S&T Series Blazer, Bravada, Envoy, Jimmy, Rainier, Trailblazer, Xtreme

Timing Chain Cover & Seal

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Removal & Installation



4.2L Engine
  1. Before servicing the vehicle, refer to the Precautions section.
  2.  
  3. Remove or disconnect the following:
    WARNING
    When removing the seal, be careful not to damage the front cover or crankshaft.



    Negative battery cable
     
    Drain the engine cooling system.
     
    Cooling fan and shroud
     
    Accessory belt
     
    Water pump
     
    Crankshaft balancer
     



    Seal from the front cover, using a suitable prytool in the slots provided
     
    Power steering pump
     

  4.  
  5. Raise and safely support the vehicle.

    Oil pan, then carefully lower the vehicle
     
    7mm center bolt
     
    Remaining front cover bolts. Place two of the front cover bolts in the jackscrew holes on the front cover and tighten the bolts evenly to release the front cover from the engine.

    Click image to see an enlarged view

    Fig. Place 2 front cover bolts in the jackscrew holes on the cover and tighten to push the cover off of the engine

     
    2 bolts from the front cover
     
    Oil pump
     

  6.  

To install:

  1. Clean the gasket mating surfaces of the engine and cover of all remaining gasket or sealer material. Be careful not to score or damage the surfaces.
  2.  
  3. Install or connect the following:
    NOTE
    The front cover MUST be installed within 10 minutes of applying the sealant.



    Suitable cover alignment pins, onto the engine
     



    Apply a 0.12 in. (3mm) beat of 12378521 or equivalent sealant to the trace grooves on the back side of the engine front cover. Apply sealant on the inside 3 bolt hole bosses on the cover also.
     
    Oil pump to the crankshaft splines
     
    Front cover and bolts, tighten the center bolt last. Tighten to 89 inch lbs. (10 Nm).
     

  4.  
  5. Remove the alignment pins and raise and safely support the vehicle. Install the oil pan, then lower the vehicle.

    Power steering pump
     
    Crankshaft balancer
     
    Water pump
     
    Accessory belt
     
    Cooling fan and shroud
     
    Negative battery cable
     

  6.  
  7. Properly refill the engine cooling system.
  8.  
  9. Run the engine until normal operating temperature has been reached, then check for leaks.
  10.  

4.3L Engine
  1. Before servicing the vehicle, refer to the Precautions section.
  2.  
  3. Remove or disconnect the following:

    Negative battery cable
     

  4.  
  5. Drain the engine cooling system.
    WARNING
    The outer ring (weight) of the torsional damper is bonded to the hub with rubber. The damper must be removed with a puller which acts on the inner hub only. Pulling on the outer portion of the damper will break the rubber bond or destroy the tuning of the unit.



    Crankshaft pulley and damper
     



    Water pump assembly
     
    Oil pan, loosen only
     
    Crankshaft Position (CKP) sensor, if equipped
     
    Front cover bolts and the reinforcements, if equipped
     
    Front cover from the engine
     

  6.  
  7. Pry the seal out of the front cover using a small prytool. Be very careful not to distort the front cover or to score the end of the crankshaft.
  8.  

To install:


NOTE
Anytime the front cover is removed, the cover must be replaced upon reassembly. If you reuse the old cover, oil leaks may develop.

  1. Clean the gasket mating surfaces of the engine and cover of all remaining gasket or sealer material. Be careful not to score or damage the surfaces.
    NOTE
    The manufacturer suggests you wait until the front cover is mounted to the engine before you install the replacement crankshaft oil seal. This assures the cover is properly supported.

  2.  
  3. Install or connect the following:

    New front cover gasket to the engine or cover using gasket cement to hold it in position. Lubricate the front of the oil pan seal with engine oil to aid in reassembly.
     
