GM Bonneville/Eighty Eight/LeSabre 1986-1999

Balance Shaft

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REMOVAL & INSTALLATION



See Figures 1 and 2

For the removal of the camshaft or balance shaft, the engine assembly will probably need to be removed from the vehicle.

  1. Disconnect the negative battery cable. Remove the engine and secure it to a workstand.
  2.  
  3. Remove the flywheel-to-crankshaft bolts and remove the flywheel.
  4.  
  5. Remove the intake manifold.
  6.  
  7. Remove the lifter guide retainer.
  8.  
  9. Unfasten the timing chain cover-to-engine bolts, then remove the cover.
  10.  
  11. Remove the balancer shaft drive gear bolt.
  12.  
  13. Remove the camshaft sprocket and timing chain.
  14.  
  15. Remove the balance shaft retainer bolts, retainer and gear.
  16.  
  17. Using a suitable slide hammer tool, pull the balance shaft from the front of the engine.
  18.  
  19. Remove the balance shaft rear plug by driving it from the engine.
  20.  
  21. Remove the balance shaft rear bearing using a suitable bearing removal and installer tool to press the rear bearing from the engine.
  22.  

The balance shaft and both bearings are serviced as a complete package. You must use the proper tools when replacing the bearing and shaft.

  1. Inspect the balance shaft drive gear and the camshaft drive gear for nicks and burrs.
  2.  



Click image to see an enlarged view

Fig. Fig. 1: Balance shaft removal and installation

To install:
  1. Install the balance shaft gear bearing, as follows:
    1. Dip the new bearing in clean engine oil.
    2.  
    3. Using the balance shaft rear bearing installer tool, press the new rear bearing into the rear of the engine.
    4.  

  2.  
  3. Dip the front balance shaft into clean engine oil. Using the balance shaft installer tool, screw it into the balance shaft and install the shaft into the engine; remove the installer tool.
  4.  
  5. Temporarily install the balance shaft bearing retainer and bolts. Install the balance shaft drive gear. Apply a suitable sealer to the bolt threads, then install the bolt. Tighten the bolts to 14 ft. lbs. (20 Nm), plus an additional 35° rotation for 1987-92 vehicles. For 1993-99 vehicles, tighten the bolt to 16 ft. lbs. (22 Nm), plus an additional 70° rotation.
  6.  
  7. Install the rear cup plug.
  8.  
  9. Measure the balance shaft radial play at both the front and the rear. The end-play should be 0.00-0.008 in. (0-0.203mm).
  10.  



Click image to see an enlarged view

Fig. Fig. 2: You must measure the balance shaft clearances for proper specifications

  1. Measure the balance shaft radial play at both the front and the rear and compare with the following specifications:
    1. Front: 0-0.0011 (0-0.028mm).
    2.  
    3. Rear: 0.0005-0.0047 in. (0.127-0.119mm).
    4.  

  2.  
  3. Turn the camshaft so, with the camshaft sprocket temporarily installed, the timing mark is straight down.
  4.  
  5. With the camshaft sprocket and the camshaft gear removed, turn the balance shaft so that the timing mark on the gear points straight down.
  6.  
  7. Install the camshaft gear. Align the marks on the balance shaft gear and the camshaft gear by turning the balance shaft.
  8.  
  9. Turn the crankshaft so that the No. 1 piston is at Top Dead Center (TDC).
  10.  
  11. Install the timing chain and camshaft sprocket.
  12.  
  13. Measure the gear lash at four places, every 1 / 4 turn. The lash should be 0.002-0.005 in. (0.050-0.127mm).
  14.  
  15. Install the balance shaft front bearing retainer. Install the retainer bolts and tighten them to 22-26 ft. lbs. (30-35 Nm).
  16.  
  17. Install the front timing cover and the lifter guide retainer.
  18.  
  19. Install the intake manifold.
  20.  
  21. Install the flywheel assembly and tighten the bolts to the specifications given later in this section.
  22.  
  23. Install the engine assembly and connect the negative battery cable. Start the engine and check for leaks.
  24.  

 
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