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Thread: Replacing Valve Springs and Valve Seals in a 2003 Z06

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  1. #1
    Join Date
    Feb 2012
    Posts
    25

    Default Replacing Valve Springs and Valve Seals in a 2003 Z06

    I plan to replace the valve springs and valve seals in my 2003 Z06. I will be using a Comp Cams 5642 valve spring compressor to compress the springs. I have read the service manual, read several write-ups by people who have performed this job, and watched several videos. I have not done this job myself. I have included my job plan and would appreciate the opinions of those who have performed this job. Thank you.

    1. Chock front tires.
    2. Blow dirt away from spark plugs and remove and number plugs.
    3. Remove coil packs and valve covers.
    4. Raise rear of car.
    5. With transmission in 6th gear rotate rear wheel assembly until both valves on cylinder #1 are closed. This is top dead center.
    6. Mark crankshaft pulley.
    7. Remove rocker arm bolts, rocker arms, and rocker arm pivot support and place in appropriate location in parts tray.
    8. Install Comp Cams 5462 valve spring compressor at cylinder #1, and compress valve springs.
    9. Remove valve stem keys and release valve spring tension. Place valve keys in appropriate location in parts tray.
    10. Remove valve spring caps and place in parts tray.
    11. Remove valve springs. Remove valve stem oil seals.
    12. Clean the valve stem seats.
    13. Lubricate valve guides and valve stem oil seals with clean engine oil.
    14. Install valve stem oil seals, using appropriate seal for intake and exhaust valves.
    15. Install new valve springs.
    16. Install valve spring caps.
    17. Use valve spring compressor to compress valve springs.
    18. Use assembly grease to hold keys in place and make sure that keys seat properly in the groove of the valve stem.
    19. Carefully release the valve springs.
    20. Gently tap the end of the valve stems to seat the keys.
    21. Rotate rear tire assembly so that crankshaft pulley is rotated 90 degrees.
    22. Repeat above procedure on cylinder #8.
    23. The engine firing order is 1,8,7,2,6,5,4,3. Continue with this procedure until all valve springs and seals have been completed.
    24. With cylinder #1 at TDC tighten the following rocker arm bolts:
    Tighten the exhaust valve rocker arm bolts 1,2,7, and 8 to 22 lb-ft.
    Tighten the intake valve rocker arm bolts 1,3,4,and 5 to 22 lb-ft.
    25. Rotate the crankshaft 360 degrees. Tighten the following rocker arm bolts:
    Tighten the exhaust valve rocker arm bolts 3,4,5, and 6 to 22 lb-ft.
    Tighten the intake valve rocker arm bolts 2,6,7, and 8 to 22 lb-ft.
    26. Install the rocker arm covers and tighten bolts to 106 lb-in.
    27. Install the coil pack bracket. Apply threadlock to the bracket studs and tighten to 106 lb-in.
    28. Install spark plugs with one drop of synthetic oil on threads and tighten to 11 lb-ft.
    29. Install spark plug wires.

  2. #2
    Join Date
    Dec 2011
    Location
    Washington State
    Posts
    534

    Default

    Maybe I missed it, but I didn't see where compressed air goes into the cylinder to hold the valves up when you remove the keeper. Also make darn sure that each cylinder is on the compression stroke.
    20+ years ASE and Honda Master Tech

    1998 black 6 spd convertible

  3. #3
    Join Date
    Feb 2012
    Posts
    25

    Default

    Thank you very much for your reply.
    On the ls6 I have read that it is not possible for the valve to drop into the cylinder when the piston is at top dead center. That is why I plan to initially rotate the crankshaft with the valve train intact as I can verify that the valves in cylinder #1 are fully closed. By marking the crankshaft pulley, knowing the firing order, and that the engine fires every 90 degrees I can get TDC on all cylinders. I do plan to use compressed air but I don't want to rely too heavily on air pressure. I like the TDC physical barrier.
    Many internet articles recommend inserting a piece of rope or a dowel through the spark plug hole to prevent the valves from dropping instead of using compressed air. As you are a master mechanic with a lot of experience I would appreciate your opinion on those methods. Thank you.

  4. #4
    Join Date
    Dec 2011
    Location
    Washington State
    Posts
    534

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    If you have the piston at TDC on the compression stroke with no air pressure the valve can still drop down until it contacts the piston, which means that it will not fully drop into the cylinder since the piston is up, but it will make it almost impossible to reinstall the keepers. I would only do this job with compressed air and verify that every cylinder is on the compression stroke.
    20+ years ASE and Honda Master Tech

    1998 black 6 spd convertible

  5. #5
    Join Date
    Jul 2016
    Posts
    9

    Default

    Quote Originally Posted by LLC5 View Post
    If you have the piston at TDC on the compression stroke with no air pressure the valve can still drop down until it contacts the piston, which means that it will not fully drop into the cylinder since the piston is up, but it will make it almost impossible to reinstall the keepers. I would only do this job with compressed air and verify that every cylinder is on the compression stroke.
    When the rockers are removed there is no need to know which stroke you are on!
    The air hold adapter is like $10 and any compressor will work, just buy/rent/borrow one
    AND take your time you don't want a keeper popping out on the road

    Sent from my SM-T530NU using Tapatalk

  6. #6
    Join Date
    Feb 2012
    Posts
    25

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    Thank you very much for your advice, which I will follow when I do the job.

  7. #7
    Join Date
    May 2013
    Posts
    20

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    I've heard of the C5 Z06's "weaker" valve spring issue... what model years supposedly have them?

    I have a 2001 Z06 with 79,000 miles, and I am wondering if I should/need to replace mine as well, at least for peace of mind...?
    Thanks!

  8. #8
    Join Date
    Feb 2012
    Posts
    25

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    It took a while to get to it but I completed this project. The Comp Cams 5462 valve spring compressor made compressing the valve springs really easy. I used a Snap-on 24 mm deep offset wrench to rotate the crankshaft and that worked really well. I also replaced the spark plugs and wires and the engine runs much smoother now.

  9. #9
    Join Date
    Jul 2008
    Location
    Ontario, Calif.
    Posts
    2,978

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    2015 Stingray Z51 w/ Magnetic Ride Control & 8-speed Automatic


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