Nissan 240SX/Altima 1993-1998 Repair Guide

Timing Chain and Sprockets

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REMOVAL & INSTALLATION



See Figures 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 and 15



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Fig. Fig. 1: Use a small prybar to gently loosen the upper timing cover and remove it from the engine



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Fig. Fig. 2: The upper timing cover uses various length bolts for attachment. To avoid damage to the cylinder head, always replace bolts in their proper positions



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Fig. Fig. 3: When the engine is at TDC of the compression stroke on the No. 1 cylinder, the timing marks should align as shown



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Fig. Fig. 4: When removing the camshaft sprocket bolt, use a wrench to prevent the camshafts from moving



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Fig. Fig. 5: The upper timing chain uses both a top guard ...



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Fig. Fig. 6: ... and side guards to prevent the chain from contacting the covers as the chain slackens



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Fig. Fig. 7: Separate timing chain tensioners are used for each chain. This is the tensioner for the top chain



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Fig. Fig. 8: The camshaft sprocket bolt threads directly into the camshaft. Take care not to crossthread the bolt during installation



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Fig. Fig. 9: Prior to removing the upper timing chain, be sure the alignment links (arrow), which have a dab of paint on them, are aligned with the punch marks on the camshaft sprockets



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Fig. Fig. 10: The idler sprocket is attached to the cylinder head with a single bolt. Take care not to crossthread the bolt and damage the aluminum cylinder head



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Fig. Fig. 11: The stoppers on the camshaft sprocket cover and front cover prevent the timing chain from disengaging its sprockets



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Fig. Fig. 12: Lower timing chain tensioner and timing chain guide positioning



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Fig. Fig. 13: Position the lower timing chain so that its mating marks align with those on the crankshaft and idler sprockets



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Fig. Fig. 14: Ensure mating mark alignment of the upper timing chain and idler sprocket



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Fig. Fig. 15: Also be sure that the upper timing chain and camshaft sprocket mating marks align

Altima

See Figures 16, 17, 18 and 19



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Fig. Fig. 16: When removing the engine mount, raise the engine slightly using a floor jack beneath the oil pan. Protect the oil pan with a piece of wood



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Fig. Fig. 17: It is necessary to remove the passenger's side engine mount to remove the cam sprocket cover



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Fig. Fig. 18: Once the passenger's side engine mount is removed, access to the upper timing cover is much easier



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Fig. Fig. 19: Remove the bracket to access this hidden bolt (arrow) that retains the upper timing cover

  1. Disconnect the negative battery cable.
  2.  
  3. Drain and recycle the engine coolant.
  4.  
  5. Drain and recycle the engine oil.
  6.  
  7. Remove the engine undercover.
  8.  
  9. Label and disconnect all appropriate vacuum hoses, fuel lines, wires and electrical harnesses.
  10.  
  11. Remove the alternator and bracket, upper radiator hose, air duct, and front exhaust tube.
  12.  
  13. Remove the intake manifold collector supports, intake manifold collector, and exhaust manifold.
  14.  
  15. Set the No. 1 piston at TDC on its compression stroke.
  16.  
  17. Remove the distributor.
  18.  
  19. Position a floor jack with a block of wood beneath the aluminum oil pan and remove the passenger's side engine mount.
  20.  
  21. Remove the cylinder head cover. Remove the cylinder head cover bolts in the proper sequence.
  22.  
  23. Remove the camshaft sprockets.
  24.  

The stoppers on the camshaft covers prevent the upper timing chain from disengaging the idler sprocket.

  1. Remove the cam bearing caps in the proper sequence and remove the camshafts. The camshaft brackets must be loosened in reverse order of the tightening sequence to prevent damage to the camshaft.
  2.  

These parts must be reassembled in their original positions.

  1. Loosen the cylinder head bolts in the reverse order of installation.
  2.  

A warped or cracked cylinder head could result from loosening in an incorrect order. The cylinder head bolts should be loosened in two or three steps.

  1. Remove the cam sprocket cover.
  2.  
  3. Remove the upper chain tensioner and upper chain guides.
  4.  
  5. Remove the upper timing chain.
  6.  
  7. Remove the idler sprocket bolt.
  8.  

The stoppers on the front cover prevent the lower timing chain from disengaging the crankshaft sprocket.

