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Chevy Silverado/GMC Sierra's w 8100/Allison



  • mgdvhmanmgdvhman Posts: 4,162
    man o man batman sure is hurting inside with his toy.........

    - Tim
  • nomoregmnomoregm Posts: 158
    OK, someone please correct me if I'm wrong.

    Piston Slap knock: Louder when engine/weather is cold and during lower RPMs. Then in some cases goes away. Non-detonation issue.

    Carbon Knock: Louder when engine/weather is hot and during higher RPMs. Will not go away. Detonation issue. Higher-octane/slower burning fuel should solve.

    Why then, Does GM refer to carbon build-up as a cold-start knocking issue in this TSB:

    Just seems to be contradictive.

    GM, I agree. In todays engines, with the taper of the piston tops and shorter skirts, some normal slapping will occur up to 1-2 or even 3 minutes in extreme cold weather. But those aluminum pistons should expand quickly and quiet down. (my 5.7 goes on for 15-25 minutes--most people agree that's not normal but GM says, "yes").

    If the pistons don't seat quickly, excessive blow-by will cause higher than normal air-pressure in the oil pan causing oil to be blown up into the valve cover and down from the top where it is burned in the combustion chamber. Higher oil "usage" from higher reving, higher compression engines might be normal, but oil "burning" from blow-by is not.


  • kg11kg11 Posts: 530
    Would you please quit agreeing with GM.1-2 or even 3 minutes of knocking IS NOT NORMAL.Yours on the other hand is seriously effed-up.15-25 minutes?And they won't fix it?I think sonjab was right about putting a brick on the gas pedal.

  • bamatundrabamatundra Posts: 1,583
    While I appreciate your brand loyalty, why should nomore have to accept a knocking engine? I know that you accept that knocking is "normal", but why should nomore have to accept your erroneous perception?

    GM needs to address this problem. The sooner - the better for their long term viability as a car(or truck) manufacturer.
  • kg11kg11 Posts: 530
    Why do you need to post here while crying to your mama about off topic posts in the Tundra topic.

    I know you're not stupid enough to think I said any of what you're "quoting" so just what is your purpose here?
    You KNOW I'm closer to a Toyota brand loyalist than GM,but unlike you I'm not going to tell people your Tundra is actually a truck.Tundra is the only toyota I don't care for. I consider it to be Toyota's second failure in the full sized market.I also think they'll get it right on the third attempt.
  • sonjaabsonjaab Posts: 1,057
    Have your friendly GM dealer do a oil
    change. Drive home. Drain oil. Start
    motor..Let it idle....When it seizes.
    Refill with oil...Call dealer !!!
    You are under warranty right ?
    I feel your pain I had 2 troublesome
    toyotas, 1 pos vette, 1 pos T/A..
    Dealers were NO help either.....
    Had to bite the bullet on all of them !
    But my last 4 GM trucks were great and
    I snowplowed and worked em, to death !
    Good luck......Geo
  • nomoregmnomoregm Posts: 158
    Can't do such a thing--too honest. Will not lower myself to GM's standards. Nothing against you, ol' man. I appreciate the advice. Besides, they can tell these days by taking the engine apart and the black-box computer on the cars. That stuff worked good in the 50's.

    KG11, I think you're right. I just wish mine would go away in 2 minutes--it doesn't. Kind of a drag, my friend. I hear what you're saying. When it comes to slingin' the BS, GM is King.

    Bama/KG, you know I really wish you guys could click (notice I didn't say, knock)--go out for a beer or something--doobie perhaps--little air-guitar. Life's too GD short. Love ya bro's.
  • woolybackwoolyback Posts: 45
    Hi, I have the shortbed GMC 2001 Sierra w,8100/Allison. I am thinking about replacing the 26 gal. fuel tank with a 45 gal. tank that mounts on the chassis that Transfer Flow makes. Has anyone gone this route yet with their shortbed and if so how easy or hard was the transition.
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