Timing Chain, Sprockets, And TENSIONER (Unit Repair): Installation

1. Install timing chain drive sprocket to crankshaft with timing mark in the 5 o'clock position.
   Fig 1: Installing Timing Chain Drive Sprocket To Crankshaft

   Courtesy of GENERAL MOTORS CORP.

   IMPORTANT:  Always use new sprocket bolts.

2. Assemble intake camshaft sprocket to timing chain with timing mark lined up with the copper colored link. Finger-tighten a new intake camshaft sprocket bolt.
   Fig 2: Assembling Intake Camshaft Sprocket To Timing Chain

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3. Lower the timing chain through the opening in the cylinder head. Use care to make sure that the chain goes around both sides of the cylinder block bosses.
   Fig 3: Lowering Timing Chain Through The Opening In Cylinder Head

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4. Route timing chain around crankshaft sprocket and line up second silver link with timing mark on crankshaft sprocket in approximately the 5 o'clock position.
   Fig 4: Lining Up Second Silver Link With Timing Mark On Crankshaft Sprocket

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   NOTE: The camshaft bolt is a torque-to-yield (TTY) bolt, and must be discarded to prevent premature failure.
   NOTE: There is a 2nd design adjustable guide with a contact pad for the 2nd design notched tensioner. A 2nd design guide should be used only with a 2nd designed tensioner.
5. Install the adjustable timing chain guide through the opening in the cylinder head and install the adjustable timing chain bolt.

   Torque: 

   Timing Chain Guide (Adjustable) Bolt: 10 N.m (89 in-lbs) 

   Fig 5: Installing Adjustable Timing Chain Guide

   Courtesy of GENERAL MOTORS CORP.

   IMPORTANT:  Always install new sprocket bolts.

6. Install exhaust camshaft sprocket and a new bolt loosely onto the exhaust camshaft.
   Fig 6: Installing Exhaust Camshaft Sprocket

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7. Align timing mark on sprocket with silver link. Install bolt finger tight.
   Fig 7: Aligning Timing Mark On Sprocket With Silver Link

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   NOTE: Do not turn camshaft more than 1/2 turn in either direction. To do so may cause valve to piston contact. This may damage a valve and/or a piston. If camshaft is 180° out of time, use the following procedure to re-align cam.
8. Using a 24 mm wrench, first turn intake camshaft until alignment feature on back of camshaft sprocket seats in the notch in front of intake camshaft.
   1. 8.1 Turn crankshaft 45° in either direction.
   2. 8.2 Turn intake cam to appropriate location.
   3. 8.3 Turn crankshaft back to top dead center (TDC).
      Fig 8: Seating Camshaft Sprocket In Notch

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9. When sprocket seats on cam, tighten sprocket bolt finger tight.
   Fig 9: Seating Sprocket On Cam

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10. Verify that all colored links and appropriate timing marks are still aligned. If they are not, repeat portion of procedure necessary to align timing marks.
11. Install fixed timing chain guide.

    Torque: 

    Timing Chain Guide (Fixed) Bolts: 10 N.m (89 in-lbs) 

    Fig 10: Installing Fixed Timing Chain Guide

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12. Install upper timing chain guide.

    Torque: 

    Timing Chain Guide (Upper) Bolts: 10 N.m (89 in-lbs) 

    Fig 11: Installing Upper Timing Chain Guide

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13. Using a 24 mm wrench, engage the hex on intake camshaft and tighten camshaft sprocket bolt using a torque wrench.

    Torque: 

    Camshaft Sprocket Bolts: 85 N.m (63 ft-lbs) + 30° 

    NOTE: Do not turn camshaft more than 1/2 turn in either direction. To do so may cause valve to piston contact. This may damage a valve and/or a piston. If camshaft is 180° out of time, use the following procedure to re-align cam.
14. Using a 24 mm wrench, engage hex on exhaust camshaft. Using torque wrench, tighten camshaft sprocket bolt.

    Torque: 

    Camshaft Sprocket Bolts: 85 N.m (63 ft-lbs) + 30° 

    Fig 12: Engaging Hex On Exhaust Camshaft

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    NOTE: There is a 2nd design tensioner with a notch at the plunger end of the tensioner. this tensioner should be used only with the 2nd design adjustable guide.
15. Measure the timing chain tensioner assembly from end to end.

    A new tensioner should be supplied in the fully compressed non-active state. A tensioner in the compressed state will measure 72 mm (2.83 in.) (a) from end to end. A tensioner in the active state will measure 85 mm (3.35 in.) (a) from end to end. If the tensioner is not in the compressed state perform the following steps:

    1. 15.1 Hold a flat end of the tensioner piston with a wrench.
    2. 15.2 Rotate the piston clockwise by slightly less than one turn at which point resistance will be felt.
    3. 15.3 At this point the tensioner should measure 72 mm (2.83 in.) (a) from end to end. if the tensioner does not read 72 mm (2.83 in.) (a) from end to end, repeat steps 15.1 and 15.2.
       Fig 13: Measuring The Timing Chain Tensioner Assembly

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16. Check to see if all thread sealant is removed from the timing chain tensioner threaded hole in the cylinder head.
17. Install new sealing washer on timing chain tensioner.

    Torque: 

    Timing Chain Tensioner: 75 N.m (55 ft-lbs) 

18. The timing chain tensioner is released by compressing 2 mm (.079 in.) which will release the locking mechanism in the ratchet. The tensioner can be released by one of two methods:
    1. 18.1 If the engine has less than 48,279 km (30,000 mi.) the tensioner can be released by starting the engine. This method cannot be used on an engine with over 48,279 km (30,000 mi.) or the cam chain may jump teeth on the cam sprockets.
    1. 18.2 If the engine has over 48,279 km (30,000 mi.) on it use a suitable tool with a rubber tip on the end. Feed the tool down through the cam drive chant to rest on the cam chain. Then give a sharp jolt diagonally downwards to release the tensioner.
       Fig 14: Installing Timing Chain Tensioner

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19. Install timing chain oiling nozzle.

    Torque: 

    Timing Chain Oil Nozzle Bolt: 10 N.m (89 in-lbs) 

    Fig 15: Installing Timing Chain Oiling Nozzle

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20. Apply thread sealant P/N 12345382 compound to thread. Install timing chain guide bolt access hole plug.

Torque: 

Timing Chain Guide Bolt Access Hole Plug: 40 N.m (30 ft-lbs) 

Fig 16: Installing Timing Chain Guide Bolt Access Hole Plug

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