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bad engine knock! PLEASE HELP!!!

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by yeevveey211, Mar 16, 2013.

  1. yeevveey211

    yeevveey211 New Member

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    what's up guys I own a 2005 chevy 2500 reg cab 6.0l with a 7"BDS ntbd. need some help here I've been looking on other forums trying to figure out what my loud obnoxious engine knocking is .
    so I get home on Sunday from work go to bed. wake up Monday morning start my truck up and sounds like a freaking hammer hitting . my oil is good no metal in it. the lubricity is good I don't even know if that's a word but yeah. also I was reading about flex plates bending . I'm pretty sure it's not that. sound like passenger side lower area. checked for broken exhaust studs none are missing ., I'm at a stand still . just weird how this happened over night. . I don't know if it's a bad intake manifold gasket . but yet again I am not loosing coolant. also I was wondering if it could be a injector ?? making piston slap. or bad knock sensor. have the timing off . it's bad enough that it vibrates my whole truck.


    please help I would really appreciate it
    #1
  2. j cat

    j cat Active Member

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    it would be rare to have the engine fail on start up . you do anything to stress out this engine lately ?

    possible coolant leaked into a cylinder and on starting it broke the piston.
    #2
  3. yeevveey211

    yeevveey211 New Member

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    haven't done anything to stress the motor out. she's my only ride and go about a mile and back ever day for work . try not to be too lead footed . gas is $$.
    i checked coolant level and it was perfect and and normal height
    #3
  4. j cat

    j cat Active Member

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    pull the plugs see what they look like. could also be injector leaking into a cylinder doing the same thing.
    #4
  5. yeevveey211

    yeevveey211 New Member

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    ok I will pull injector . how would I know if injector is not working properly? hold a peice of white paper under it ?

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    i have also read about the starter not fully engaging back complelty . to make a nasty noise of which I am hearing . I guess the bendix starters start to take a crap over a 100k which seems about right to what I hear .
    #5
  6. geo1

    geo1 New Member

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    if you have a fuel pressure gauge,that will determine leaking injector,i.e.quick drop in pressure,i agree with posts above,also while each spark plug is out,start it,this way also you can isolate to a specific cylinder,be quick about it so you dont harm cat.with unburned fuel
    #6
  7. j cat

    j cat Active Member

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    starter noise don't sound like pistons . these engines start very fast and I have yet to see starter failures of the drive/gears etc. usually the solenoids fail [no crank]
    #7
  8. yeevveey211

    yeevveey211 New Member

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    i have ran a code and it runs a p0300 misfire on multiple cylinders . I had got a full tank of gas during the same week she took a crap. could possible be contaminated fuel ? water in fuel?
    #8
  9. geo1

    geo1 New Member

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    po300 is a pita.go to dealership and have a crankshaft relearn procedure done,only way i know of to get rid of that one,might not be out of the woods yet,so might have to wait on next code to appear,i.e. a hard code
    #9
  10. j cat

    j cat Active Member

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    p0300 being random miss fire would indicate many things going on including nothing. this code can occur with just an engine surge in power as the timing sensors are monitored that closely.

    could be water in the fuel . did you check out the engine plugs/fuel pressure check for leak down etc ?
    #10
  11. geo1

    geo1 New Member

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    j cat,i enjoy reading youre input,to the po300,have you seen one go away?on own,my few expierences always needed a relearn,even after problems fixed,input helpful thanks
    #11
  12. j cat

    j cat Active Member

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    yes on my 2000 I had this glitch occur 2 X over the 13 years. In the oem shop manual it actually explains how this can occur with no failures.

    If the engine has a sudden surge in torque it is possible that the timing sensors get out of position for a milli sec and then the p0300 will come on. then the check engine light will stay on for many start cycles before it resets. I twice had to manually reset this and no issues so far.

    I never used the relearn . some have had to use the relearn when replacing the timing sensors but not all.

    It seems that most times this is due to low fuel pressures/low fuel volume. weak pump ,regulator, or not replacing the fuel filters if installed.
    #12
  13. yeevveey211

    yeevveey211 New Member

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    does just the engine light show up for those start cycles or does still misfire?.

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    i disconnected my battery and am going to battery test Tom . simple first. checked my plugs they are all fine Dosent look like they need to be replaced . I Have had no Time to work on her . I also am going to spark test all coil packs to see if hats the problem. I don't have a fuel pressure tester I wish I did to check the injectors .
    #13
  14. j cat

    j cat Active Member

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    auto zone / advance auto should have the pressure gages.
    #14
  15. geo1

    geo1 New Member

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    this is why i am here,my last po300 was solved with a relearn,but not before changing front knock sensor and pig tail harness,02 silverado 6.0 liter,constantly learning here!
    #15
  16. j cat

    j cat Active Member

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    with the KS having a bad connection this would cause the timing to jump creating the 300 code. also this most always will produce the KS code .

    washing the engine usually causes the KS issues. the upper intake was not properly sealed at the factory build. TSB states to seal the front and leave the rear open .
    #16
  17. yeevveey211

    yeevveey211 New Member

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    u know I was thinking about that because up here in photo we only had once very nice day and I washed my truck before work and now it's snow gain son of a b**** I washed it before work and this happens the morning after

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    so your saying take the intake manifold off and check the two knock sensors connections?
    #17
  18. j cat

    j cat Active Member

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    look between the upper and lower intake manifolds at the front of the engine . is the space sealed or open . if open a very good chance this is a problem.

    I had rodents chew on the foam GM used causing this to be open slightly but I caught it before any damage was done.

    I used a silicone based gasket sealer with a foam material . worked the pre cut/shaped foam first then applied sealer to foam and then installed for a very water proof flex gasket . then after the sealer set applied more sealer to the face of the gasket material . so far it is still perfect.

    rodents dont like this stuff around here anyway.
    #18
  19. yeevveey211

    yeevveey211 New Member

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    had checked about half hour ago . no open spaces or gaps.
    but since it's the only nice day for a week or so here I took advantage of it and checked a couple of things for my truck.
    1. battery is good and has good cranking amps and at a solid state
    2.hooked up computer it cleared the p300 code
    3. still knocking . but have good spark through all cylinders
    but I did find a little glitch here when I washed my truck the day before this happneed there is a leak through the weather stripping above the firewall. I took a couple pictures for ya guys

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    sorry lts not turned. but you can see the bent weather stripping and I could see where the water when down on top if the motor.

    Attached Files:

    #19
  20. geo1

    geo1 New Member

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    thanks for tsb info,i left rear foam in,will remove asap,back to po300 on yees v rod,any symptoms?i had none,took a month before k.s. code came up

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    good question,say the vehicle was parked down hill,would water wick thru from rear onto valley?
    #20

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