Miata 1990-1997

Timing Belt Cover, Belt & Tensioner

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Removal & Installation



  1. Disconnect the negative battery cable. Drain the cooling system.
  2.  
  3. Remove the air intake pipe.
  4.  
  5. Remove the upper radiator hose and disconnect the coolant hoses at the thermostat housing.
  6.  
  7. Remove the accessory drive belts and the water pump pulley.
  8.  
  9. Remove the crankshaft pulley bolts and the crankshaft pulley. On 1992-97 vehicles, hold the pulley boss with a suitable tool and remove the pulley lock bolt. Remove the pulley boss.
  10.  
  11. On 1990-91 vehicles, remove the outer and inner timing belt guide plates.
  12.  
  13. Tag and disconnect the spark plug wires from the spark plugs. Remove the ignition coil and plug wires assembly. Remove the spark plugs.
  14.  
  15. Remove the cylinder head cover. Remove the upper, middle and lower timing belt covers.
  16.  
  17. On 1992-97 vehicles, temporarily reinstall the pulley boss and lock bolt.
  18.  
  19. Turn the crankshaft until the crankshaft and camshaft sprocket timing marks are aligned. On 1992-94 vehicles, the pin on the pulley boss must face upward.
  20.  
  21. On 1992-97 vehicles, remove the pulley boss and lock bolt, being careful not to disturb the crankshaft.
  22.  
  23. Mark the direction of rotation on the timing belt. Loosen the tensioner lock bolt and pry the tensioner outward. Tighten the lock bolt with the tensioner spring fully extended. Remove the timing belt.
    NOTE
    Protect the tensioner with a shop towel before prying on it. Do not rotate the crankshaft after the timing belt has been removed.

  24.  
  25. Remove the tensioner and spring. If necessary, remove the idler pulley.
  26.  
  27. Inspect the belt for wear, peeling, cracking, hardening or signs of oil contamination. Inspect the tensioner for free and smooth rotation. Check the tensioner spring free length; it should not exceed 2.315 in. (58.8mm). Inspect the sprocket teeth for wear or damage. Replace parts, as necessary.
  28.  

To install:

  1. If removed, install the idler pulley and tighten the bolt to 38 ft. lbs. (52 Nm).
  2.  
  3. Install the tensioner and tensioner spring. Pry the tensioner outward and temporarily tighten the tensioner lock bolt with the tensioner spring fully extended.
  4.  
  5. Make sure the crankshaft sprocket timing mark is aligned with the mark on the oil pump housing and the camshaft sprocket timing marks are aligned with the marks on the seal plate.
  6.  
  7. Install the timing belt so there is no looseness at the idler pulley side or between the camshaft sprockets. If reusing the old belt, make sure it is installed in the same direction of rotation.
  8.  
  9. On 1992-97 vehicles, temporarily install the pulley boss and lock bolt.
  10.  
  11. Turn the crankshaft 2 turns clockwise and align the crankshaft sprocket timing mark. On 1992-97 vehicles, face the pin on the pulley boss upright. Make sure the camshaft sprocket timing marks are aligned. If they are not, repeat Steps 16-20.
  12.  
  13. Turn the crankshaft 1 5 / 6 turns clockwise and align the crankshaft sprocket timing mark with the tension set mark for proper belt tension adjustment. On 1992-97 vehicles, remove the lock bolt and pulley boss.
  14.  
  15. Make sure the crankshaft sprocket timing mark is aligned with the tension set mark. Loosen the tensioner lock bolt and allow the spring to apply tension to the belt. Tighten the tensioner lock bolt to 38 ft. lbs. (52 Nm).
  16.  
  17. On 1992-97 vehicles, install the pulley boss and lock bolt.
  18.  
  19. Turn the crankshaft 2 1 / 6 turns clockwise and make sure the timing marks are correctly aligned.
  20.  
  21. Apply approximately 22 lbs. pressure to the timing belt at a point midway between the camshaft sprockets. The belt should deflect 0.35-0.45 in. (9.0-11.5mm). If the deflection is not correct, repeat Steps 22-25.
  22.  
  23. Install the timing belt covers and tighten the bolts to 95 inch lbs. (11 Nm).
  24.  
  25. Apply silicone sealer to the cylinder head in the area adjacent to the front and rear camshaft caps. Install the cylinder head cover and tighten the bolts to 78 inch lbs. (8.8 Nm).
  26.  
  27. Install the spark plugs. Install the ignition coil and tighten the bolts to 19 ft. lbs. (25 Nm). Connect the spark plug wires.
  28.  
  29. On 1990-91 vehicles, install the inner timing belt guide plate with the dished side facing away from the engine. Install the outer guide plate.
  30.  
  31. On 1992-97 vehicles, hold the pulley boss with a suitable tool and tighten the lock bolt to 123 ft. lbs. (167 Nm).
  32.  
  33. Install the crankshaft pulley. Tighten the bolts to 13 ft. lbs. (17 Nm).
  34.  
  35. Install the water pump pulley and the accessory drive belts. Adjust the belt tension.
  36.  
  37. Connect the coolant hoses to the thermostat housing and install the upper radiator hose.
  38.  
  39. Install the air intake pipe and connect the negative battery cable. Fill and bleed the cooling system.
  40.  
  41. Start the engine and bring to normal operating temperature. Check for leaks and proper operation. Check the ignition timing.

    Click image to see an enlarged view

    Fig. Crankshaft and camshaft sprocket timing mark alignment

  42.  

 
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