushrods and secure the rocker arms.
  36.  
  37. Install the rocker arm cover.
  38.  
  39. If equipped, reposition and secure the A/C compressor along with the brackets.
  40.  
  41. Install the air cleaner assembly, then connect the negative battery cable.
  42.  
  43. Properly refill the engine cooling system, then check for leaks.
  44.  

2.8L Engine

See Figure 11


CAUTION
Relieve the pressure on the fuel system before disconnecting any fuel line connection. Please refer to General Information & Maintenance or Fuel System of this manual for the proper procedures.

  1. Properly relieve the fuel system pressure, then connect the negative battery cable.
  2.  
  3. Drain the engine cooling system.
  4.  
  5. Remove the intake manifold assembly. For details, please refer to the procedure located earlier in this section.
  6.  
  7. If necessary, raise and support the front of the vehicle safely using jackstands. If you decide to disconnect the exhaust manifold and not the pipe in the next step, it may not be necessary to raise the vehicle.
  8.  
  9. Either disconnect the exhaust pipe from the exhaust manifold (so the manifold may be removed with the cylinder head) or, remove the exhaust manifold-to-cylinder block retainers and reposition the manifold out of the way.
  10.  
  11. If raised, remove the jackstands and carefully lower the vehicle.
  12.  
  13. If removing the left side cylinder head, remove the dipstick tube, then disconnect the ground strap and the sensor connector from the cylinder head.
  14.  
  15. If removing the right side cylinder head, remove the drive belt, alternator, and AIR pump with mounting bracket.
  16.  

If valve train components, such as the pushrods, are to be reused, they must be tagged or arranged to insure installation in their original locations.

  1. Loosen the rocker arm nuts, turn the rocker arms and remove the pushrods. Keep the pushrods in the same order as removed.
  2.  
  3. Loosen the cylinder head bolts using multiple passes in the reverse order of the tightening sequence.
  4.  
  5. Remove the cylinder head; DO NOT pry on the head to loosen it.
  6.  

To install:
  1. Carefully clean and inspect the gasket mounting surfaces.
  2.  

The gasket surfaces on both the head and block must be clean of any foreign matter and free of nicks or heavy scratches. The cylinder bolt threads in the block and the threads on the bolts must be cleaned (dirt will affect the bolt torque).



Click image to see an enlarged view

Fig. Fig. 11: Cylinder head bolt torque sequence - 2.8L engine

  1. Place a new gasket over the dowel pins with the words "This Side Up" facing upwards, then position the cylinder head on the block over the dowel pins and gasket.
  2.  
  3. Apply a coating of 1052080 or equivalent sealer to the threads of the cylinder head bolts, then thread the bolts into position and tighten them to specification using the proper torque sequence:
  4.  
  5. First, torque all bolts to 40 ft. lbs. (55 Nm).
  6.  
  7. Then, torque all bolts an additional 1 / 4 turn (90°).
  8.  
  9. Install the pushrods, then reposition the rocker arms and adjust the valves.
  10.  
  11. For the right side, install the alternator and AIR pump along with the mounting bracket, then install and tighten the drive belt.
  12.  
  13. For the left side, connect the ground strap and sensor connector, then install the dipstick tube.
  14.  
  15. If necessary, raise and support the front of the truck safely using jackstands.
  16.  
  17. Either connect the exhaust pipe to the manifold or the manifold to the cylinder head, as applicable. If raised, remove the jackstands and lower the truck.
  18.  
  19. Install the intake manifold assembly.
  20.  
  21. Connect the negative battery cable, then properly refill the engine cooling system.
  22.  
  23. Check and/or adjust the ignition timing and idle speed (if possible).
  24.  

4.3L Engine

See Figure 12


CAUTION
Relieve the pressure on the fuel system before disconnecting any fuel line connection. Please refer to General Information & Maintenance or Fuel System of this manual for the proper procedures.

  1. Properly relieve the fuel system pressure, then disconnect the negative battery cable.
  2.  
  3. Drain the engine cooling system.
  4.  
  5. Remove the rocker arm cover.
  6.  
  7. Remove the intake manifold.
  8.  
  9. Remove the exhaust manifold.
  10.  
  11. If removing the right cylinder head, remove or disconnect:
  12.  
  13. Electrical connector at the sensor.
  14.  
  15. Dipstick tube at the cylinder head bracket.
  16.  
  17. Air conditioning compressor (position it aside with the refrigerant lines attached), if equipped.
  18.  
  19. A/C compressor (if equipped)/belt tensioner bracket.
  20.  
  21. If removing the left cylinder head, remove or disconnect:
  22.  
  23. Alternator (position it aside).
  24.  
  25. Left side engine accessory bracket with power steering pump (position the pump aside with the lines attached) and brackets, if equipped.
  26.  
  27. Tag and disconnect the wiring from the spark plugs. If necessary, remove the spark plugs from the cylinder head.
  28.  
  29. Loosen the rocker arms and remove the pushrods.
  30.  

If valve train components, such as the rocker arms or pushrods, are to be reused, they must be tagged or arranged to insure installation in their original locations.

