Isuzu Cars and Trucks 1981-1991

Diesel Engine Timing Sprockets

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REMOVAL AND INSTALLATION
Injection Pump Sprocket
  1. Disconnect the negative battery cable. Drain the cooling system.
  2.  


CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by the ethylene glycol antifreeze, and are quite likely to drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless it is contaminated or several years old.

  1. Remove the timing belt cover. Remove the injection pump sprocket flange.
  2.  
  3. Using a pry bar, remove the tension spring from the timing belt tensioner.
  4.  


NOTE
When removing the tension spring, avoid using excessive force for the spring may become distorted.

  1. Remove the tensioner pulley bolt and the pulley.
  2.  
  3. Remove the timing belt and discard it.
  4.  
  5. Using a 6mm, 1.25 pitch bolt, install the threaded portion into the threaded hole in the timing sprocket housing through the hole in the sprocket to prevent the sprocket from turning.
  6.  
  7. Remove the injection pump sprocket-to-shaft bolts.
  8.  
  9. Using a wheel puller, connect it to the injection pump sprocket and press it from the shaft.
  10.  



Click image to see an enlarged view

Fig. Injection pump sprocket diesel engine

To install:

  1. Install the injection pump sprocket by aligning it with the key groove and torque the bolt to 4252 ft. lbs. (5670 Nm)
  2.  
  3. Rotate the crankshaft to bring the No. 1 piston to TDC of the compression stroke.
  4.  
  5. Align the timing marks on the injection pump sprocket with the camshaft sprocket; the marks must be facing each other.
  6.  
  7. Using a new timing belt, install it in the following sequence: crankshaft sprocket, camshaft sprocket and the injection pump sprocket; the slack must be between the injection pump and camshaft sprockets.
  8.  
  9. Install the tension center and the tension pulley so the end of the tension center is fitted against both pins on the timing pulley housing.
  10.  
  11. Hand tighten the nut so the tension pulley can be rotated freely.
  12.  
  13. Install the tension spring and semi-tighten the pulley nut to 2236 ft. lbs. (3048 Nm).
  14.  
  15. Rotate the crankshaft 2 full turns clockwise to seat the belt and further turn the crankshaft 90and#x00B0; beyond TDC to settle the injection pump.
  16.  
  17. Loosen the tension pulley nut to take up the timing belt slack. Tighten the tension pulley nut to 79 and 1994 ft. lbs. (108 and 19130 Nm).
  18.  
  19. Install the injection pump sprocket flange; the hole in the outer circumference of the flange should be aligned with the triangular timing mark on the injection pump sprocket.
  20.  
  21. Rotate the crankshaft 2 full turns clockwise to bring the No. 1 piston to TDC of the compression stroke. Make sure the triangular timing mark on the timing sprocket is aligned with the hole in the flange, then, measure the timing belt tension; it should be 33 and 1955 lbs.
  22.  
  23. Install the timing belt cover.
  24.  
  25. To complete the installation, reverse the removal procedures.
  26.  
  27. Connect the negative battery cable. Refill the cooling system.
  28.  

Camshaft Sprocket
  1. Disconnect the negative battery cable.
  2.  
  3. Remove the timing belt cover. Remove the injection pump sprocket flange.
  4.  
  5. Using a pry bar, remove the tension spring from the timing belt tensioner.
  6.  


NOTE
When removing the tension spring, avoid using excessive force for the spring may become distorted.

  1. Remove the tensioner pulley bolt and the pulley.
  2.  
  3. Remove the timing belt and discard it.
  4.  
  5. Using a 6mm, 1.25 pitch bolt, install the threaded portion into the threaded hole in the camshaft sprocket housing through the hole in the sprocket to prevent the sprocket from turning.
  6.  
  7. Using a wheel puller, connect it to the camshaft sprocket and press it from the camshaft.
  8.  



