GM Storm/Spectrum 1985-1993 Repair Guide

Cylinder Head

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REMOVAL & INSTALLATION



Spectrum

See Figure 1

  1. Relieve the fuel system pressure, then disconnect the negative battery cable.
  2.  
  3. Drain the cooling system.
  4.  
  5. Remove the air cleaner. Remove the suction pipe and clips for the air induction system.
  6.  
  7. Disconnect the flex hose and oxygen sensor at the exhaust manifold.
  8.  
  9. Disconnect the exhaust pipe bracket at the block and the exhaust pipe at the manifold.
  10.  
  11. Tag and disconnect the spark plug wires.
  12.  
  13. Remove the thermostat housing, the distributor, the vacuum advance hoses and the ground cable at the cylinder head. Remember to tag all vacuum hoses for assembly purposes.
  14.  
  15. Disconnect the fuel hoses at the fuel pump.
  16.  
  17. From the carburetor, if equipped, remove the necessary hoses and the throttle cable.
  18.  
  19. If applicable, remove the engine harness assembly from fuel injectors.
  20.  
  21. Disconnect the vacuum switching valve electrical connector and the heater hoses.
  22.  
  23. Remove the alternator, power steering and air conditioning adjusting bolts, brackets and drive belts.
  24.  
  25. Support the engine using a vertical hoist. Remove the right hand motor mount and bracket at the front cover.
  26.  
  27. Rotate the engine to align the timing marks, then remove the timing gear cover.
  28.  
  29. Loosen the tension pulley and remove the timing belt from the camshaft timing pulley.
  30.  
  31. Remove the fuel pump.
  32.  
  33. Disconnect the intake manifold coolant hoses.
  34.  
  35. Remove the cylinder head bolts (remove the bolts from both ends at the same time, working toward the middle) and the cylinder head. Clean all of the mounting surfaces.
  36.  

To install:
  1. Use new seals and gaskets, apply oil to the bolt threads and torque the head bolts.
  2.  

When tightening the cylinder head bolts, work from the middle toward both ends, alternating from one side to the other. Tighten the bolts in at least 2 passes; first, torque the bolts to 29 ft. lbs. (40 Nm). The final torque should be 58 ft. lbs. (79 Nm).

  1. After tightening, adjust the valve clearance and complete the installation procedures, by reversing the removal procedures.
  2.  

Storm
SOHC ENGINE

See Figure 1

  1. Relieve the fuel system pressure, then disconnect the battery negative cable.
  2.  
  3. Drain cooling system.
  4.  
  5. Disconnect the accelerator cable from the throttle body, then the breather hose from the intake air duct.
  6.  
  7. Disconnect the intake air duct from the throttle body, then the MAP sensor hose from the MAP sensor.
  8.  
  9. Disconnect the brake booster hose, then the 2 EVAP canister hoses from the pipes on the intake manifold (common chamber).
  10.  
  11. Disconnect the EGR vacuum hoses, then the oxygen sensor harness electrical connector.
  12.  
  13. Disconnect the ignition coil ground cable from the thermostat housing flange.
  14.  
  15. Unplug both engine coolant temperature sensor connectors from the thermostat housing.
  16.  
  17. Remove the cable harness clip from the coolant outlet pipe bracket.
  18.  
  19. Disconnect the 2 cable harness electrical connectors, located near the left strut tower.
  20.  
  21. Remove the engine heater hoses, then disconnect the upper radiator hose from the radiator.
  22.  
  23. Disconnect the fuel feed and return hoses, then raise and support the vehicle safely.
  24.  
  25. Remove the right undercover, then the front exhaust pipe from the exhaust manifold. Remove the supports and carefully lower the vehicle.
  26.  
  27. Remove the right engine mount, then the alternator drive belt.
  28.  
  29. Remove the power steering belt.
  30.  
  31. Remove the engine mounting bracket from the timing case cover, then remove the timing belt.
  32.  
  33. Remove the valve cover, then remove the cylinder head bolts and the cylinder head.
  34.  