  1. Remove the cylinder head bolts by loosening them in the reverse of the torque sequence, then carefully remove the cylinder head.
  2.  

To install:
  1. Carefully clean and inspect the gasket mounting surfaces.
  2.  

The gasket surfaces on both the head and block must be clean of any foreign matter and free of nicks or heavy scratches. The cylinder bolt threads in the block and the threads on the bolts must be cleaned (dirt will affect the bolt torque).



Click image to see an enlarged view

Fig. Fig. 12: Cylinder head bolt torque sequence - 4.3L engine

DO NOT apply sealer to composition steel-asbestos gaskets.

  1. If using a steel only gasket, apply a thin and even coat of sealer to both sides of the gaskets.
  2.  
  3. Place a new gasket over the dowel pins with the bead or the words "This Side Up" facing upwards (as applicable), then carefully lower the cylinder head into position over the gasket and dowels.
  4.  
  5. Apply a coating of 1052080 or equivalent sealer to the threads of the cylinder head bolts, then thread the bolts into position until finger-tight. Using the proper torque sequence, tighten the bolts in 3 steps:
  6.  
  7. First, tighten the bolts to 25 ft. lbs. (34 Nm).
  8.  
  9. Next, tighten the bolts to 45 ft. lbs. (61 Nm).
  10.  
  11. Finally, tighten the bolts to 65 ft. lbs. (90 Nm).
  12.  
  13. Install the pushrods, secure the rocker arms and adjust the valves.
  14.  
  15. If removed, install the spark plugs. Engage the spark plug wires.
  16.  
  17. If the left cylinder head was removed, reposition and secure the engine accessory bracket with the power steering pump and brackets, as equipped. Install the alternator.
  18.  
  19. If the right cylinder head was removed, install the A/C compressor (if equipped) and A/C compressor/belt tensioner bracket, then install the dipstick tube bracket and engage the sensor electrical connector.
  20.  
  21. Install the exhaust manifold.
  22.  
  23. Install the intake manifold.
  24.  
  25. Install the rocker arm cover.
  26.  
  27. Connect the negative battery cable, then properly refill the engine cooling system.
  28.  
  29. Run the engine to check for leaks, then check and/or adjust the ignition timing.
  30.  

CLEANING & INSPECTION



See Figure 13

  1. With the valves installed to protect the valve seats, remove carbon deposits from the combustion chambers and valve heads with a drill-mounted wire brush. Be careful not to damage the cylinder head gasket surface. If the head is to be disassembled, proceed to Step 3. If the head is not to be disassembled, proceed to Step 2.
  2.  
  3. Remove all dirt, oil and old gasket material from the cylinder head with solvent. Clean the bolt holes and the oil passage. Be careful not to get solvent on the valve seals as the solvent may damage them. If available, dry the cylinder head with compressed air. Check the head for cracks or other damage, and check the gasket surface for burrs, nicks and flatness. If you are in doubt about the head's serviceability, consult a reputable automotive machine shop.
  4.  
  5. Remove the valves, springs and retainers, then clean the valve guide bores with a valve guide cleaning tool. Remove all dirt, oil and old gasket material from the cylinder head with solvent. Clean the bolt holes and the oil passage.
  6.  
  7. Remove all deposits from the valves with a wire brush or buffing wheel. Inspect the valves as described later in this section.
  8.  
  9. Check the head for cracks using a dye penetrant in the valve seat area and ports, head surface and top. Check the gasket surface for burrs, nicks and flatness. If you are in doubt about the head's serviceability, consult a reputable automotive machine shop.
  10.  

If the cylinder head was removed due to an overheating condition and a crack is suspected, do not assume that the head is not cracked because a crack is not visually found. A crack can be so small that it cannot be seen by eye, but can pass coolant when the engine is at operating temperature. Consult an automotive machine shop that has pressure testing equipment to make sure the head is not cracked.



Click image to see an enlarged view

Fig. Fig. 13: Clean the combustion chamber using a drill-mounted wire brush

RESURFACING



See Figures 14 and 15

Whenever the cylinder head is removed, check the flatness of the cylinder head gasket surface as follows:

  1. Make sure all dirt and old gasket material has been cleaned from the cylinder head. Any foreign material left on the head gasket surface can cause a false measurement.
  2.  



Click image to see an enlarged view

Fig. Fig. 14: Checking the cylinder head for flatness diagonally across the head surface



Click image to see an enlarged view

Fig. Fig. 15: Checking the cylinder head for flatness straight across the head surface

  1. Place a straightedge straight across and diagonally across the gasket surface of the cylinder head (in the positions shown in the figures). Using feeler gauges, determine the clearance at the center of the straightedge.
  2.  
  3. If warpage exceeds the 0.004 in. (0.10mm) then the cylinder head should likely be resurfaced or replaced. Contact a reputable machine shop for machining service and recommendations.
  4.  

When resurfacing the cylinder head(s), the intake manifold mounting position is altered and must be corrected by machining a proportionate amount from the intake manifold flange.

 
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