Timing Chain: Service and Repair
REMOVAL1. Remove timing cover.
2. Rotate crankshaft keyway to 11 o'clock location to position crankshaft at Top Dead Center (TDC) No. 1 cylinder.
3. Verify alignment arrows on camshafts are aligned. If arrows are not aligned, rotate crankshaft one complete revolution.
4. Rotate crankshaft to position crankshaft keyway to three o'clock position. This will position righthand cylinder head camshafts to neutral position (base circle).
5. Remove righthand timing chain tensioner bolts, then tensioner.
6. Remove cylinder head camshaft journal thrust cap bolts and thrust caps from righthand cylinder head, noting following:
a. Remove cylinder head camshaft journal thrust caps first to ensure damage to the thrust caps does not occur.
b. Cylinder head camshaft journal caps and cylinder heads are numbered to ensure they are assembled in original positions. If removed, keep camshaft journal caps from each cylinder head together. Do not mix with caps from another cylinder head.
Camshaft journal cap bolt removal sequence:
7. Loosen remaining righthand cylinder head camshaft journal cap bolts in sequence, seven to eight revolutions, in several passes, to allow camshafts to be raised from righthand cylinder head. Do not completely remove bolts.
8. With crankshaft keyway at three o'clock location and righthand cylinder head camshaft journal caps and camshafts loose on righthand cylinder head, remove rocker arms.
NOTE: If valve tappets and roller rocker arms are to be reused, mark position of rocker arms and valve tappets to ensure they are assembled in original positions.
9. Remove righthand timing chain tensioner arm and righthand timing chain. If righthand tensioner arm and chain guide are to be reused, mark position of tensioner arm and chain guide to ensure they are assembled in original positions.
Exploded View (Righthand shown, lefthand similar):
10. Remove righthand timing chain guide bolts, then guide.
11. Remove righthand timing chain crankshaft sprocket, then rotate crankshaft two revolutions and position crankshaft keyway to 11 o'clock location. This will position lefthand cylinder head camshafts to neutral position (base circle).
12. Verify alignment arrows on camshaft are aligned, then remove lefthand timing chain tensioner bolts and tensioner.
13. Remove cylinder head camshaft journal thrust cap bolts and caps from lefthand cylinder head, noting following:
a. Remove cylinder head camshaft journal thrust caps first to ensure damage to the thrust caps does not occur.
b. Cylinder head camshaft journal caps and cylinder heads are numbered to ensure they are assembled in original positions. If removed, keep camshaft journal caps from each cylinder head together. Do not mix with camshaft journal caps from another cylinder head.
Camshaft journal cap bolt removal sequence:
14. Loosen remaining lefthand cylinder head camshaft journal cap bolts in sequence, in seven to eight revolutions, to allow camshafts to be raised from cylinder heads. Do not completely remove bolts.
15. With crankshaft keyway at 11 o'clock location and lefthand cylinder head camshaft journal caps and camshafts loose on lefthand cylinder head, remove rocker arms.
NOTE: If valve tappets and roller rocker arms are to be reused, mark position of rocker arms and valve tappets to ensure they are assembled in original positions.
16. Remove lefthand timing chain tensioner arm and lefthand timing chain.
NOTE: If lefthand tensioner arm and chain guide are to be reused, mark position of tensioner arm and chain guide to ensure they are assembled in original positions.
17. Remove lefthand timing chain guide bolts, then guide.
18. Remove lefthand timing chain crankshaft sprocket, then inspect timing chain tensioners, tensioner arms, guides, crankshaft sprockets and timing chains for wear or damage. Replace components as necessary.
19. Using small screwdriver, release timing chain tensioner ratchet/pawl mechanism through access hole in tensioner.
20. Compress tensioner rack and piston into tensioner housing by inserting small wire into top of piston and gently unseat oil check ball, then compress tensioners by hand.
Fig. 24 Timing chain tensioner compression:
21. With tensioner rack and piston compressed, install 0.06 inch drill bit or wire into small hole above ratchet, engaging lock groove in rack of timing chain tensioners.
CAUTION: Timing tensioners must be installed onto engine while compressed and locked. Failure to compress timing chain before installing may cause damage to engine.
