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  1. #1

    Default Knocking sound when starting...loudest when engine is cold

    2001 k1500 5.3 with 104,000 miles. Started several months ago when engine was started but would get quiet after 10 or 20 seconds. Now it knocks longer and louder but does eventually get quiet. Sounds louder than a lifter. I'm wondering if a piston. I bought the truck about 4 or 5 years when it had 56 thousand on it. Truck looked new when I bought it and did not notice and problems with engine. Since then it has gotten fresh oil every 3000-4000 thousand. Most of my miles are highway. And from the look of the truck I'd guess most of the previous owners mileage where highway.

    I'm bummed!!

  2. #2
    Jr. Mechanic ibmoses's Avatar
    Join Date
    Mar 2008
    "Sweet Home Alabama"


    What oil are you using?

    Sounds like piston slap.

    "Race Car Spelled Backwards is Racecar"

    03 Silverado 2WD extended cab 5.3 with towing package white/silver

  3. #3

    dwill3015's Avatar
    Join Date
    Jan 2007
    Yacolt, Washington
    Blog Entries


    Welcome to the site! Check out THIS SITE for more info on piston slap.
    Washington State
    2006 Silverado 2500HD LT3 4X4 CC SB Duramax LBZ
    Tuff Country 6" lift, 35" Toyo M/T's on 20" Ultra Peacemaker wheels, Quadzilla Stealth2 programmer, Diamond Eye 5" cat-back exhaust, factory Special order color Yellow.

  4. #4


    this is commen in colder weather on silverado's i never seen these blow up what gm was doing was removing all the spark plugs and putting in top engine cleaner [nasty stuff ] leave in over night,crank it over with no plugs reinstall takes some time to get started because it washes the cylinders down,it will smoke like crazy and then change oil to mobil 1 they clame that it carbon build up hope this helps

  5. #5


    I have used pennzoil or castrol.

    I'll contact the local gm dealer and tell them I think I have excessive piston slap and see if they come up with the carbon buildup remover solution.

  6. #6


    My 2000 Silverado has the knocking sound when I first start it up in the morning. It has a 108k on it and the knock doesn't last too long. I was told that the early 5.3's were build very loose on the clearances. After reading the site that Darcy posted above it must be true.
    2000 Chevy Silverado LS Ext. Cab 5.3 2wd.
    -ChromeIntakes CAI
    -Single Inlet/Duel Outlet Flowmaster 2.25" Pass. Side Exit
    -20% Tint on Front Doors
    1997 Suzuki TL1000S
    2002 Kawasaki ZX9R F1
    1997 Honda CBR600F3
    1982 Yamaha XJ650RJ SECA

    Plumbers and Pipefitters Kansas L.U. 441
    5th. Yr. Apprentice

  7. #7


    Try some seafoam. Stuff works great for cleaning out carbon build up.

  8. #8


    Classic case of the Infamous Chevy Piston Slap. Plaguing Chevrolet owners across the nation.
    Current Daily Driver:
    2003 Chevrolet Silverado 1500 - 4WD - 4.8L V8 - True Dual Exhaust Setup, Cat Delete, Cherry Bomb Glass Packs

  9. #9
    Master Mechanic
    Join Date
    Oct 2008
    Brandon, FLA
    Blog Entries


    Darcy, where do you come up with these sites, man your amazing with some of these......It even has been back in the late '70's, but just not as noticable.....


  10. #10
    Master Mechanic Dr_Zero's Avatar
    Join Date
    Mar 2006
    Sunny Florida


    Quote Originally Posted by jlsparky7 View Post
    Try some seafoam. Stuff works great for cleaning out carbon build up.
    Would definitely try Seafoaming the intake it might take a couple of runs but it really does help. I put in the intake and the tank but dont like the idea of the oil.

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