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

Exhaust Manifold

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Removal & Installation



LEFT SIDE (FRONT)
  1. Take the vehicle to a reputable repair shop to have the A/C discharge and recovered.
  2.  

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.

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the serpentine belt.
  4.  
  5. Remove the A/C compressor and lay it aside.
  6.  
  7. Remove the engine strut, and the engine strut bracket.
  8.  
  9. Disconnect the crossover pipe connection.
  10.  
  11. Unfasten the retainer, then remove the exhaust manifold.
  12.  
  13. Clean the mating surfaces at the cylinder head and manifold.
  14.  

See Figure 1

Click image to see an enlarged view

Fig. Fig. 1: Exploded view of the left and right side exhaust manifolds, and the crossover pipe

To install:
  1. Install the exhaust manifold.
  2.  

Liberally coat the manifold fasteners, with a suitable anti-seize compound.

  1. Reconnect the crossover pipe. Tighten the manifold bolts to 26 ft. lbs. (35 Nm).
  2.  
  3. Install the engine strut bracket and the engine strut.
  4.  
  5. Install the A/C compressor.
  6.  
  7. Install the serpentine belt.
  8.  
  9. Connect the negative battery cable.
  10.  
  11. Take the vehicle to a reputable repair shop to have the A/C system recharged.
  12.  

RIGHT SIDE (REAR)
  1. Disconnect the negative battery cable.
  2.  
  3. Remove the oxygen (O2) sensor.
  4.  
  5. Disconnect the crossover pipe connection.
  6.  
  7. Raise and suitably support the vehicle.
  8.  
  9. Disconnect the exhaust pipe.
  10.  
  11. Support the frame at the rear center.
  12.  
  13. Disconnect the rear frame mount bolts. Carefully lower the frame about 10 inches (25.4cm). Remove the exhaust manifold.
  14.  
  15. Clean the mating surfaces at the cylinder head and manifold.
  16.  

To install:
  1. Install the exhaust manifold. Liberally coat the fasteners for the manifold, with an anti-seize compound. Install the manifold bolts, and tighten to 26 ft. lbs. (35 Nm).
  2.  
  3. Raise the engine frame to the mounts, and install the rear frame mount bolts.
  4.  
  5. Install the exhaust pipe.
  6.  
  7. Carefully lower the vehicle.
  8.  
  9. Reconnect the crossover pipe. Install the oxygen (O2) sensor.
  10.  
  11. Connect the negative battery cable.
  12.  
  13. Check for exhaust leaks.
  14.  

3.4L Engine

LEFT SIDE (FRONT)
  1. Disconnect the negative battery cable.
  2.  
  3. Drain and recycle the engine coolant.
  4.  
  5. Remove the air cleaner duct.
  6.  
  7. Remove the right engine mount strut bracket.
  8.  
  9. Disconnect the upper radiator hose from the engine.
  10.  
  11. Remove the automatic transaxle vacuum modulator pipe.
  12.  
  13. Remove the thermostat bypass pipe.
  14.  
  15. Remove the exhaust crossover pipe heat shield, and remove the exhaust crossover pipe bolts to the left exhaust manifold.
  16.  
  17. Unfasten the left exhaust manifold heat shield bolts, then remove the heat shield.
  18.  
  19. Remove the left exhaust manifold nuts, then remove the left exhaust manifold and gasket.
  20.  
  21. Clean the mating surfaces with a suitable solvent.
  22.  

See Figures 2 and 3

Click image to see an enlarged view

Fig. Fig. 2: Exhaust manifold heat shield removal and installation



Click image to see an enlarged view

Fig. Fig. 3: Exploded view of the exhaust manifold

To install:
  1. Install the exhaust manifold gasket, the exhaust manifold, and the manifold nuts.
  2.  
  3. Liberally coat the fasteners for the manifold with a suitable anti-seize compound. Tighten the nuts to 12 ft. lbs. (16 Nm).
  4.  
  5. The remainder of installation is the reverse of the removal procedure.
  6.  

RIGHT SIDE (REAR)
  1. Disconnect the negative battery cable.
  2.  
  3. Remove the air cleaner duct.
  4.  
  5. Drain and recycle the engine coolant.
  6.  
  7. Disconnect the upper radiator hose from the engine
  8.  
  9. Remove the automatic transaxle vacuum modulator pipe, then pull the dipstick out.
  10.  
  11. Remove the thermostat bypass pipe.
  12.  
  13. Remove the exhaust crossover pipe heat shield, and then the bolts from the right (rear) exhaust manifold.
  14.  
  15. Detach the oxygen sensor electrical connector.
  16.  
  17. Raise and safely support the vehicle securely on jackstands.
  18.  
  19. Remove the three-way catalytic converter pipe from the right (rear) exhaust manifold.
  20.  
  21. Remove the automatic transaxle fluid filler tube. Move the filler tube aside.
  22.  
  23. Remove the EGR tube and the oxygen sensor from the exhaust manifold.
  24.  
  25. Unfasten the heat shield bolts, then remove the upper and lower heat shields.
  26.  

See Figures 4 and 5

Click image to see an enlarged view

Fig. Fig. 4: Remove the upper heat shield ...