22. If timing chain guides, tensioner arms or chains show premature wear or damage, also replace camshaft damper.
INSTALLATION
1. Ensure crankshaft keyway is at 11 o'clock location, then install lefthand timing chain crankshaft sprocket onto crankshaft, aligning key with keyway on sprocket. Crankshaft keyway must be at 11 o'clock location before assembly. If not in this location, engine damage may result.
2. Install lefthand timing chain guide to engine.
3. Verify alignment arrows on camshafts are aligned with each other, then install lefthand timing chain over lefthand crankshaft sprocket and lefthand camshaft sprockets.
4. Align timing index marks on lefthand timing chain with timing index marks on lefthand crankshaft sprocket and camshaft sprockets.
5. Install lefthand timing chain tensioner arm over alignment dowel on lefthand cylinder head, then install compressed lefthand timing chain tensioner and bolts onto cylinder block.
CAUTION: Timing chain tensioners must be installed onto engine while compressed and locked. Failure to compress tensioners before installation may cause damage to engine.
Fig. 25 Lefthand timing chain index mark alignment:
6. Verify timing index marks on lefthand timing chain are in alignment with timing index marks on lefthand crankshaft sprocket and camshaft sprockets.
7. Install righthand timing chain crankshaft sprocket onto crankshaft, then align crankshaft key with keyway on crankshaft sprocket.
8. Install righthand timing chain guide and bolts to engine.
9. Verify alignment arrows on camshafts are aligned with each other, then install righthand timing chain over righthand crankshaft sprocket and righthand camshaft sprockets. Align timing index marks on righthand timing chain with timing index marks on righthand crankshaft sprocket and camshaft sprockets.
10. Install righthand timing chain tensioner arm over alignment dowel on righthand cylinder head.
11. Install compressed righthand timing chain tensioner and bolts onto cylinder block.
CAUTION: Timing chain tensioners must be installed onto engine while compressed and locked. Failure to compress tensioners before installation may cause damage to engine.
Fig. 26 Righthand timing chain index mark alignment:
12. Verify timing index marks on righthand timing chain are in alignment with timing index marks on righthand crankshaft sprocket and camshaft sprockets.
13. Lubricate rocker arms with suitable engine assembly lubricant, then install rocker arms onto lefthand cylinder head under camshafts. Ensure rocker arms are installed in original locations.
CAUTION: Crankshaft keyway must be at 11 o'clock location before installing lefthand cylinder head rocker arms. Failure to do so may lead to engine damage.
camshaft journal cap bolt tightening sequence.:
14. With lefthand cylinder head rocker arms installed, tighten lefthand cylinder head camshaft journal cap bolts in sequence, in several passes, to 5.9-8.8 ft lb. Do not install cylinder head camshaft journal thrust caps until camshaft journal caps are installed or damage to thrust caps may occur.
15. With lefthand cylinder camshaft journal caps installed and camshafts aligned with thrust caps, install thrust caps and tighten bolts to 5.9-8.8 ft lb.
16. Rotate crankshaft two revolutions and position crankshaft keyway to three o'clock location. This will position righthand cylinder head camshafts to neutral position (base circle).
17. Lubricate rocker arms with suitable engine assembly lubricant, then install rocker arms onto righthand cylinder head under camshafts.
CAUTION: Ensure rocker arms are installed in original locations. Crankshaft keyway must be at three o'clock location before installing righthand cylinder head rocker arms. Failure to do so may lead to engine damage.
camshaft journal cap bolt tightening sequence.:
18. With righthand cylinder head rocker arms installed, tighten righthand cylinder head camshaft journal cap bolts in sequence, in several passes, to 5.9-8.8 ft lb. Do not install cylinder head camshaft journal thrust caps until camshaft journal caps are installed or damage to thrust caps may occur.
19. With righthand cylinder camshaft journal caps installed and camshafts aligned with thrust caps, install thrust caps.
Fig. 25 Lefthand timing chain index mark alignment:
20. Remove lock pins from timing chain tensioners, then verify index timing marks on timing chains are in alignment with timing index marks on crankshaft and camshaft sprockets.
21. Install timing cover.