To install:
  1. Clean the cylinder head gasket mounting surfaces, then install the cylinder head with a new gasket.
  2.  
  3. Tighten the bolts in at least 2 passes; first, torque the bolts to 29 ft. lbs. (40 Nm). The final torque should be 58 ft. lbs. (79 Nm).
  4.  
  5. Install the timing belt and the valve cover, then the engine mounting bracket onto the timing case cover.
  6.  
  7. Raise and support the vehicle safely, then install the right engine mount.
  8.  
  9. Install the front exhaust pipe to the exhaust manifold, then right side under cover. Remove the supports and lower the vehicle.
  10.  
  11. Connect the fuel feed line and fuel return hose.
  12.  
  13. Connect the coolant bypass pipe bracket to the cylinder head.
  14.  
  15. Install the upper radiator hose, then the 2 heater hoses onto the engine.
  16.  
  17. Connect the 2 cable harness connectors, located near the left strut tower.
  18.  
  19. Connect the 2 ground cable terminals, located to the right side of the intake manifold (common chamber).
  20.  
  21. Install both engine coolant temperature sensor wiring harness connectors to the thermostat housing.
  22.  
  23. Connect the ignition coil ground cable to the terminal on the thermostat housing flange.
  24.  
  25. Install the oxygen sensor electrical connector.
  26.  
  27. Connect the EVAP canister hoses to the canister pipes on the intake manifold (common chamber).
  28.  
  29. Connect the brake booster vacuum and MAP sensor hoses.
  30.  
  31. Install the intake air duct to the throttle body, then the PCV hose to the intake air duct.
  32.  
  33. Connect the accelerator cable to the throttle body.
  34.  
  35. Connect the battery negative cable and fill cooling system. Start engine and check for leaks.
  36.  



Click image to see an enlarged view

Fig. Fig. 1: Cylinder head bolt torque sequence - SOHC engines

1.6L DOHC ENGINE

See Figure 2

  1. Relieve the fuel system pressure, then disconnect the battery negative cable.
  2.  
  3. Drain the engine cooling system.
  4.  
  5. Disconnect the accelerator cable from the cable clips (located on the common chamber) and from the throttle body.
  6.  
  7. Remove the PCV hose from the intake air duct, then disconnect the duct from the throttle body.
  8.  
  9. Remove the hose from the MAP sensor, then remove the vacuum hose from the brake booster.
  10.  
  11. Remove the 2 EVAP hoses from the pipes on the common chamber, then remove the MAP sensor and EVAP pipes from the chamber. Remove the EVAP pipe support bracket.
  12.  
  13. Unplug the oxygen sensor electrical connector, then remove the ignition coil ground cable from the thermostat housing flange.
  14.  
  15. Unplug the coolant temperature sensor and thermo unit harness connector from the thermostat housing.
  16.  
  17. Remove the ground cable terminal from the right side of the common chamber, then remove the ground cable from the left front of the chamber.
  18.  
  19. Remove the starter and alternator cable clip.
  20.  
  21. Remove the 2 heater hoses from the engine, then remove the upper radiator hose.
  22.  
  23. Remove the throttle body heating hose from the coolant bypass pipe, then remove the pipe bracket from the cylinder head.
  24.  
  25. Disconnect the fuel feed and return lines.
  26.  
  27. Raise and support the vehicle safely, then remove the right side under cover. Disconnect the front exhaust pipe from the exhaust manifold, then remove the supports and carefully lower the vehicle.
  28.  
  29. Remove the right engine mount.
  30.  
  31. Remove the upper timing cover and the valve cover.
  32.  
  33. Remove the timing belt.
  34.  
  35. Remove the cylinder head bolts (remove the bolts from both ends at the same time, working toward the middle) and the cylinder head. Clean all of the mounting surfaces.
  36.  

