Miata 1990-1997

Cylinder Head

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Removal & Installation





Click image to see an enlarged view

Fig. An exploded view of the cylinder head assembly.

  1. Properly relieve the fuel system pressure.
  2.  
  3. Disconnect the negative battery cable and drain the cooling system.
  4.  
  5. Remove the air cleaner and air flow meter assembly and the inlet air ducting. Disconnect the accelerator cable.
  6.  
  7. Disconnect the radiator and heater hoses.
  8.  
  9. Label and disconnect all necessary electrical connections and vacuum hoses. Disconnect the fuel lines.
  10.  
  11. Remove the ignition coil pack assembly with the spark plug wires.
  12.  
  13. Disconnect the exhaust pipe from the exhaust manifold and remove the exhaust manifold from the cylinder head.
  14.  
  15. Remove the cylinder head cover and the timing belt front covers.
  16.  
  17. Rotate the crankshaft, in the normal direction of rotation, until the No. 1 cylinder piston is at TDC on the compression stroke. Make sure the timing marks on the crankshaft and camshaft sprockets are properly aligned and mark the direction of rotation of the belt.
  18.  
  19. Loosen the timing belt tensioner lock bolt. Pry the tensioner outward with a prybar and tighten the lock bolt with the tensioner spring fully extended. Remove the timing belt.
  20.  
  21. Remove the intake manifold-to-engine block bracket.
  22.  
  23. When everything is disconnected, loosen the cylinder head bolts in the reverse of the tightening sequence in steps. Remove the bolts and lift the head off the engine.
  24.  
  25. If necessary, remove the intake manifold from the cylinder head.
  26.  

To install:

  1. Thoroughly, clean the cylinder head and the block contact surfaces. Examine the head gasket and check the cylinder head for cracks. Check the cylinder head for warpage using a feeler gauge and straightedge. The maximum allowable distortion is 0.006 in. (0.15mm).
  2.  
  3. If removed, install the intake manifold using a new gasket. Tighten the intake manifold bolts to 19 ft. lbs. (25 Nm).
  4.  
  5. Clean the cylinder head bolts and the threads in the block. Make sure the bolts turn freely in the block.
  6.  
  7. Install a new head gasket on the engine block. Make sure the camshaft sprocket timing marks are still aligned, as set during the removal procedure. Install the cylinder head.
  8.  
  9. Lubricate the bolt threads and seat surfaces with clean engine oil and install. Torque the bolts in 2-3 steps to 56-60 ft. lbs. (75-81 Nm) in the proper sequence.

    Click image to see an enlarged view

    Fig. The proper sequence to tighten the head bolts

  10.  
  11. Make sure the crankshaft and camshaft sprocket timing marks are aligned, install the timing belt and set the tension. Carefully rotate the crankshaft 2 turns to make sure the timing marks still line up. Install the timing belt covers.
  12.  
  13. Apply a thin bead of sealant to the cylinder head cover and install the new gasket. Install the cover and torque the cover bolts to 78 inch lbs. (9 Nm).
  14.  
  15. Using a new gasket, install the exhaust manifold and torque the nuts to 34 ft. lbs. (46 Nm). Install a new flange gasket and torque the nuts to 34 ft. lbs. (45 Nm).
  16.  
  17. Install the intake manifold-to-engine block bracket.
  18.  
  19. Install all cooling system hoses.
  20.  
  21. Install the ignition coil pack and spark plugs.
  22.  
  23. Connect all wiring and vacuum hoses. Connect the fuel lines.
  24.  
  25. Connect the accelerator cable. Install the air cleaner/air flow meter assembly and the air ducts.
  26.  
  27. Connect the negative battery cable. Fill and bleed the cooling system. Change the engine oil.
  28.  
  29. Start the engine and bring to normal operating temperature. Check for leaks. Check the ignition timing and idle speed.
  30.  

 
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