S10 Pickup, Sonoma 2000-2004

Timing Chain & Sprockets

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Removal & Installation



2.2L Engines
  1. Remove or disconnect the following:

    Negative battery cable
     
    Crankcase (timing) front cover from the engine
     

  2.  
  3. Turn the crankshaft until the timing marks on the sprockets are in alignment. The marks should also be in alignment with the tabs on the tensioner.

    Tensioner retaining bolts

    Click image to see an enlarged view

    Fig. Timing chain, sprocket and camshaft alignment marks-2.2L engine



    Click image to see an enlarged view

    Fig. Locking the timing chain tensioner into position for chain installation-2.2L engine

     
    Camshaft sprocket retaining bolts
     
    Camshaft sprocket and timing chain at the same time
     
    Tensioner assembly
     
    Crankshaft Position (CKP) sensor, if equipped
     
    Crankshaft sprocket using J-22888-20, if equipped
     

  4.  

To install:

  1. Install or connect the following:

    Crankshaft sprocket using a suitable installer such as J-5590, if removed. Make sure the sprocket is fully seated against the crankshaft.
     

  2.  
  3. Compress the tensioner spring and insert a cotter pin or nail in the hole provided to hold the tensioner in position.

    Tensioner retaining bolts
     
    Camshaft sprocket in the timing chain, position the chain under the crankshaft sprocket and the camshaft sprocket to the camshaft
     

  4.  
  5. Verify that the timing marks are all properly aligned, then loosely install the camshaft sprocket bolt.

    CKP sensor, if equipped
     
    Tighten the tensioner bolts to 18 ft. lbs. (24 Nm), then tighten the camshaft sprocket bolt to 96 ft. lbs. (130 Nm)
     

  6.  
  7. Remove the cotter pin or nail holding the tensioner in position off the chain.

    Timing cover to the engine
     

  8.  

4.3L Engine

NOTE
The following procedure requires the use of the Crankshaft Sprocket Removal tool No. J-5825-A and the Crankshaft Sprocket Installation tool No. J-5590.

  1. Remove the timing cover from the engine.
  2.  
  3. If equipped, remove the crankshaft reluctor ring.
  4.  
  5. Rotate the crankshaft until the No. 4 cylinder is on the Top Dead Center (TDC) of its compression stroke and the camshaft sprocket mark aligns with the mark on the crankshaft sprocket (facing each other at a point closest together in their travel) and in line with the shaft centers.
  6.  
  7. Remove or disconnect the following:
    NOTE
    The camshaft sprocket (located by a dowel) is lightly pressed onto the camshaft and should come off easily. The chain comes off with the camshaft sprocket.



    Crankshaft Position (CKP) sensor reluctor ring, if equipped

    Click image to see an enlarged view

    Fig. Timing mark alignment-4.3L engine

     
    Camshaft sprocket-to-camshaft nut and/or bolts
     
    Camshaft sprocket (along with the timing chain). If the sprocket is difficult to remove, use a plastic mallet to bump the sprocket from the camshaft.
     

  8.  
  9. If necessary use J-5825-A crankshaft sprocket removal tool to free the timing sprocket from the crankshaft.
  10.  
  11. If necessary, remove the crankshaft sprocket key.
  12.  

To install:

  1. Inspect the timing chain and the timing sprockets for wear or damage, replace the damaged parts as necessary.

    Click image to see an enlarged view

    Fig. Removal (top) and installation of the crankshaft timing gear

  2.  
  3. Using a putty knife, clean the gasket mounting surfaces. Using solvent, clean the oil and grease from the gasket mounting surfaces.
  4.  
  5. Install or connect the following:
    NOTE
    During installation, coat the thrust surfaces lightly with Molykote® or an equivalent pre-lube.



    Crankshaft sprocket key, if removed
     
    Crankshaft sprocket onto the crankshaft using J-5590 crankshaft sprocket installation tool and a hammer without disturbing the position of the engine
     



    Timing chain over the camshaft sprocket. Arrange the camshaft sprocket in such a way that the timing marks will align between the shaft centers and the camshaft locating dowel will enter the dowel hole in the cam sprocket.
     
    Timing chain under the crankshaft sprocket, then place the cam sprocket, with the chain still mounted over it, in position on the front of the camshaft
     
    Camshaft sprocket-to-camshaft retainers to 18 ft. lbs. (25 Nm)
     

  6.  
  7. With the timing chain installed, turn the crankshaft two complete revolutions, then check to make certain that the timing marks are in correct alignment between the shaft centers.

    CKP sensor reluctor ring, if equipped
     
    Timing cover
     

  8.  

 
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