GM Lumina/Silhouette/Transport APVs 1990-1999 Repair Guide

Cylinder Head

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If your vehicle is equipped with air conditioning, refer to General Information and Maintenance for information regarding the implications of servicing your A/C system yourself. Only an MVAC-trained, EPA-certified, automotive technician should service the A/C system or its components.


CAUTION
Observe all applicable safety precautions when working around fuel. Whenever servicing the fuel system, always work in a well-ventilated area. Do not allow fuel spray or vapors to be exposed to a spark or open flame. Keep a dry chemical fire extinguisher near the work area. Always keep fuel in a container specifically designed for fuel storage; also, always properly seal fuel containers to avoid the possibility of fire or explosion.


CAUTION
Never open, service or drain the radiator or cooling system when hot; serious burns can occur from the steam and hot coolant. Also, when draining engine coolant, keep in mind that cats and dogs are attracted to ethylene glycol antifreeze and could drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantities. Always drain coolant into a sealable container. Coolant should be reused unless it is contaminated or is several years old. Removal & Installation

This repair procedure requires the use of a torque angle meter.

3.1L Engine

LEFT SIDE

The cast iron cylinder heads have individual intake and exhaust ports for each cylinder. Rocker arms are retained on individual threaded studs.

  1. Disconnect the negative battery cable.
  2.  
  3. Drain and recycle the engine coolant.
  4.  
  5. Properly relieve the fuel system pressure, as outlined in Fuel System of this repair guide.
  6.  
  7. Remove the following components, as outlined in this information:
    1. Rocker arm covers
    2.  
    3. Intake manifold
    4.  
    5. Exhaust manifold and crossover pipe
    6.  

  8.  
  9. Remove the oil level indicator and tube. Remove the engine strut bracket.
  10.  
  11. Loosen the rocker arms and remove the pushrods. Make sure to keep the pushrods in proper order for installation.
  12.  
  13. Unfasten the cylinder head mounting bolts, then remove head from the engine. Remove and discard the gasket.
  14.  
  15. Thoroughly clean the gasket mounting surfaces, head bolts and cylinder block threads. Once the cylinder head has been removed, it is best to clean and check the head for straightness and cracks. Refer to the engine reconditioning portion of this information for more details.
  16.  

It is usually best to engage the services of a local machine shop to perform these checks.

See Figure 1

Click image to see an enlarged view

Fig. Fig. 1: Exploded view of the cylinder head assembly, including the tightening sequence

To install:
  1. Place a new gasket in position over the dowel pins, with the note "This Side Up" showing.
  2.  
  3. Install the cylinder head over the dowel pins.
  4.  
  5. Install the cylinder head bolts. Tighten in the sequence shown in the accompanying figure to 33 ft. lbs. (45 Nm), plus an additional 90 ° rotation.
  6.  
  7. Install the intake gasket.
  8.  
  9. Install the pushrods, make sure the lower ends of the pushrods are in the lifter seats.
  10.  
  11. Install the rocker arms, adjust the valve lash as described in this information.
  12.  
  13. Replace the intake manifold, rocker arm covers, exhaust manifold, and crossover pipe.
  14.  
  15. Attach the oil level indicator tube and bracket to the head.
  16.  
  17. Install the engine strut bracket.
  18.  
  19. Replace coolant, change oil and filter.
  20.  
  21. Connect the negative battery cable.
  22.  

RIGHT SIDE
  1. Disconnect the negative battery cable.
  2.  
  3. Drain and recycle the engine coolant.
  4.  
  5. Remove the air cleaner and inlet hose.
  6.  
  7. Remove the exhaust crossover tube.
  8.  
  9. Raise the vehicle, remove the right side exhaust manifold and lower the vehicle.
  10.  
  11. Remove the alternator, as described in Engine Electrical of this repair guide.
  12.  
  13. Remove the rocker arm covers, and intake manifold as described in this information of the guide.
  14.  
  15. Loosen the rocker arms and remove the pushrods. Make sure to keep the pushrods in order for installation.
  16.  
  17. Remove the coil bracket.
  18.  
  19. Unfasten the cylinder head mounting bolts, then remove head from the engine. Remove and discard the gasket.
  20.  
  21. Thoroughly clean the gasket mounting surfaces, head bolts and cylinder block threads. Once the cylinder head has been removed, it is best to clean and check the head for straightness and cracks. Refer to the engine reconditioning portion of this information for more details.
  22.  