Click image to see an enlarged view

Fig. Fig. 5: ... then remove the lower heat shield

  1. Remove the exhaust manifold nuts, then remove the manifold and gasket.
  2.  

See Figure 6

Click image to see an enlarged view

Fig. Fig. 6: After the heat shields are removed, unfasten the retainers and remove the exhaust manifold

To install:

Before installation, liberally coat the fasteners for the manifold, with a suitable anti-seize compound.

  1. Install the exhaust manifold gasket, the exhaust manifold, and the manifold nuts.
  2.  
  3. Tighten the exhaust manifold nuts to 12 ft. lbs. (16 Nm).
  4.  
  5. Install the heat shields. Tighten the upper and lower heat shield nuts to 89 inch lbs. (10 Nm)
  6.  
  7. The remainder of installation is the reverse of the removal procedure.
  8.  

3.8L Engine

LEFT SIDE (FRONT)
  1. Disconnect the negative battery cable.
  2.  
  3. Tag and disconnect the spark plug wires from the spark plugs, and put them aside.
  4.  
  5. Remove the EGR tube.
  6.  

See Figures 7 and 8

Click image to see an enlarged view

Fig. Fig. 7: The EGR valve has a tube (arrow) that recirculates hot exhaust gas through the intake manifold. This pipe must be removed



Click image to see an enlarged view

Fig. Fig. 8: Unscrew the nut attaching the EGR tube to the exhaust pipe.

  1. Unfasten the two bolts attaching the exhaust crossover pipe to the manifold.
  2.  

See Figures 9, 10 and 11

Click image to see an enlarged view

Fig. Fig. 9: View of the exhaust crossover pipe



Click image to see an enlarged view

Fig. Fig. 10: This pipe is secure with 2 bolts, one on each side



Click image to see an enlarged view

Fig. Fig. 11: The bolts are easily accessible with a socket and long extension

  1. Remove the oil level indicator tube and indicator.
  2.  

See Figure 12

Click image to see an enlarged view

Fig. Fig. 12: Remove the retaining nut holding the dipstick tube to the manifold.

  1. Unfasten the exhaust manifold retaining nuts, then remove the manifold. Remove and discard the gasket, if equipped. If replacing the manifold, transfer the oxygen sensor to the new manifold.
  2.  
  3. Clean the gasket mating surfaces with a suitable solvent.
  4.  

See Figures 13 and 14

Click image to see an enlarged view

Fig. Fig. 13: Unfasten the nuts from the exhaust manifold studs to remove the exhaust manifold



Click image to see an enlarged view

Fig. Fig. 14: Exploded view of the left side (front) exhaust manifold-3.8L engine

To install:
  1. Position a new gasket, if equipped, then install the exhaust manifold.
  2.  
  3. Liberally coat the manifold fasteners, with a suitable anti-seize compound, then install them and tighten securely/
  4.  
  5. The remainder of installation is the reverse of the removal procedure.
  6.  

RIGHT SIDE (REAR)
  1. Disconnect the negative battery cable.
  2.  
  3. Tag and disconnect the spark plug wires from the spark plugs, then place them aside.
  4.  
  5. Remove the throttle cable bracket.
  6.  
  7. Remove the crossover pipe heat shield.
  8.  
  9. Remove the transaxle oil level indicator and indicator tube.
  10.  
  11. Disconnect the oxygen sensor lead.
  12.  
  13. Unfasten the two bolts attaching the exhaust crossover pipe to the manifold.
  14.  
  15. Remove the plastic tank mounted on the cowl.
  16.  
  17. Raise and suitably support the vehicle.
  18.  
  19. Remove the catalytic converter heat shield and pipe hanger.
  20.  
  21. Remove the front exhaust pipe from the exhaust manifold.
  22.  
  23. Lower the vehicle and remove the engine lift bracket.
  24.  
  25. Unfasten the exhaust manifold retaining nuts, then remove the manifold. Remove and discard the gasket, if equipped. If replacing the manifold, transfer the oxygen sensor to the new manifold.
  26.  
  27. Clean the gasket mating surfaces with a suitable solvent.
  28.  

See Figure 15

Click image to see an enlarged view

Fig. Fig. 15: Exploded view of the right side (rear) exhaust manifold-3.8L engine

To install:
  1. Install the exhaust manifold and secure with the retaining nuts.
  2.  
  3. Install the engine lift bracket.
  4.  
  5. Raise and suitably support the vehicle.
  6.  
  7. Attach the front exhaust pipe to the exhaust manifold with the nuts previously removed.
  8.  
  9. Install the catalytic converter heat shield and pipe hanger.
  10.  
  11. Lower the vehicle, then attach the plastic vacuum tank onto the cowl.
  12.  
  13. Install the two bolts attaching the exhaust crossover pipe to the manifold.
  14.  
  15. Reconnect the oxygen sensor lead.
  16.  
  17. Install the transaxle oil lever indicator and indicator tube.
  18.  
  19. Replace the crossover pipe heat shield.
  20.  
  21. Install the throttle cable bracket.
  22.  
  23. Attach the spark plug wires to the spark plugs, as tagged during removal.
  24.  
  25. Connect the negative battery cable.
  26.  

 
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