Advice? Knocking

Discussion in 'GM Powertrain' started by Silverado1500, Dec 25, 2009.

  1. Silverado1500

    Silverado1500 Rockstar 100 Posts

    i have a 2000 silverado that i bought about a month now with 102k. i had just changed the oil about a week ago. then about 3 days after that it started knocking, but it started to get cold too, with 10+ inches of snow.
    is this piston slap? if so what can i do to fix it?

    how many of you guys recommend seafoam? is it really safe?
  2. jt_5.7

    jt_5.7 Rockstar

    no my friend put that in his skylark and it blew up a week later
  3. vncj96

    vncj96 Epic Member 5+ Years 1000 Posts

    never had a problem with seafoam, nor have i ever heard of anyone on this sight having a problem with it, just search seafoam, there have been TONS of posts about it
  4. Silverado1500

    Silverado1500 Rockstar 100 Posts

    used it on my truck. works great!
  5. Logictox

    Logictox New Member

    Is this a knock or a rattle when cold? These engines have zero piston skirts and from the first year they came out at 20k plus miles there was a large number of cold engine piston rattles. The condition doesn't seem to effect longevity but it does sound terrible for the first several minutes of operation. It was discovered that removing carbon from the piston did reduce the noise for a short period of time. If you have a knock that is a different issue, a knock will usually get worse as the engine gets warmer while the rattle I refer to will go away as the engine warms up.
  6. BillNH

    BillNH New Member

    If it only happens when the eng is cold it is common and doesn't effect the eng. Like the previous post it is a carbon build up issue.
  7. kc2qhe

    kc2qhe New Member

    also common in the newer gen engines is oil pump drive noise, by your desciption, i would guess put 10w30 in motor instead of 5w30. try to stick to the 5w, as this will help quiet the noise quicker. many of these trucks around here have the common noise, mine included, since 30k. running strong at 165k synthetic always since 30k quieted it down. good luck.
  8. Silverado1500

    Silverado1500 Rockstar 100 Posts

    thanks alot guys, much appreciated

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