  1. Remove the cylinder head and gasket.
  2.  
  3. Remove the oil pan.
  4.  
  5. Remove the crankshaft damper.
  6.  
  7. Remove the front cover.
  8.  
  9. Remove the oil pump drive spacer.
  10.  
  11. Remove the lower timing chain tensioner, tension arm, and lower timing chain guide.
  12.  
  13. Remove the lower timing chain and idler sprocket.
  14.  

To install:
  1. Install the crankshaft sprocket and oil pump drive spacer.
  2.  

Ensure that the mating marks on the crankshaft sprocket face the front of the engine.

  1. Set the No. 1 piston at TDC on its compression stroke.
  2.  
  3. Install the idler sprocket and lower timing chain.
  4.  
  5. Set the lower timing chain on the sprockets, aligning the mating marks.
  6.  

The mating marks on the timing chain assembly will be silver.

  1. Install the chain tension arm and chain guide.
  2.  
  3. Install the lower timing chain tensioner.
  4.  
  5. Install a new front cover oil seal.
  6.  
  7. Apply a continuous bead of liquid gasket, as illustrated, to the front cover.
  8.  
  9. Install the front cover. Tighten the M6 attaching bolts to 56-66 inch lbs. (6.4-7.5 Nm). Tighten the M8 attaching bolts to 12-14 ft. lbs. (16-19 Nm).
  10.  
  11. Install the crankshaft damper.
  12.  
  13. Install the oil strainer and oil pan.
  14.  
  15. When installing the front cover, install the cylinder head. Insert, but do not tighten the cylinder head bolts.
  16.  

Apply engine oil to the bolt threads and seat surfaces. Ensure that the washers between the bolts and cylinder head are properly positioned.

  1. Temporarily tighten the cylinder head bolts.
  2.  

This is necessary to avoid damaging the cylinder head gasket.

  1. Install the upper timing chain, chain tensioner and chain guide.
  2.  
  3. Set the upper timing chain on the idler sprocket, aligning the mating marks.
  4.  
  5. Apply a continuous bead of liquid gasket, as illustrated, to the cam sprocket cover.
  6.  
  7. Install the cam sprocket cover.
  8.  

Be careful not to damage the cylinder head gasket. Be careful that the upper timing chain does not slip or jump when installing the cam sprocket cover.

  1. Tighten the cylinder head bolts in the indicated sequence to the proper specification.
  2.  
  3. Install the camshafts and camshaft bearing caps.
  4.  
  5. Install the camshaft sprockets (with the chain attached).
  6.  
  7. Install the chain guide between both camshaft sprockets.
  8.  

The alignment marks on the upper portion of the timing chain should now be aligned.

  1. Install the distributor. Ensure that the No. 1 piston is set at TDC and the distributor rotor is set at No. 1 cylinder spark position.
  2.  
  3. Install the cylinder head cover and tighten the attaching bolts in the indicated sequence to the proper specification.
  4.  
  5. Install the intake manifold collector, intake manifold collector supports, and exhaust manifold.
  6.  
  7. Install the alternator and bracket, upper radiator hose, air duct, and front exhaust tube.
  8.  
  9. Connect all appropriate vacuum hoses, fuel lines, wires and electrical harnesses.
  10.  
  11. Install the engine undercover.
  12.  
  13. Refill the engine with the correct grade and viscosity of engine oil.
  14.  
  15. Refill and bleed the cooling system.
  16.  
  17. Connect the negative battery cable.
  18.  
  19. Start the engine and make the necessary adjustments.
  20.  
  21. Check for proper operation and leaks.
  22.  

240SX
  1. Disconnect the negative battery cable.
  2.  
  3. Drain and recycle the engine coolant.
  4.  
  5. Drain and recycle the engine oil.
  6.  
  7. Remove the engine undercover, as required.
  8.  
  9. Label and disconnect all appropriate vacuum hoses, fuel lines, wires and electrical harnesses.
  10.  
  11. Remove the intake and exhaust manifolds.
  12.  
  13. Remove the air duct, cooling fan and radiator shroud.
  14.  
  15. Remove the spark plugs and ignition wires.
  16.  
  17. Set the No. 1 piston at TDC on its compression stroke.
  18.  
  19. Remove the distributor.
  20.  
  21. Unfasten the cylinder head cover bolts in the proper sequence, then remove the cylinder head cover.
  22.  
  23. Remove the camshaft sprockets.
  24.  

The stoppers on the camshaft covers prevent the upper timing chain from disengaging the idler sprocket.

