GM Celebrity/Century/Ciera/6000 1982-1996 Repair Guide

Timing Chain and Sprocket

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REMOVAL & INSTALLATION



2.2L Engine

See Figure 1

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the timing chain front cover.
  4.  
  5. Rotate the crankshaft until the piston in No. 1 cylinder is at TDC on the compression stroke. The marks on the camshaft and crankshaft sprockets should be in alignment.
  6.  
  7. Loosen but do not remove, the timing chain tensioner nut.
  8.  
  9. Unbolt the camshaft sprocket bolt, then remove the sprocket and chain together. If the sprocket does not slide from the camshaft easily, a light blow with a soft mallet at the lower edge of the sprocket will dislodge it.
  10.  



Click image to see an enlarged view

Fig. Fig. 1: Timing chain assembly and timing mark alignment

  1. Use a puller such as J-22888 or equivalent and remove the crankshaft sprocket.
  2.  

To install:
  1. Install the crankshaft sprocket, using the installation tool J-5590 or equivalent.
  2.  
  3. Install the timing chain over the camshaft sprocket and then around the crankshaft sprocket. Make sure the marks on the two sprockets are in alignment.
  4.  
  5. Lubricate the thrust surface with Molykote® or it's equivalent.
  6.  
  7. Align the dowel in the camshaft with the dowel hole in the sprocket and then install the sprocket onto the camshaft. Use the mounting bolt to draw the sprocket onto the camshaft and then tighten to 77 ft. lbs. (105 Nm).
  8.  
  9. Lubricate the timing chain with clean engine oil. Tighten the bolts on the chain tensioner to 18 ft. lbs. (24 Nm).
  10.  
  11. Install the timing chain front cover.
  12.  
  13. Connect the negative battery cable.
  14.  

2.5L Engine

See Figure 2

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the crankcase front cover.
  4.  
  5. Loosen the camshaft bolt.
  6.  
  7. Place the No. 1 piston at TDC with the marks on the camshaft and crankshaft sprockets aligned.
  8.  



Click image to see an enlarged view

Fig. Fig. 2: Exploded view of the 2.5L timing chain and marks

  1. Remove the camshaft sprocket and chain.
  2.  

If the sprocket does not come off easily, a light blow with a plastic mallet on the lower edge of the sprocket should dislodge the sprocket.

To install:
  1. Aligning the timing marks with the engine at TDC, install the timing chain and sprocket.
  2.  
  3. Insert and tighten the camshaft bolt to 43 ft. lbs. (58 Nm).
  4.  
  5. Lubricate the timing chain with engine oil. Install the crankcase front cover. Connect battery negative cable.
  6.  

2.8L Engine
  1. Relieve the pressure in the fuel system before disconnecting any fuel line connections. Disconnect the negative battery cable.
  2.  
  3. Remove the crankcase front cover.
  4.  
  5. Place the No. 1 piston at TDC with the marks on the camshaft and crankshaft sprockets aligned.
  6.  
  7. Remove the camshaft sprocket and chain.
  8.  

If the sprocket does not come off easily, a light blow with a plastic mallet on the lower edge of the sprocket should dislodge the sprocket.

  1. Remove the crankshaft sprocket.
  2.  

To install:
  1. Install the crankshaft sprocket. Apply Molykote® or equivalent, to the sprocket thrust surface.
  2.  
  3. Hold the sprocket with the chain hanging down and align the marks on the camshaft and crankshaft sprockets.
  4.  
  5. Align the dowel in the camshaft with the dowel hole in the camshaft sprocket.
  6.  
  7. Draw the camshaft sprocket onto the camshaft using the mounting bolts. Tighten the camshaft sprocket mounting bolts to 18 ft. lbs. (25 Nm).
  8.  
  9. Lubricate the timing chain with engine oil. Install the crankcase front cover. Connect battery negative cable.
  10.  

3.0L Engine

See Figures 3 and 4

  1. Remove the timing chain cover.
  2.  
  3. Turn the crankshaft so that the timing marks are aligned.
  4.  
  5. Remove the crankshaft oil slinger.
  6.  