Click image to see an enlarged view

Fig. Camshaft sprocket diesel engine

To install:

  1. Install the camshaft sprocket and torque the camshaft sprocket-to-camshaft bolt to 72 and 1987 ft. lbs. (96 and 19115 Nm).
  2.  
  3. Rotate the crankshaft to bring the No. 1 piston to TDC of the compression stroke.
  4.  
  5. Align the timing marks on the injection pump sprocket with the camshaft sprocket; the marks must be facing each other.
  6.  
  7. Using a new timing belt, install it in the following sequence: crankshaft sprocket, camshaft sprocket and the injection pump sprocket; the slack must be between the injection pump and camshaft sprockets.
  8.  
  9. Install the tension center and the tension pulley so the end of the tension center is fitted against both pins on the timing pulley housing.
  10.  
  11. Hand tighten the nut so the tension pulley can be rotated freely.
  12.  
  13. Install the tension spring and semi-tighten the pulley nut to 22 and 1936 ft. lbs. (29 and 1948 Nm).
  14.  
  15. Rotate the crankshaft 2 full turns clockwise to seat the belt and further turn the crankshaft 90and#x00B0; beyond TDC to settle the injection pump.
  16.  
  17. Loosen the tension pulley nut to take up the timing belt slack. Tighten the tension pulley nut to 79 and 1994 ft. lbs. (108 and 19130 Nm).
  18.  
  19. Install the injection pump sprocket flange; the hole in the outer circumference of the flange should be aligned with the triangular timing mark on the injection pump sprocket.
  20.  
  21. Rotate the crankshaft 2 full turns clockwise to bring the No. 1 piston to TDC of the compression stroke. Make sure the triangular timing mark on the timing sprocket is aligned with the hole in the flange, then, measure the timing belt tension; it should be 33 and 1955 lbs.
  22.  
  23. Install the timing belt cover.
  24.  
  25. To complete the installation, reverse the removal procedures.
  26.  
  27. Connect the negative battery cable. Refill the cooling system.
  28.  

Crankshaft Sprocket
  1. Disconnect the negative battery cable. Drain the cooling system.
  2.  


CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by the ethylene glycol antifreeze, and are quite likely to drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless it is contaminated or several years old.

  1. Remove the timing belt cover.
  2.  
  3. Using a pry bar, remove the tension spring from the timing belt tensioner.
  4.  


NOTE
When removing the tension spring, avoid using excessive force for the spring may become distorted.

  1. Remove the tensioner pulley bolt and the pulley.
  2.  
  3. Remove the timing belt and discard it.
  4.  
  5. Remove the crankshaft sprocket bolt.
  6.  


NOTE
To remove the crankshaft sprocket bolt, it may be necessary to remove the starter or the flywheel cover plate to lock the flywheel; otherwise, it may be difficult to keep the crankshaft from turning.

  1. Using a puller tool press the crankshaft center and timing sprocket from the crankshaft.
  2.  



Click image to see an enlarged view

Fig. Crankshaft sprocket diesel engine

To install:

  1. Install the crankshaft center and timing sprocket to the crankshaft and install the bolt.
  2.  
  3. Rotate the crankshaft to bring the No. 1 piston to TDC of the compression stroke.
  4.  
  5. Align the timing marks on the injection pump sprocket with the camshaft sprocket; the marks must be facing each other.
  6.  
  7. Using a new timing belt, install it in the following sequence: crankshaft sprocket, camshaft sprocket and the injection pump sprocket; the slack must be between the injection pump and camshaft sprockets.
  8.  
  9. Install the tension center and the tension pulley so the end of the tension center is fitted against both pins on the timing pulley housing.
  10.  
  11. Hand tighten the nut so the tension pulley can be rotated freely.
  12.  
  13. Install the tension spring and semi-tighten the pulley nut to 22 and 1936 ft. lbs. (28 and 1948 Nm).
  14.  
  15. Rotate the crankshaft 2 full turns clockwise to seat the belt and further turn the crankshaft 90and#x00B0; beyond TDC to settle the injection pump.
  16.  
  17. Loosen the tension pulley nut to take up the timing belt slack. Tighten the tension pulley nut to 79 and 1994 ft. lbs. (108 and 19130 Nm).
  18.  
  19. Install the injection pump sprocket flange; the hole in the outer circumference of the flange should be aligned with the triangular timing mark on the injection pump sprocket.
  20.  
  21. Rotate the crankshaft 2 full turns clockwise to bring the No. 1 piston to TDC of the compression stroke. Make sure the triangular timing mark on the timing sprocket is aligned with the hole in the flange, then, measure the timing belt tension; it should be 33 and 1955 lbs.
  22.  
  23. Install the timing belt cover.
  24.  
  25. To complete the installation, reverse the removal procedures.
  26.  
  27. Connect the negative battery cable. Refill the cooling system.
  28.  

 
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