Saturn Coupes/Sedans/Wagons 1991-1998 Repair Guide

Timing Chain and Sprockets

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REMOVAL & INSTALLATION



SOHC Engine

See Figures 1, 2, 3 and 4

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the timing chain front cover.
  4.  

During timing chain and sprocket removal, position the crankshaft 90 degrees past Top Dead Center (TDC), to make sure the pistons will not contact the valves upon assembly.

  1. Carefully rotate the crankshaft clockwise so the timing mark on the crankshaft sprocket and keyway align with the main bearing cap split line (90 degrees past TDC).
  2.  
  3. Remove bolts, then remove the timing guides and tensioner.
  4.  
  5. Remove the camshaft sprocket bolt, using a 7 / 8 in. (21mm) wrench to hold the camshaft. Then remove the timing chain and camshaft sprocket. Remove the crankshaft sprocket, if necessary.
  6.  

To install:
  1. Inspect the chain for wear and damage. Check the inside diameter of the chain, it should be no more than 16.77 in. (426mm). Inspect the chain guides for wear or cracks and the timing sprockets for teeth or key wear. Replace components as necessary.
  2.  
  3. Verify that the crankshaft is positioned 90 degrees clockwise past TDC from the keyway (keyway at 3 o'clock).
  4.  
  5. Bring the camshaft up to No. 1 TDC by loosely installing the sprocket and rotating the sprocket until the timing pin can be inserted. The camshaft contains wrench flats to assist in turning the shaft. The dowel pin should be at 12 o'clock when the camshaft is at TDC and a timing pin ( 3 / 16 in. drill bit) should then install at about the 8 o'clock position.
  6.  
  7. If removed, install the crankshaft sprocket, then rotate the crankshaft counterclockwise 90 degrees up to No. 1 TDC (keyway at 12 o'clock).
  8.  
  9. Position the chain under the crankshaft sprocket and over the camshaft sprocket. If necessary remove the camshaft sprocket, then slide the camshaft sprocket into position with the chain already engaged. The timing chain should be positioned so that one silver link plate aligns with the reference mark on the camshaft sprocket and the other aligns with the downward tooth (at the 6 o'clock position) on the crankshaft sprocket. The letters FRT on the camshaft sprocket must face forward, away from the cylinder head and excess chain slack should be located on the tensioner side of the block.
  10.  
  11. Temporarily install the timing pin to verify proper alignment of the camshaft and sprocket, then install and tighten the sprocket bolt to 75 ft. lbs. (102 Nm). Again, use a wrench on the camshaft flats to hold the shaft in position while tightening the bolt. Do not allow the camshaft retaining bolt to torque against the timing pin or cylinder head damage will result.
  12.  
  13. Install the chain guides with the words FRONT facing out. Install the fixed guide first and verify the chain is snug against the guide, then install the pivot guide. Tighten the bolts to 19 ft. lbs. (26 Nm) and verify that the pivot guide moves freely.
  14.  
  15. Retract the tensioner plunger and pin the ratchet lever using a 1 / 8 in. No. 31 drill bit inserted in the alignment hole at the bottom front of the component. Install the tensioner and tighten the bolts to 14 ft. lbs. (19 Nm), then remove the drill bit.
  16.  
  17. Make one final check to verify all components are properly timed, then remove all timing pins.
  18.  
  19. Install the timing chain front cover.
  20.  
  21. Connect the negative battery cable, start the engine and check for leaks.
  22.  



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Fig. Fig. 1: At 90 degrees past TDC, the crankshaft sprocket timing mark and keyway will align with the main bearing cap split line



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Fig. Fig. 2: Exploded view of the timing chain and sprocket assembly-SOHC engine



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Fig. Fig. 3: Insert the timing pin to ensure that the camshaft is at No. 1 TDC-SOHC engine



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Fig. Fig. 4: When the camshaft is at TDC, rotate the crankshaft counterclockwise 90 degrees to achieve TDC

DOHC Engine

See Figures 5 through 14

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the timing chain front cover.
  4.  

During timing chain and sprocket removal, position the crankshaft 90 degrees past Top Dead Center (TDC) to make sure the pistons will not contact the valves upon assembly.