To install:
  1. Place a new gasket in position over the dowel pins, with the note "This Side Up" showing.
  2.  
  3. Install the cylinder head over the dowel pins.
  4.  
  5. Install the cylinder head bolts. Tighten in the sequence shown in the accompanying figure to 33 ft. lbs. (45 Nm), plus an additional 90 ° rotation.
  6.  
  7. Install the coil bracket.
  8.  
  9. Install the intake gasket.
  10.  
  11. Install the pushrods, making sure the lower ends of the pushrods are in the lifter seats.
  12.  
  13. Install the rocker arms.
  14.  
  15. Replace the intake manifold, rocker arm covers, and alternator.
  16.  
  17. Raise and safely support the vehicle.
  18.  
  19. Install the exhaust manifold, and exhaust pipe and lower the vehicle.
  20.  
  21. Install the crossover pipe.
  22.  
  23. Install the air cleaner and inlet pipe.
  24.  
  25. Connect the negative battery cable.
  26.  
  27. Adjust the valve lash as described in General Information and Maintenance of this repair guide.
  28.  
  29. Fill the fluid levels, change the oil and filter.
  30.  

3.4L Engine

LEFT SIDE
  1. Disconnect the negative battery cable.
  2.  
  3. Drain and recycle the engine coolant.
  4.  
  5. Remove the rocker arm covers, upper intake manifold, lower intake manifold, and exhaust manifold and crossover pipe, as described in this guide.
  6.  
  7. Remove the oil level indicator assembly retaining bolt, and remove the indicator assembly.
  8.  
  9. Loosen the rocker arms and remove the pushrods. Make sure to keep the pushrods in order for installation.
  10.  
  11. Unfasten the cylinder head mounting bolts, then remove head from the engine. Remove and discard the gasket
  12.  
  13. Thoroughly clean the gasket mounting surfaces, head bolts and cylinder block threads. Once the cylinder head has been removed, it is best to clean and check the head for straightness and cracks. Refer to the engine reconditioning portion of this information for more details.
  14.  

It is usually best to engage the services of a local machine shop to perform these checks.

See Figure 2

Click image to see an enlarged view

Fig. Fig. 2: Cylinder head mounting and bolt torque sequence-3.4L engine

To install:
  1. Place the new gasket in position over the dowel pins, with the note "This Side Up" showing.
  2.  
  3. Position the cylinder head over the dowel pins.
  4.  
  5. Install the cylinder head bolts. Tighten in the sequence shown in the accompanying figure to 33 ft. lbs. (45 Nm), plus an additional 90 ° rotation with the torque angle meter.
  6.  
  7. The remainder of installation is the reverse of the removal procedure.
  8.  
  9. Adjust valve lash according to the directions given in General Information and Maintenance .
  10.  
  11. Fill fluid levels, change oil and filter.
  12.  
  13. Connect the negative battery cable.
  14.  

RIGHT SIDE
  1. Disconnect the negative battery cable.
  2.  
  3. Drain and recycle the engine coolant.
  4.  
  5. Remove the rocker arm covers, upper intake manifold, lower intake manifold, and exhaust manifold and crossover pipe, as described in this guide.
  6.  
  7. Loosen the rocker arms and remove the pushrods. Make sure to keep the pushrods in order for installation.
  8.  
  9. Unfasten the cylinder head mounting bolts, then remove head from the engine. Remove and discard the gasket
  10.  
  11. Thoroughly clean the gasket mounting surfaces, head bolts and cylinder block threads. Once the cylinder head has been removed, it is best to clean and check the head for straightness and cracks. Refer to the engine reconditioning portion of this guide for more details.
  12.  

It is usually best to engage the services of a local machine shop to perform these checks.

To install:
  1. Place the new gasket in position over the dowel pins, with the note "This Side Up" showing.
  2.  
  3. Position the cylinder head over the dowel pins.
  4.  
  5. Install the cylinder head bolts. Tighten in the sequence shown in the accompanying figure to 33 ft. lbs. (45 Nm), plus an additional 90 ° rotation with the torque angle meter.
  6.  
  7. The remainder of installation is the reverse of the removal procedure.
  8.  
  9. Adjust valve lash according to the directions given in General Information and Maintenance .
  10.  
  11. Fill fluid levels, change oil and filter.
  12.  
  13. Connect the negative battery cable.
  14.  