To install:
  1. Clean the cylinder head gasket mounting surfaces, then install the cylinder head with a new gasket.
  2.  
  3. Tighten the bolts in at least 2 passes; first, torque the bolts to 29 ft. lbs. (40 Nm). The final torque should be 58 ft. lbs. (79 Nm).
  4.  
  5. Install the timing belt.
  6.  
  7. Install the valve cover and the upper timing cover.
  8.  
  9. Raise and support the vehicle safely, then install the right engine mount.
  10.  
  11. Connect the exhaust pipe to the exhaust manifold and install the right side under cover, then remove the supports and carefully lower the vehicle.
  12.  
  13. Connect the fuel feed and return lines.
  14.  
  15. Install the coolant bypass bracket to the cylinder head, then install the throttle body heating hose to the coolant bypass pipe.
  16.  
  17. Install the upper radiator hose, then connect the 2 heater hoses.
  18.  
  19. Install the starter and alternator harness cable clips to the common chamber.
  20.  
  21. Install the ground cable terminals to the right side and left front of the chamber.
  22.  
  23. Install the coolant temperature sensor and thermo unit harness connector to the thermostat housing.
  24.  
  25. Connect the ignition coil ground cable to the terminal on the thermostat housing flange.
  26.  
  27. Install the wiring harness to the oxygen sensor.
  28.  
  29. Install the EVAP canister pipe support bracket, then install the canister hoses to the pipes on the common chamber.
  30.  
  31. Connect the brake booster vacuum hose, then install the hose to the MAP sensor.
  32.  
  33. Connect the intake air duct to the throttle body, then install the PCV hose to the duct.
  34.  
  35. Connect the accelerator cable to the throttle body, then position the cable into the clips on the common chamber.
  36.  
  37. Connect the negative battery cable and fill the engine cooling system.
  38.  
  39. Start the engine and check for leaks.
  40.  

1.8L DOHC ENGINE

See Figure 2

  1. Relieve the fuel system pressure, then disconnect the battery negative cable.
  2.  
  3. Drain the engine cooling system.
  4.  
  5. Disconnect the accelerator cable from the throttle body and remove the retaining bracket.
  6.  
  7. Tag and disconnect all vacuum hoses from the valve cover.
  8.  
  9. Remove the upper timing belt cover.
  10.  
  11. Remove the valve cover.
  12.  
  13. Unplug the oxygen sensor electrical connector, then remove the heat shield from the exhaust manifold.
  14.  
  15. Raise and support the vehicle safely, then remove the right splash shield.
  16.  
  17. Remove the 3 nuts and the forward exhaust pipe from the exhaust manifold, then remove the supports and carefully lower the vehicle.
  18.  
  19. Remove the power steering pump and support the pump aside. If possible, do not disconnect the steering fluid lines in order to avoid having to fill and bleed the system during installation.
  20.  
  21. Remove the 2 bolts and the EGR pipe from the exhaust manifold, then remove the bolt from the EGR pipe bracket. Loosen the EGR pipe nuts, then disconnect the pipe from the EGR valve.
  22.  
  23. Tag and disconnect the vacuum lines from the EGR valve, then remove the EGR valve from the vehicle.
  24.  
  25. Remove the exhaust manifold from the cylinder head.
  26.  
  27. Remove the air intake duct from the throttle body.
  28.  
  29. Unplug the electrical connectors from the coolant temperature sensor and the thermo unit at the thermostat housing.
  30.  
  31. Tag and disconnect all vacuum hoses from the intake manifold.
  32.  
  33. Remove the throttle body from the common chamber.
  34.  
  35. Disconnect the brake booster vacuum hose.
  36.  
  37. Remove the common chamber from the intake manifold.
  38.  
  39. Unplug the fuel injector electrical connectors, then remove the 2 bolts and the engine wiring harness retainer.
  40.  
  41. Disconnect the fuel return hose from the fuel pressure regulator and the fuel pipe from the injector rail.
  42.  
  43. Unplug the electrical connector from the vacuum switching valve, then remove the valve from the bracket and the bracket from the engine.
  44.  
  45. Remove the coolant hose from the coolant pipe under the intake manifold.
  46.  
  47. Remove the intake manifold from the cylinder head.
  48.  
  49. Support the engine using a floor jack.
  50.  
  51. Remove the right engine mount, by first removing the through bolt, mount bracket bolt/nut and the engine mount. Then remove the center bolt and the serpentine drive belt from the tensioner mounting bracket. Finally, remove the 4 mount bridge retaining bolts and the bridge from the vehicle.
  52.  
  53. Remove the lower timing belt cover, then remove the timing belt from the vehicle.
  54.  
  55. Remove the cylinder head bolts (remove the bolts from both ends at the same time, working toward the middle) and the cylinder head. Clean all of the mounting surfaces.
  56.  

