Sierra, Silverado 2006-2007

Timing Chain & Sprockets

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Removal & Installation



4.3L Engine
  1. Drain the cooling system.
  2.  
  3. Remove or disconnect the following:

    Negative battery cable
     
    Timing chain cover and gaskets
     

  4.  
  5. Rotate the crankshaft until the timing marks on the camshaft and crankshaft sprockets are in proper alignment. This will put no. 4 cylinder at TDC.
  6.  
  7. Unsnap the timing chain tensioner shoe from the pin.
  8.  
  9. 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.



    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.

    Click image to see an enlarged view

    Fig. Timing mark alignment for timing chain removal and installation-4.3L engines

     

  10.  
  11. If necessary use J-5825-A, or equivalent, crankshaft sprocket removal tool to free the timing sprocket from the crankshaft.
  12.  
  13. Remove the crankshaft balancer key.
  14.  
  15. If necessary, remove the timing chain tensioner bracket bolt and bracket.
  16.  

To install:

  1. Inspect the timing chain and the timing sprockets for wear or damage, replace the damaged parts as necessary.
  2.  
  3. Clean the gasket mounting surfaces of all remaining traces of old gasket.
    NOTE
    During installation, coat the thrust surfaces lightly with Molykote® or equivalent pre-lube.

  4.  
  5. If necessary, install the timing chain tensioner bracket and bolt and tighten to 106 inch lbs. (12 Nm).
  6.  
  7. Install the key into the crankshaft keyway. The crankshaft balancer key should be parallel to the crankshaft or with a slight incline.
  8.  
  9. Install or connect the following:

    Crankshaft sprocket onto the crankshaft, use tool J-5590, crankshaft sprocket installation tool, and a hammer, without disturbing the position of the engine.
     
    Timing chain, 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.
     
    Cam sprocket, with the chain mounted under it in position on the front of the camshaft. Torque the camshaft sprocket-to-camshaft retainer bolts to 106 inch lbs. (12 Nm) on 5.0L and 5.7L, or 18 ft. lbs. (25 Nm) on 4.3L.
     

  10.  
  11. Install the timing chain tensioner shoe onto the bracket and position the top of the shoe under the tab at the top of the bracket.
  12.  
  13. With the timing chain installed, turn the crankshaft 2 complete revolutions, then check to make certain that the timing marks are in correct alignment between the shaft centers.

    Timing chain cover with a new seal
     
    Negative battery cable
     

  14.  
  15. Fill the cooling system with the proper type and quantity of antifreeze.
  16.  

4.8L, 5.3L, 6.0L & 6.2L Engines
  1. Drain the cooling system.
  2.  
  3. Remove or disconnect the following:

    Negative battery cable
     
    Front cover and gasket. Discard the front cover gasket.
     
    Oil pump
     

  4.  
  5. Rotate the crankshaft until the timing marks on the crankshaft and the camshaft sprockets are aligned.
    NOTE
    Do not turn the crankshaft assembly after the timing chain has been removed in order to prevent damage to the piston assemblies or the valves.

  6.  
  7. Remove or disconnect the following:

    Click image to see an enlarged view

    Fig. Sprocket and chain removal-4.8L, 5.3L, 6.0L and 6.2L engines



    Camshaft sprocket bolts
     
    Camshaft sprocket and timing chain
     
    Crankshaft sprocket
     
    Crankshaft sprocket key
     

  8.  

To install:

Click image to see an enlarged view

Fig. Crankshaft sprocket installation-4.8L, 5.3L, 6.0L and 6.2L engines

  1. Install or connect the following:

    Key into the crankshaft keyway
     
    Crankshaft sprocket onto the front of the crankshaft. Align the crankshaft key with the crankshaft sprocket keyway. Rotate the crankshaft sprocket until the alignment mark is in the 12 o'clock position.
     
    Camshaft sprocket and timing chain. Locate the camshaft sprocket alignment mark in the 6 o'clock position.
     
    Camshaft sprocket bolts and tighten to 26 ft. lbs. (35 Nm)

    Click image to see an enlarged view

    Fig. Timing mark alignment-4.8L, 5.3L, 6.0L and 6.2L engines

     

  2.  
  3. Install the oil pump and the front cover. Be sure to use a new gasket and oil seal.
  4.  

8.1L Engine

NOTE
This procedure requires the use of Crankshaft Sprocket Installer tool No. J 22102 and Crankshaft Protector Button tool No. J 42846.

  1. Drain the cooling system.
  2.  
  3. Remove or disconnect the following:

    Negative battery cable
     
    Front cover bolts, front cover and gasket
     

  4.  
  5. Align the timing marks on the camshaft and crankshaft sprockets.

    Camshaft sprocket bolts
     
    Camshaft sprocket and timing chain
     

  6.  
  7. Install Crankshaft Protector Button tool No. J 42846 into the end of the crankshaft and remove the crankshaft sprocket using a 3-jawed puller.
  8.  
  9. Clean and inspect the timing chain and sprockets.
  10.  

To install:

  1. Use the Crankshaft Sprocket Installer tool No. J 22102 to install the crankshaft sprocket. Align the keyway of the sprocket with the crankshaft pin.
  2.  
  3. Remove the installation tool.
  4.  
  5. Rotate the crankshaft until the crankshaft sprocket alignment mark is in the 12 o-clock position.
  6.  
  7. Install the camshaft sprocket and timing chain, noting the following important points:
    1. The cam sprocket must be installed with the alignment mark at the 6 o-clock position.
    2.  
    3. The sprocket teeth must mesh with the timing chain to avoid damaging the camshaft retainer.
    4.  
    5. Never use a hammer to install the sprocket onto the camshaft.
    6.  

  8.  
  9. Make sure the crankshaft sprocket is alignment at the 12 o-clock position and the cam sprocket is at the 6 o-clock position.
  10.  
  11. Install the camshaft sprocket bolts and tighten, in two passes, to 22 ft. lbs. (30 Nm)
  12.  
  13. Install the front cover.
  14.  
  15. Fill the cooling system with the proper type and quantity of antifreeze.
  16.  

 
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