  1. Carefully rotate the crankshaft clockwise so the timing mark on the crankshaft sprocket and keyway align with the main bearing cap split line.
  2.  
  3. Remove the bolts, then remove the timing guides and tensioner.
  4.  
  5. Remove the camshaft sprocket bolts, using a 7 / 8 in. (21mm) wrench to hold the camshaft. Then remove the timing chain and camshaft sprocket. Remove the crankshaft sprocket, if necessary.
  6.  

To install:
  1. Inspect the chain for wear and damage. Check the inside diameter of the chain, it should be no more than 23.15 in. (588mm). Inspect the chain guides for wear or cracks and the timing sprockets for teeth or key wear. Replace components as necessary.
  2.  
  3. Verify that the crankshaft is positioned 90 degrees clockwise past TDC. The crankshaft keyway should be at 3 o'clock aligned with the main bearing cap split line to prevent piston and valve damage.
  4.  
  5. Install the camshaft sprockets, retaining bolts and washers. Make sure the letters FRT on the sprockets face forward, away from the cylinder block. Use the wrench flats provided on the camshafts to hold the shaft and tighten the bolts to 75 ft. lbs. (102 Nm).
  6.  
  7. Bring the camshafts up to No. 1 TDC by rotating the camshafts and sprocket until the dowel pins are at 12 o'clock. Install a 1 / 6 in. drill bit into the hole in the sprocket about 9 o'clock.
  8.  
  9. If removed, install the crankshaft sprocket, then rotate the crankshaft counterclockwise 90 degree up to No. 1 TDC (keyway and sprocket timing mark at 12 o'clock, in alignment with the block timing mark).
  10.  
  11. Position the timing chain under the crankshaft sprocket and over the camshaft sprockets so 2 silver link plates align with the reference marks on the camshaft sprockets and another 2 plates align with the downward tooth (at 6 o'clock position) on the crankshaft sprocket. Excess chain slack should be located on the tensioner side of the cylinder block.
  12.  
  13. Verify that the crankshaft reference mark aligns with the cylinder block mark at 12 o'clock and that the timing pins are installed in the holes at about the 9 o'clock position. Remove the timing pins from the camshaft sprockets.
  14.  
  15. Install the timing chain fixed guide to the right of the block face toward the water pump. Tighten the bolts to 21 ft. lbs. (28 Nm) and verify the chain is snug against the guide.
  16.  
  17. Install the pivoting chain guide and check for clearance between the block and head. Tighten the bolt to 19 ft. lbs. (26 Nm) and verify the guide pivots freely.
  18.  
  19. Install the 2 forward camshaft bearing caps and the upper timing chain guide, then tighten the retaining bolts to 124 inch lbs. (14 Nm).
  20.  
  21. Retract the tensioner plunger and pin the ratchet lever using a 1 / 8 in. (3.18mm) No. 31 drill bit inserted in the alignment hole at the lower front of the component. Install the tensioner and tighten the bolts to 14 ft. lbs. (19 Nm), then remove the drill bit.
  22.  
  23. Make one final check to verify all components are properly timed, then remove all timing pins.
  24.  
  25. Install the timing chain front cover.
  26.  
  27. Connect the negative battery cable, start the engine and check for leaks.
  28.  



Click image to see an enlarged view

Fig. Fig. 5: Rotate the crankshaft clockwise until the timing mark on the crankshaft sprocket and keyway align with the main bearing cap split line



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Fig. Fig. 6: Loosen the timing chain tensioner mounting bolt ...



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Fig. Fig. 7: ... and remove the tensioner from the engine block



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Fig. Fig. 8: Retract the tensioner plunger and pin the ratchet lever with a 1/8 in. (3.18mm) drill bit inserted in the alignment hole



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Fig. Fig. 9: Remove the mounting fasteners from both timing guides ...



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Fig. Fig. 10: ... and remove the timing guides from the engine



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Fig. Fig. 11: Remove the camshaft sprocket bolts, using a 7/8 in. (21mm) wrench to hold the camshaft



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Fig. Fig. 12: Remove the timing chain and camshaft sprockets



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Fig. Fig. 13: Insert the timing pins to verify that the camshafts are at TDC



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Fig. Fig. 14: Make sure that the silver link plates and reference marks are all in alignment as shown

 
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