Click image to see an enlarged view

Fig. Fig. 3: Exploded view of the 3.0L and 3.8L timing chain



Click image to see an enlarged view

Fig. Fig. 4: Timing marks for the 3.0L and 3.8L timing chain

  1. Remove the camshaft sprocket bolts.
  2.  
  3. Use two prybars to alternately pry the camshaft and crankshaft sprocket free along with the chain.
  4.  
  5. Installation is the reverse of removal. If the engine was turned, make sure that the No. 1 cylinder is at TDC.
  6.  

3.1L Engine (VIN M)

See Figure 5

  1. Disconnect the negative battery cable.
  2.  
  3. Drain the cooling system into a suitable container.
  4.  
  5. Remove the timing chain front cover.
  6.  
  7. Rotate the crankshaft until the timing marks on the camshaft and crankshaft sprockets are in alignment at their closest approach.
  8.  
  9. Remove the camshaft sprocket mounting bolt and remove the camshaft sprocket and timing chain.
  10.  
  11. Remove the crankshaft sprocket with a gear puller, J-5825-A, or the equivalent.
  12.  
  13. Remove the two bolts and remove the timing chain damper.
  14.  



Click image to see an enlarged view

Fig. Fig. 5: The 3.1L (VIN M) engine exploded view of the timing chain

To install:
  1. Install the timing chain damper and tighten the mounting bolts to 15 ft. lbs. (21 Nm).
  2.  
  3. Install the crankshaft sprocket onto the crankshaft making sure the notch in the sprocket fits over the crankshaft key. Fully seat the sprocket on the crankshaft using J-38612, or an equivalent gear installer.
  4.  
  5. Make sure the timing mark on the crankshaft sprocket is still pointing straight up.
  6.  
  7. Install the camshaft sprocket inside the timing chain.
  8.  
  9. Pick up the chain and sprocket and hold the sprocket in such a way that the timing mark is pointing down and the timing chain is hanging down off of the sprocket.
  10.  
  11. Loop the timing chain under the crankshaft sprocket and install the camshaft sprocket on the camshaft. The sprocket will only fit on the camshaft if the dowel on the camshaft lines up with the hole in the sprocket.
  12.  
  13. Verify the timing marks are aligned. If the marks are not in alignment proceed as follows:
    1. Remove the chain and sprocket.
    2.  
    3. Install the sprocket and mounting bolt loosely.
    4.  
    5. Rotate the crankshaft and camshaft until the marks are in alignment.
    6.  
    7. Remove the camshaft sprocket and mounting bolt.
    8.  

  14.  
  15. Repeat steps 13 and 14.
  16.  
  17. Tighten the camshaft sprocket mounting bolt to 74 ft. lbs. (100 Nm).
  18.  
  19. Lubricate the timing chain components with engine oil.
  20.  
  21. Install the timing chain front cover.
  22.  
  23. Refill the cooling system.
  24.  
  25. Connect the negative battery cable.
  26.  
  27. Start the vehicle and verify no leaks.
  28.  

3.1L Engine (VIN T)

See Figure 6

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the crankcase front cover.
  4.  
  5. Place the No. 1 piston at TDC with the marks on the camshaft and crankshaft sprockets aligned.
  6.  
  7. Remove the camshaft sprocket and chain.
  8.  



Click image to see an enlarged view

Fig. Fig. 6: View of the 3.1L (VIN T) timing chain marks

If the sprocket does not come off easily, a light blow with a plastic mallet on the lower edge of the sprocket should dislodge the sprocket.

  1. Remove the crankshaft sprocket.
  2.  

To install:
  1. Install the crankshaft sprocket. Apply Molykote® or equivalent, to the sprocket thrust surface.
  2.  
  3. Hold the sprocket with the chain hanging down and align the marks on the camshaft and crankshaft sprockets.
  4.  
  5. Align the dowel in the camshaft with the dowel hole in the camshaft sprocket.
  6.  
  7. Draw the camshaft sprocket onto the camshaft using the mounting bolts. Tighten the camshaft sprocket mounting bolts to 18 ft. lbs. (25 Nm).
  8.  
  9. Lubricate the timing chain with engine oil. Install the crankcase front cover. Connect battery negative cable.
  10.  