To install:
  1. Clean the cylinder head gasket mounting surfaces, then install the cylinder head with a new gasket.
  2.  
  3. Tighten the bolts in at least 2 passes; first, torque the bolts to 29 ft. lbs. (40 Nm). The final torque should be 58 ft. lbs. (79 Nm).
  4.  
  5. Install the timing belt.
  6.  
  7. Install the upper and lower timing belt covers.
  8.  
  9. Install the right engine mount bridge and tighten the retaining bolts to 30 ft. lbs. (40 Nm).
  10.  
  11. Install the serpentine drive belt tensioner to the mounting bracket and tighten the center bolt to 30 ft. lbs. (40 Nm).
  12.  
  13. Install the right engine mount to the vehicle. Tighten the through bolt to 50 ft. lbs. (68 Nm), then tighten the bracket nut/bolt to 30 ft. lbs. (40 Nm).
  14.  
  15. Remove the floor jack.
  16.  
  17. Install the intake manifold using a new gasket, tighten the retainers to 17 ft. lbs. (23 Nm).
  18.  
  19. Connect the coolant hose to the pipe under the intake manifold.
  20.  
  21. Install the vacuum switching and valve retaining bracket, then install the wiring harness connector to the valve.
  22.  
  23. Connect the fuel feed and return lines.
  24.  
  25. Install the common chamber to the intake manifold and tighten the retainers to 17 ft. lbs. (23 Nm).
  26.  
  27. Install the electrical harness retaining bolts.
  28.  
  29. Install the ground cable bolts to the common chamber and tighten to 71 inch lbs. (8 Nm).
  30.  
  31. Install the brake booster vacuum hose, then install the EGR valve.
  32.  
  33. Install the EGR vacuum hoses, then install the EGR pipe to the EGR valve and tighten the pipe nut to 11 ft. lbs. (15 Nm).
  34.  
  35. Install the throttle body to the common chamber and tighten the retainers to 17 ft. lbs. (23 Nm). Install the electrical connectors to the throttle body.
  36.  
  37. Install the vacuum hoses to the intake manifold.
  38.  
  39. Connect the air intake duct to the throttle body.
  40.  
  41. Install the exhaust manifold, using a new gasket, to the cylinder head. Tighten the retainers to 30 ft. lbs. (39 Nm).
  42.  
  43. Install the EGR pipe to the exhaust manifold, using a new gasket. Tighten the retaining bolts to 11 ft. lbs. (15 Nm).
  44.  
  45. Reposition and install the power steering pump assembly, then raise and support the vehicle safely.
  46.  
  47. Connect the exhaust pipe to the exhaust manifold. Tighten the retainers to 46 ft. lbs. (62 Nm). Install the right splash shield, then lower the vehicle.
  48.  
  49. Connect the heat shield to the manifold and tighten the retainers to 11 ft. lbs. (15 Nm). Install the wiring harness to the oxygen sensor.
  50.  
  51. Install the valve cover.
  52.  
  53. Connect the accelerator cable to the throttle valve.
  54.  
  55. Connect the negative battery cable and refill the engine cooling system, then start the engine and check for leaks.
  56.  



Click image to see an enlarged view

Fig. Fig. 2: Cylinder head bolt torque sequence - DOHC engines

CLEANING & INSPECTION



See Figure 3

  1. 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. Carbon deposits may be removed with the valves installed in order to protect the valve seats If the head is to the 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.
  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 damaged because a crack is not visually found. A fracture can be so small that it cannot be seen by eye, yet can still 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. 3: Remove carbon deposits from the cylinder head combustion chambers using a drill-mounted wire brush

RESURFACING



See Figures 4 and 5

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.  
  3. Place a precision straight edge diagonally across the gasket surfaces of the cylinder head as shown in Figs. 62 and 63. Using feeler gauges, determine the clearance at the center of the straight edge.
  4.  
  5. If warpage exceeds 0.0080 in. (0.2mm) along any axis, the head must be reground. If the warpage exceeds 0.0158 in. (0.4mm) along any axis, the cylinder head must be replaced.
  6.  



Click image to see an enlarged view

Fig. Fig. 4: Checking the cylinder head-to-block mating surface for warpage



Click image to see an enlarged view

Fig. Fig. 5: Check these cylinder head mating surfaces for warpage whenever the head is removed from then engine

 
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