Friday, October 14, 2011

How to replace camshaft Bearings and Lifters on 2006 Chevrolet Cobalt?


Bearing Replacement



Check each bearing for damage. If the bearing surface is excessively damaged, replace the cylinder head assembly or camshaft bearing cap, as necessary.

Inspection



  1. Clean the camshafts with cleaning solvent.
  2. Inspect the camshafts for scored journals, damaged lobes, damaged sprocket locator slots, and damaged threads.
  3. Check the camshaft bearing journals for damage and binding.
  4. If the journals are binding, check the cylinder head for damage.
  5. Check the cylinder head for clogged oil passages.
  6. Check the camshaft surface for abnormal wear and damage. Replace the camshaft, as required.
  7. Measure the camshaft lobe surface and replace the camshaft if not within specification.
  8. Measure the camshaft journal diameter and replace the camshaft if not within specification.
  9. Measure the camshaft run out and replace the camshaft if not within specification.
  10. Inspect the valve lash adjusters for excessive wear, clogged oil passages, damage, or collapsing and sponginess.

Removal & Installation



2.0L, 2.2L, & 2.4L Engines
  1. Before servicing the vehicle, refer to the Precautions Section.
  2. Remove the camshaft cover. Refer to Camshaft Covers removal and installation.

    Click image to see an enlarged view
    Fig. Remove the upper timing chain guide
  3. Remove the upper timing chain guide. Install camshaft sprocket holding tool J 43655, or equivalent.

    Click image to see an enlarged view
    Fig. Camshaft sprocket holding tool J 43655 installed
  4. Remove both the intake and exhaust camshaft sprocket bolts and discard.
  5. Slide the camshaft sprockets forward.
  6. Mark the caps to ensure they are installed in the original position.
    NOTE
    Remove each bolt on each cap one turn at a time until there is no spring tension on the camshaft.
  7. Remove the caps.
  8. Remove the camshaft.
  9. Remove the camshaft roller followers.

    Click image to see an enlarged view
    Fig. Removing the camshaft roller followers
  10. Remove the hydraulic lash adjusters.

    Click image to see an enlarged view
    Fig. Removing the hydraulic lash adjusters
To install:
  1. Lubricate the valve tips.
  2. Install the hydraulic lash adjusters.
  3. Install the camshaft roller followers.

    Click image to see an enlarged view
    Fig. Ensure that the alignment notches are aligned with the camshaft sprocket
  4. Ensure that the alignment notches are aligned with the camshaft sprocket.
  5. Install the camshaft.
  6. Install the caps.
  7. Tighten the camshaft bearing cap bolts in increments of 3 turns until they are seated. Tighten the camshaft bearing cap bolts to 89 inch lbs. (10 Nm).

    Click image to see an enlarged view
    Fig. Apply a 3.5mm (0.138 inch) bead of GM P/N 12378521 (Canadian P/N 88901148) to the rear cap
  8. Apply a 3.5mm (0.138 in) bead of GM P/N 12378521 (Canadian P/N 88901148) to the rear cap.
  9. Install the rear intake camshaft bearing cap bolts. Tighten the bolts to 18 ft. lbs. (25 Nm).
  10. Install camshaft sprockets onto the camshafts.
  11. Hand tighten NEW camshaft sprocket bolts.
  12. Remove the camshaft sprocket holding tool J 43655.
  13. Tighten the camshaft sprocket bolts. Tighten the bolts to 63 ft. lbs. (85 Nm) plus 30°.
  14. Install the upper timing chain guide. Tighten the upper timing chain guide to 89 inch lbs. (10 Nm).
  15. Install the camshaft cover and bolts. Refer to Camshaft Covers removal and installation.

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Camshaft, Bearings & Lifters




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