3.3L Engine

See Figure 7

  1. Relieve the pressure in the fuel system before disconnecting any fuel line connections.
  2.  
  3. Disconnect the negative battery cable.
  4.  
  5. Remove the crankcase front cover and camshaft thrust bearing.
  6.  
  7. Turn the crankshaft so the timing marks are aligned.
  8.  
  9. Remove the timing chain damper and camshaft sprocket bolts.
  10.  



Click image to see an enlarged view

Fig. Fig. 7: Exploded view of the 3.3L timing chain and timing marks

  1. Remove the camshaft sprocket and chain. Remove the crankshaft sprocket.
  2.  

To install:
  1. Make sure the crankshaft is positioned so No. 1 piston is at TDC on compression stroke.
  2.  
  3. Rotate the camshaft with the sprocket temporarily installed, so the timing mark is straight down.
  4.  
  5. Assembly the timing chain on the sprockets with the timing marks aligned. Install the timing chain and sprocket.
  6.  
  7. Install the camshaft sprocket bolts. Tighten the bolts to 27 ft. lbs. (37 Nm).
  8.  
  9. Install the timing chain damper and engine front cover. Connect battery negative cable.
  10.  

3.8L Engine

See Figures 3 and 4

  1. Relieve the pressure in the fuel system before disconnecting any fuel line connections.
  2.  
  3. Disconnect the negative battery cable.
  4.  
  5. Remove the crankcase front cover.
  6.  
  7. Turn the crankshaft so the timing marks are aligned.
  8.  
  9. Remove the crankshaft oil slinger, as required.
  10.  
  11. Remove the camshaft sprocket bolts.
  12.  
  13. Remove the cam sensor magnet assembly.
  14.  
  15. Use 2 prybars to alternately pry the camshaft and crankshaft sprocket free along with the chain.
  16.  

To install:
  1. Make sure the crankshaft is positioned so No. 1 piston is at TDC.
  2.  
  3. Rotate the camshaft with the sprocket temporarily installed, so the timing mark is straight down.
  4.  
  5. Assemble the timing chain on the sprockets with the timing marks aligned. Install the timing chain and sprocket.
  6.  
  7. Install the cam sensor magnet assembly.
  8.  
  9. Install the oil slinger with the large part of the cone toward the front of the engine, as required.
  10.  
  11. Secure the camshaft sprocket bolt, thrust button and spring.
  12.  
  13. Attach the timing chain damper and engine front cover.
  14.  

4.3L Diesel Engine

The following procedure requires the bleed-down of the valve lifters. Read that procedure before proceeding.

  1. Remove the front cover.
  2.  
  3. Loosen all the rocker arms.
  4.  
  5. Remove the crankshaft oil slinger.
  6.  
  7. Remove the camshaft sprocket-to-camshaft bolt and washer.
  8.  
  9. Using two prybars, work the camshaft and crankshaft sprockets alternately off their shafts along with the chain. It may be necessary to remove the crankshaft sprocket with a puller.
  10.  

To install:
  1. If the camshaft sprocket to cam key should come out with the camshaft sprocket, remove the front camshaft bearing retainer and install the key into the injection pump drive gear. Install the bearing retainer and tighten the bolts to 48 ft. lbs. (65 Nm).
  2.  
  3. Install the key in the crankshaft, if removed.
  4.  
  5. Install the camshaft sprocket, crankshaft sprocket and timing chain together, then align the marks.
  6.  
  7. Tighten the camshaft sprocket bolt to 64 ft. lbs. (87 Nm).
  8.  
  9. Install the oil slinger.
  10.  
  11. After installing the front cover, you will need to bleed down the valve lifters. See the procedure in this section.
  12.  
  13. Install the valve covers, then check and reset the injection pump timing.
  14.  
  15. Road test and check for leaks.
  16.  

 
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