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truck knocks on startup :/

Discussion in 'GM Powertrain' started by quicksilver8817, Dec 27, 2011.

  1. quicksilver8817

    quicksilver8817 New Member

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    1990 k1500 .. 350 knock for about 25 seconds upon startup and the the knock goes away .. would really like to know what the issue is ..?
    #1
  2. Boonduff

    Boonduff New Member

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    How many miles on the motor? Could be worn bearings.
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  3. quicksilver8817

    quicksilver8817 New Member

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    185000 on the odomoter i dont know how much on the actual motor
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  4. Boonduff

    Boonduff New Member

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    The knock is most likely caused by excessive bearing clearances. The only way to tell for sure is to pull a bearing cap and check.
    #4
  5. quicksilver8817

    quicksilver8817 New Member

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    as that a big project ... i just tore apart my front differential to change the clips that hold the spindle shafts in place and that was a big project. i just cannot afford another big project at the moment ..
    #5
  6. quicksilver8817

    quicksilver8817 New Member

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    my buddy told me the oil filter may be too restrictive and not allowing oild to enter as quickly as it should
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  7. maasmania

    maasmania New Member

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    this happens to mine as well. but chevrolet says as long as it goes away then it shouldnt damage anything. mines done it since 30k and im about to hit 190k with no issues. its worse in the cold correct?
    #7
  8. Corso

    Corso New Member

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    What Chevy doesn't? :lol:
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  9. Boonduff

    Boonduff New Member

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    A Dealer told you that? Please tell us which one so they can be avoided. Lifter clatter is common on cold mornings but rod or main bearing knock means a badly worn motor.
    #9
  10. Corso

    Corso New Member

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    Rod or main bearing knock wouldn't go away after 20 seconds.
    #10
  11. maasmania

    maasmania New Member

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    the dealership here isnt the only one that tells customers that, they extended the warranty by 25k miles. but its done it for 8-9 years now and nothings gone wrong with the motor so i believe em.
    #11
  12. grape2

    grape2 New Member

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    I agree with CORSO, I thought that was a trait. My knocks of start up also. If the filter is not 2 stage (orange mostly) all oil drains back and allows knocking on start up. I have changed from the orange filter to GM or MOPAR and the knocking goes away. As a service manager, I called the factory hotline about a knock and they asked if it has an orange filter on it not to call them until I changed the filter and rechecked for a knock.
    #12
  13. Corso

    Corso New Member

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    Interesting info regarding filter types, that is new to me. What is considered an "orange filter", a Fram? I just had my Silverado's oil changed last Tuesday at the dealer. I would think they are using AC Delco filters. Engine still knocks/clatters/whatever you want to call it upon cold start up.

    When I had my TBSS I did the oil myself always using Mobile 1 and Delco filters and it too did the same. My Suburban currently has a Delco filter in it and it makes all kinds of racket upon cold start up. The 2 454s I had in my Formula offshore boat always had either Mobile 1 filters or WIX filters, and guess what? You guessed it....knock on cold start up.

    Like I said earlier, a GM pushrod motor that does not knock upon cold start up is an anomaly. It's the nature of the beast.
    #13
  14. grape2

    grape2 New Member

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    I have used Mobil 1 for years until I switched to Valvoline syn oil. In my Dodge the knock went away on start up, I have noticed this with Mobil 1 in other cars I owned and other poples cars. Chrysler always stated to install a filter with a check valve so the oil would not drain back overnight. Orange is Fram, this list we had to choose from was Wix, Napa (they are the same), Mopar, Ac delco, Puralator and two or three more that I can't think of. Around here the orange filter was not sold for years, just making a comeback in the late 90's early 2000. I use the Mobil filter when I use Mobil1 and Puralator with valvoline. Never had a problem with Mobil1 except start up knock, and no problems with valvoline. I have not performed an oil change on the Suburban but have 5 qts of Mobil1 on the shelf, but not sure if I will use it or switch.
    #14
  15. Corso

    Corso New Member

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    Yeah, Fram is unchartered waters for me as I have never used one due to their reputation as being junk.
    #15
  16. My98Suburban

    My98Suburban New Member

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    My Suburban Has 180,XXX miles on it Mine does the same on start-up when its cold its alot worse.I think its lifters seems to clanking/tiny to be mains and it goes away after 20-30 seconds...I always thought if it was main bearings it would have a low clunk clunk at idle and deosnt go away like mine does now...I have an AC delco oil filter and 10-30w oil in it...
    #16
  17. quicksilver8817

    quicksilver8817 New Member

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    yes it is more prominent when its colder .. i like in ohio and its 15 degrees here now .. my truck also has the factory oil cooler that goes to the radiator idk if that would make any difference ..
    #17
  18. zachh1020

    zachh1020 New Member

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    I have the same problem in my 2003 Silverado with 163,000Mi. Piston Slap maybe?
    #18
  19. gaborn73

    gaborn73 New Member

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    thanks to everyone for the great info in this thread. I performed a seafoam clean out of my block in the summer and the knock is in the head/lifters. does this sound like everyone else's noise?
    #19
  20. Corso

    Corso New Member

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    Yes, it's in the valve train, not the bottom end.
    #20

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