    Front cover to the engine. Take care while engaging the front of the oil pan seal with the bottom of the cover. On 2001 models, apply sealer 12346141 to the oil pan rail where it contacts the timing cover-to-block joint (front) and the crankshaft rear seal retainer-to-block joint (rear). Continue the bead of sealant about 1 in. (25mm) in both directions from each of the four corners.
     
    Front cover retaining bolts and tighten to 106 inch. lbs. (12 Nm)
     

  4.  
  5. Lightly coat the lips of the replacement crankshaft seal with clean engine oil, then position the seal with the open end facing inward the engine. Use a suitable seal installation driver to position the seal in the front cover.

    CKP sensor O-ring and the sensor, if equipped
     
    Tighten the oil pan bolts
     
    Water pump
     
    Crankshaft damper and pulley
     
    Negative battery cable
     

  6.  
  7. Properly refill the engine cooling system.
  8.  
  9. Run the engine until normal operating temperature has been reached, then check for leaks.

    Click image to see an enlarged view

    Fig. Installing the crankshaft front oil seal-4.3L engine

  10.  

5.3L Engine
  1. Before servicing the vehicle, refer to the Precautions section.
  2.  
  3. Properly discharge the A/C system.
  4.  
  5. Drain the engine cooling system.
  6.  
  7. Remove or disconnect the following:

    Negative battery cable
     
    A/C compressor and bracket
     
    Water pump
     
    Crankshaft balancer
     
    Oil pan-to-front cover bolts
     
    Front cover bolts
     
    Front cover and gasket. Discard the gasket.
     

  8.  
  9. Clean and inspect the front cover.
  10.  

To install:

  1. Apply a 0.20 in. (5mm) bead of sealant 0.80 in. (20mm) long to the oil pan-to-engine block junction.
  2.  
  3. Install or connect the following:

    New front cover gasket and cover
     
    Front cover bolts, finger-tight
     
    Oil pan-to-front cover bolts, finger-tight
     
    Front and Rear Cover Alignment Tool No. J 41476 to the front cover. Align the tapered legs of the tool with the machined alignment surfaces on the front cover

    Click image to see an enlarged view

    Fig. Align the tapered legs of the tool with the machined alignment surfaces on the front cover-5.3L engine

     
    Crankshaft balancer bolt, finger-tight
     
    Oil pan-to-front cover bolts to 18 ft. lbs. (25 Nm)
     
    Front cover bolts to 18 ft. lbs. (25 Nm)
     

  4.  
  5. Remove the tool.
  6.  
  7. Install a NEW crankshaft front oil seal as follows:
    1. Remove the radiator for access.
    2.  
    3. Remove the crankshaft balancer.
    4.  
    5. Remove the crankshaft oil seal.
    6.  
    7. Lubricate the outer edge ONLY of the NEW crankshaft oil seal with clean engine oil.
    8.  
    9. Install the crankshaft front oil seal into the Crankshaft Front Seal Installation Tool No. J 41478 guide.
    10.  
    11. Install the J 41478 threaded rod (with nut, washer, guide and oil seal) into the end of the crankshaft.
    12.  
    13. Use J 41478 to install the oil seal into the cover bore. Use a wrench and hold the hex on the installer bolt. Use a second wrench to rotate the installer nut clockwise until the seal bottoms in the cover bore. Remove the tool.

      Click image to see an enlarged view

      Fig. Front cover seal installation using the proper tool-5.3L engine

    14.  
    15. Check the seal for proper installation. It should be installed evenly and completely into the front cover bore.
    16.  
    17. Install the crankshaft balancer. Tighten the bolt to 37 ft. lbs. (50 Nm), plus an additional 140 degrees using a torque angle meter.
    18.  
    19. Install the radiator.
    20.  

  8.  
  9. Install or connect the following:

    Water pump
     
    A/C compressor and bracket
     
    Cooling system with coolant
     
    Negative battery cable
     

  10.  
  11. Properly recharge the A/C system
  12.  

 
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