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  1. #1

    Default Catalytic Converter Help

    well i think it might be my cat but not too sure.. just help me out here because its a little hard for me to explain

    well when ever i start it up after 10 15 seconds after the revs go down from starting it you can hear a rattling sound comming from the the passenger side in between the cab and the bed. it sounds like if you got sand and put it in a aluminum container and shake it. it also makes that sound when you lightly lightly press the gas you hear it or when your going in reverse very slow with the gas but if you just sleightly give a more gas it goes away both in reverse or in drive.
    i took it to a mechanic he said it my be my catalytic is clogged but if that was the case wouldnt it be throwing a code out and my truck has no lights going off in the dash.

    ---------- Post added at 11:58 AM ---------- Previous post was at 11:57 AM ----------

    but i think its that big drum of the muffler thats make that noise but not too sure what do you guys think it is?
    2003 Silverado Extended Cab
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  2. #2
    murdog94's Avatar
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    Sounds more like your heat sheilds have had it. I would start there. Or else you have a rock stuck between the heat shield and the cat...
    That is where i would start. And theoretically you would get a code for a plugged cat but it isnt a gurantee.


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  3. #3


    From what you have mentioned.....and not been able to hear the sound.....I'm guessing here.....

    A few months back I had a Metallic Sound,coming from under my truck.....My first thought was a Cat is going out......But No code....2nd the sound was Only present went on the Gas...

    Finally able to pin point the was the Starter.....the motor in the starter was not Dis-engaging,after start up.......and was hitting teeth on the fly wheel.......Put in a New starter....No more sound......Like I said I'm taking a guess....
    Last edited by 99'HEARTBEAT; 07-31-2010 at 02:33 PM.


    5.3 l 3.73 l G80

  4. #4


    what do you mean maybe a rock in between??

  5. #5
    murdog94's Avatar
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    Like you got some dirt into the space between the heat shield and the cat... There is about 1/4in gap between the shield and the cats.

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