3.8L Engine

LEFT AND RIGHT SIDE
  1. Disconnect the negative battery cable.
  2.  
  3. Drain and recycle the engine coolant.
  4.  
  5. Remove the intake manifold and the exhaust manifold, as outlined in this informaion.
  6.  

See Figure 3

Click image to see an enlarged view

Fig. Fig. 3: Unfasten the bolts, then remove the intake manifold

  1. Remove the rocker arm covers, loosen the rocker arms and remove the pushrods. Make sure to keep the pushrods in order for installation.
  2.  
  3. Remove the electronic ignition and spark plug wires.
  4.  
  5. Remove the alternator bracket attached from the head.
  6.  
  7. Remove the A/C compressor bracket from the head.
  8.  
  9. Unbolt the power steering pump and position it aside. Do not disconnect the fluid lines.
  10.  
  11. Remove the serpentine belt tensioner.
  12.  
  13. Remove the fuel pipe heat shield.
  14.  
  15. Unfasten the cylinder head mounting bolts, then remove head from the engine. Remove and discard the gasket
  16.  

See Figures 4 and 5

Click image to see an enlarged view

Fig. Fig. 4: Unfasten the cylinder head mounting bolts



Click image to see an enlarged view

Fig. Fig. 5: Pulling the head, with rockers intact, from the engine block

  1. Thoroughly clean the gasket mounting surfaces, head bolts and cylinder block threads. Once the cylinder head has been removed, it is best to clean and check the head for straightness and cracks. Refer to the engine reconditioning portion of this guide for more details.
  2.  

See Figures 6 through 13

Click image to see an enlarged view

Fig. Fig. 6: View of the top of the pistons with the head removed; these pistons are dished (concave) to help in emission control. Arrows point to the pushrods.



Click image to see an enlarged view

Fig. Fig. 7: Remove the cylinder head gasket from the block. Discard the old gasket and use a new one for installation



Click image to see an enlarged view

Fig. Fig. 8: In the intake valley you will see the balance shaft (A), used to reduce engine vibration; the valve lifter guide (B) prevents lifters from rotating in their bores



Click image to see an enlarged view

Fig. Fig. 9: The dowel pin (arrow) makes it easy to position up a new gasket on the head, after it has been cleaned



Click image to see an enlarged view

Fig. Fig. 10: View of the valve keeper (A) and the location where the pushrod seats (B)



Click image to see an enlarged view

Fig. Fig. 11: View of the valve spring (A), rocker assembly (B) and cylinder head bolt (C)



Click image to see an enlarged view

Fig. Fig. 12: Disassembling the rocker



Click image to see an enlarged view

Fig. Fig. 13: With the head removed, you can see the intake (larger), and exhaust (smaller), valves. The spark plug is nestled between them

This engine uses special torque to yield head bolts. This design bolt requires a special tightening procedure. Failure to follow the given procedure will cause head gasket failure and possible engine damage.

To install:

Install the head gasket with arrow pointing to front of the engine.


CAUTION
Head gaskets are not interchangeable. Failure to install with arrow pointing to front will cause gasket failure and possible engine failure. New head bolts must be used to complete installation. They are "torque to yield".

  1. Apply sealant to the underside of the head bolts, and apply thread locker to the bolt threads before installation.
  2.  
  3. Install NEW head bolts, and tighten to 35 ft. lbs. (47 Nm) in the sequence shown in the accompanying figure.
  4.  

See Figures 14, 15 and 16

Click image to see an enlarged view

Fig. Fig. 14: Always use a torque wrench when tightening cylinder head bolts



Click image to see an enlarged view

Fig. Fig. 15: Cylinder head bolt tightening sequence-3.8L engine



Click image to see an enlarged view

Fig. Fig. 16:

  1. Rotate each bolt an additional 130°, in sequence, using a torque angle meter.
  2.  
  3. Rotate the center 4 bolts an additional 30°, in sequence, using a torque angle meter.
  4.  
  5. Install the pushrods, guide plate and rocker arm assemblies. Apply thread lock compound to the rocker arm pedestal bolts before assembly.
  6.  
  7. Tighten the rocker arm pedestal bolts to 11 ft. lbs. (15 Nm), plus an additional 90° rotation.
  8.  
  9. The remainder of installation is the reverse of the removal procedure.
  10.  
  11. Adjust lash according to the procedure given in General Information and Maintenance .
  12.  
  13. Fill fluid levels, change oil and filter.
  14.  
  15. Connect the negative battery cable.
  16.  

 
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