Low RPM knocking...
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Cadillac STS Forum - 2005 through 2012 Discussion, Low RPM knocking... in Past Cadillac Vehicle Discussion; I have an '05 STS, with just under 60K miles...has always been good to me. However, over the weekend the ...
  1. #1
    kelprod is offline Cadillac Owners Member
    Automobile(s): sts
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    Low RPM knocking...

    I have an '05 STS, with just under 60K miles...has always been good to me. However, over the weekend the engine started a rapid tapping at low RPM's during acceleration and also during deceleration...at about 2,000 rpms. The sound makes the car sound like a diesel engine, only not as loud. Any ideas???

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  3. #2
    1BadCadSTS's Avatar
    1BadCadSTS is offline Cadillac Owners Connoisseur
    Automobile(s): 05 STS4
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    Re: Low RPM knocking...

    I noticed when I start my 05 V8 cold it will do this, its part of the VVT (at least thats what the dealer said).
    First I would check the oil level and make sure its proper.
    Second you make no mention if you have the 4.6 V8 or the 3.6 V6.
    Make a video of the sound if you can as well?

  4. #3
    kelprod is offline Cadillac Owners Member
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    Re: Low RPM knocking...

    It is a V6....and the sound is driving me NUTS! It only happens when I accelerate from a stop position or I am slowing down to a stop. It does not happen during an idle or at speeds above 2,000 rpm's....

  5. #4
    mckellyb is offline Cadillac Owners Enthusiast
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    Re: Low RPM knocking...

    Does it change in sound/intensity as the engine warms?

  6. #5
    EChas3's Avatar
    EChas3 is online now Cadillac Owners Master
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    Re: Low RPM knocking...

    Certain 3.6 engines were subject to stretched cam chains & others to camshaft issues. Either could be the source of your noise. I think one member had a tapping noise coming from the top drivers-side rear area of an engine but I can't remember if it was the 3.6.

    Oil level is very important to both engines and some members have reported sudden increases in oil usage with the 3.6. GM really should have set the oil-level warning at one quart low.

    Do you have a warranty?

  7. #6
    AllGoNShow is offline Cadillac Owners Enthusiast
    Automobile(s): 05 Cadillac STS V6
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    Re: Low RPM knocking...

    I have the same noise on my V6, drove me nuts forever. Haven't done a timing chain yet so not sure if that will fix. Definitely valvetrain noise from something. Been going on mine for about 40k, no change.

  8. #7
    Caddy4L is offline Cadillac Owners Member
    Automobile(s): 05 Cadillac Sts
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    Re: Low RPM knocking...

    Did anyone find a solution to the low rpm knocking? Just started happening to me in my 05 sts v6. I have no clue what it could be

  9. #8
    SC2150's Avatar
    SC2150 is offline Cadillac Owners Connoisseur
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    Re: Low RPM knocking...

    Usually what it sounds like when a rod bearing is going on these. At lower rpm's with a lite load, just give it a bit of gas and listen....you should be able to duplicate it., let off the gas and it should go away. Step on the gas lightly again and it should come back. Catch it in time and you may save the crank. Do timing chain set at the same time.
    RX Performance Products/RevXtreme.com 941-721-1826

  10. #9
    Cadillac Cust Svc's Avatar
    Cadillac Cust Svc is offline Cadillac Customer Service
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    Re: Low RPM knocking...

    Quote Originally Posted by Caddy4L View Post
    Did anyone find a solution to the low rpm knocking? Just started happening to me in my 05 sts v6. I have no clue what it could be
    Hello Caddy4L,

    I see that you have gotten some great advice from the community regarding the noise in your STS. If you are concerned with the sound and would like to take your vehicle into the dealership to have the dealership look into this concern, feel free to private message me so I can assist you in working with the dealership. If you are unable to private message me, you can also send me an email to socialmedia@gm.com with the subject line as “ATTN GREG” so that it gets delivered straight to me. Thank you very much for your time.

    Gregory W.
    Cadillac Customer Care

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