Chevrolet Cobalt Service & Repair Manual: Timing Chain, Replace

Caution: With the timing chain removed, avoid turning the camshaft or crankshaft. If movement is required, exercise extreme caution to avoid valve damage caused by piston contact.
1. Disconnect and isolate battery ground cable.
2. Raise and support vehicle with jack stands.
3. Remove front fender liner.
4. Turn drive belt tensioner clockwise.
5. Remove serpentine drive belt.
6. Remove crankshaft balancer bolt using harmonic balancer holder GM tool No. J-38122-A, or equivalent, to ensure crankshaft does not rotate while loosening mounting bolt.
7. Remove crankshaft balancer.
8. Remove engine front cover to water pump bolts, Fig. 1.
9. Remove remaining engine front cover mounting bolts.
10. Remove engine front cover gasket.
11. Loosen vent hose clamp at air cleaner resonator, air cleaner intake duct clamp at air cleaner outlet resonator.
12. Loosen air cleaner outlet resonator to throttle body clamp, located forward of accelerator cable bracket. Remove air cleaner resonator to accelerator bracket bolt.
13. Remove throttle body resonator, air cleaner intake duct and vent hose.
14. Disconnect accelerator and cruise control cables from throttle body, then the bracket.
15. Remove PCV valve.
16. Remove fuel line brackets and brake booster hose pipe from brackets.
17. Remove mounting screw, ignition coil and Ignition Control Module (ICM).
18. Remove ground strap.
19. Remove mounting bolts and camshaft cover.
20. Turn engine until crankshaft sprocket mark aligns with second silver link at five o'clock position.
21. Lower vehicle.
22. Ensure intake camshaft sprocket INT diamond is aligned with copper link at two o'clock position, Fig. 2.
23. Ensure exhaust camshaft sprocket EXH triangle is aligned with silver link at 10 o'clock position, Fig. 3.
24. Remove timing chain tensioner.
25. Remove fixed timing chain guide access plug.
26. Remove fixed timing chain guide, Fig. 4.
27. Remove upper timing chain guide, Fig. 5.
28. Remove exhaust camshaft sprocket bolt and camshaft sprocket using suitable 24 mm wrench to hold camshafts, Fig. 6.
29. Remove timing chain tensioner guide, Fig. 7.
30. Remove intake camshaft sprocket bolt, intake camshaft sprocket and timing chain through top of cylinder head, Fig. 8.
31. Remove crankshaft sprocket, balance shaft drive chain tensioner and adjustable balance shaft chain guide.
32. Remove small balance shaft drive chain guide.
33. Remove upper balance shaft drive chain guide, Fig. 9.
34. Remove balance shaft drive chain, Fig. 10.
35. Install upper balance shaft chain guide.
36. Install balance shaft drive chain with colored links lined up on marks on balance shaft drive sprockets and crankshaft sprocket, Fig. 11.
37. Place copper link so it aligns with intake side balance shaft sprocket timing mark.
38. Move clockwise around chain, place first chrome link inline with timing mark on crankshaft drive sprocket, five o'clock position.
39. Install chain on water pump drive sprocket.
40. Align last chrome link with timing mark on exhaust side balance shaft drive sprocket.
41. Install small balance shaft chain guide.
42. Tighten balance shaft chain guide bolts.
43. Install adjustable balance shaft drive chain guide.
44. Turn tensioner plunger 90° in its bore and compress plunger until paper clip can be inserted through hole in plunger body and into hole in tensioner plunger, Fig. 12.
45. Install timing chain tensioner.
46. Remove paper clip from balance shaft drive chain tensioner.
47. Install crankshaft sprocket with timing mark at five o'clock position, Fig. 13.
48. Lower timing chain through opening in top of cylinder head and ensure chain installs around both sides of cylinder block bosses.
49. Install intake camshaft sprocket with INT diamond at two o'clock position, Fig. 2.
50. Hand tighten new intake camshaft sprocket bolt.
51. Install timing chain around crankshaft sprocket with second silver link aligning with timing mark.
52. Install timing chain around intake camshaft sprocket with copper link aligning with INT diamond.
53. Install timing chain tensioner guide through opening in top of cylinder head.
54. Install exhaust camshaft sprocket with timing chain silver link at EXH triangle aligned ten o'clock position, Fig. 3.
55. Install suitable 24 mm wrench to rotate camshaft slightly, until exhaust sprocket aligns with camshaft.
56. Hand tighten new exhaust camshaft sprocket bolt.
57. Install fixed timing chain guide.
58. Apply sealant, GM part No. 12345382, or equivalent, compound to thread and install timing chain guide bolt access hole plug.
59. Install timing chain upper guide.
60. Measure timing chain tensioner when fully compressed; tensioner will measure 2.83 inches.
61. Install timing chain tensioner.
62. Install suitable rubber tipped tool, place tool down through camshaft drive to contact timing chain, release tensioner using sharp contact downwards.
63. Install suitable 24 mm wrench to hold camshaft, Fig. 14.
64. Torque mounting bolt to 63 ft. lbs., then tighten an additional 30° turn.
65. Install valve cover.
66. Raise and support vehicle with jack stands.
67. Install front engine cover.
68. Torque front cover bolts to 18 ft. lbs.
69. Torque crankshaft balancer bolt to 74 ft. lbs., then tighten bolt an additional 125° turn.
70. Lower vehicle.
71. Install accessory drive belt.
72. Inspect cooling system and fill to proper level with recommended coolant, as required.
73. Fill engine crankcase to proper level with recommended engine oil.
74. Connect battery ground cable.
75. Start engine and confirm proper operation, and ensure there are no leaks.
76. Clear DTC(s) using a suitably programmed scan tool.

Fig. 1 Engine front cover bolt replacement

Fig. 2 Timing chain copper link alignment

Fig. 3 Timing chain silver link alignment

Fig. 4 Fixed timing chain guide replacement

Fig. 5 Upper timing chain guide replacement

Fig. 6 Exhaust camshaft bolt & sprocket replacement

Fig. 7 Timing chain tensioner guide replacement

Fig. 8 Camshaft bolt, sprocket & timing chain replacement

Fig. 9 Upper balance shaft drive chain guide replacement

Fig. 10 Balance shaft drive chain replacement

Fig. 11 Timing chain installation

Fig. 12 Tensioner plunger & body installation

Fig. 13 Crankshaft sprocket timing mark

Fig. 14 Camshaft tightening

    Timing Chain Tensioner R & R
    1. Disconnect the negative battery cable. 2. Remove the camshaft cover. 3. Remove the timing chain tensioner, ...


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