  1. Remove the camshaft bearing caps in proper sequence and remove the camshafts. The camshaft brackets must be loosened in reverse order of tightening to prevent damage to the camshaft.
  2.  

These parts must be reassembled in their original positions.

  1. Loosen the cylinder head bolts in the reverse order of installation.
  2.  

A warped or cracked cylinder head could result from loosening in incorrect order. The cylinder head bolts should be loosened in two or three steps.

  1. Remove the cam sprocket cover.
  2.  
  3. Remove the upper chain tensioner and upper chain guides.
  4.  
  5. Remove the upper timing chain.
  6.  
  7. Remove the idler sprocket bolt.
  8.  

The stoppers on the front cover prevent the lower timing chain from disengaging the crankshaft sprocket.

  1. Remove the cylinder head and gasket.
  2.  
  3. Remove the upper timing chain.
  4.  
  5. Remove the oil pan.
  6.  
  7. Remove the crankshaft damper.
  8.  
  9. Remove the front cover.
  10.  
  11. Remove the oil pump drive spacer.
  12.  
  13. Remove the lower timing chain tensioner, tension arm, and lower timing chain guide.
  14.  
  15. Remove the lower timing chain and idler sprocket.
  16.  

To install:
  1. Install the crankshaft sprocket and oil pump drive spacer.
  2.  

Ensure that the mating marks on the crankshaft sprocket face the front of the engine.

  1. Set the No. 1 piston at TDC on its compression stroke.
  2.  
  3. Install the idler sprocket and lower timing chain.
  4.  
  5. Set the lower timing chain on the sprockets, aligning the mating marks.
  6.  

The mating marks on the timing chain assembly will be silver.

  1. Install the chain tensioner arm and chain guide.
  2.  
  3. Install the lower timing chain tensioner.
  4.  
  5. Install a new front cover oil seal.
  6.  
  7. Apply a continuous bead of liquid gasket, as illustrated, to the front cover.
  8.  
  9. Install the front cover. Tighten the M6 attaching bolts to 56-66 inch lbs. (6.4-7.5 Nm). Tighten the M8 attaching bolts to 12-14 ft. lbs. (16-19 Nm).
  10.  
  11. Install the crankshaft damper.
  12.  
  13. Install the oil strainer and oil pan.
  14.  
  15. When installing the front cover, install the cylinder head. Insert, but do not tighten the cylinder head bolts.
  16.  

Apply engine oil to the bolt threads and seat surfaces. Ensure the washers between the bolts and cylinder heads are properly positioned.

  1. Temporarily tighten the cylinder head bolts.
  2.  

This is necessary to avoid damaging the cylinder head gasket.

  1. Install the upper timing chain, chain tensioner and chain guide.
  2.  
  3. Set the upper timing chain on the idler sprocket, aligning the mating marks.
  4.  
  5. Apply a continuous bead of liquid gasket, as illustrated, to the cam sprocket cover.
  6.  
  7. Install the cam sprocket cover.
  8.  

Be careful not to damage the cylinder head gasket. Be careful that the upper timing chain does not slip or jump when installing the cam sprocket cover.

  1. Tighten the cylinder head bolts in the indicated sequence to the proper specification.
  2.  
  3. Install the camshafts and camshaft bearing caps.
  4.  
  5. Install the camshaft sprockets (with the chain attached).
  6.  
  7. Install the chain guide between both camshaft sprockets.
  8.  

The alignment marks on the upper portion of the timing chain should now be aligned.

  1. Install the distributor. Ensure the No. 1 piston is set at TDC and the distributor rotor is set at No. 1 cylinder spark position.
  2.  
  3. Install the cylinder head cover and tighten the attaching bolts in the indicated sequence to the proper specification.
  4.  
  5. Install the spark plugs and ignition wires.
  6.  
  7. Install the air duct, cooling fan and radiator shroud.
  8.  
  9. Install the intake and exhaust manifolds.
  10.  
  11. Connect all appropriate vacuum hoses, fuel lines, wires and electrical harnesses.
  12.  
  13. Install the engine undercover, as required.
  14.  
  15. Refill the engine with the correct grade and viscosity of engine oil.
  16.  
  17. Refill and bleed the cooling system.
  18.  
  19. Connect the negative battery cable.
  20.  
  21. Start the engine and make the necessary adjustments.
  22.  
  23. Check for proper operation and leaks.
  24.  

 
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