AMC Coupes/Sedans/Wagons 1975-1988 Repair Information

Timing Belt

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REMOVAL & INSTALLATION 4-121 Engine



See Figures 1 through 14

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Fig. Fig. 1: Do not bend, twist or turn the timing belt inside out. Never allow oil, water or steam to contact the belt



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Fig. Fig. 2: Check for premature parting of the belt



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Fig. Fig. 3: Check if the teeth are cracked or damaged



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Fig. Fig. 4: Inspect the timing belt for cracks, fraying, glazing or damage of any kind



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Fig. Fig. 5: Look for noticeable cracks or wear on the belt face



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Fig. Fig. 6: You may only have damage on one side of the belt; if so, the guide could be the culprit



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Fig. Fig. 7: Foreign materials can get in between the teeth and cause damage



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Fig. Fig. 8: Damage on only one side of the timing belt may indicate a faulty guide



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Fig. Fig. 9: ALWAYS replace the timing belt at the interval specified by the manufacturer



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Fig. Fig. 10: Align the camshaft timing mark with the edge of the cylinder head4-121 engine



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Fig. Fig. 11: Align the timing marks on the crankshaft and intermediate shaft4-121 engine



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Fig. Fig. 12: Exploded view of the timing belt and related components4-121 engine



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Fig. Fig. 13: Removing the camshaft pulley from the 4-121 engine



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Fig. Fig. 14: Sectional views of the different timing mark locations 4-121 engine

This engine used a toothed rubber belt to drive the camshaft. Belt tension is controlled by an adjustable idler pulley. The distributor is at the rear of the cylinder head and is driven by a gear pressed on the rear of the camshaft.


WARNING
Do not turn the engine backwards. Damage to the drive belt teeth could result. Turn the engine by the crankshaft bolt, not the camshaft.

  1. Rotate the crankshaft in the normal direction of rotation, until the timing mark on the pulley is pointing to the zero position on the degree scale on the block. The timing mark on the rear of the camshaft pulley should be aligned with the pointer on the cylinder head cover.
  2.  
  3. Loosen the accessory pulley attaching bolts. Remove the V belts and the cam drive belt shield.
  4.  
  5. Loosen the adjuster retaining screw to allow the belt to slacken and remove the belt.
  6.  
  7. To replace the belt, install the belt on the crankshaft pulley, and position it on the tensioner pulley. Slip the belt over the camshaft pulley using hand pressure only, while maintaining the pulleys at their respective timing marks.
  8.  

Do not pry the belt with metal tools. The belt drive surface can be damaged and premature belt failure can result.

  1. Turn the offset adjusting nut on the tensioning pulley counterclockwise to increase the belt tension. The belt is properly tensioned when the drive side of the belt can be twisted 90° with finger pressure.
  2.  

When checking belt tension, apply tension on the crankshaft with a wrench, in a counterclockwise direction, to get all the slack on one side of the belt.

  1. With pressure on the tensioning pulley nut, tighten the retaining nut to 29 ft. lbs. torque. Recheck the belt tension.
  2.  
  3. Install the drive belt shield. Install the alternator belts and adjust their tension. Tighten the accessory pulley bolts to 15 ft. lbs.
  4.  
  5. Start the engine and adjust the ignition timing.
  6.  

 
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