2007 silverado 1500 rattling cat

[pottss55]

thought i had the dreaded cold start piston slap but discovered it was left side cat rattling internally on cold starts only makes noise for about 30 seconds. head pipe has been down 3 times due to transmission issues.. my question is if i gut the cats out will it damage anything or throw out codes ?I understand legal the ramifications ,just didn't want it to break up and plug up.

[gmtech1]

Yes. It will set a cat efficiency code and/or 02 sensor codes. You will also fail emissions testing if you have them in your area.

[j cAT]

Originally Posted by pottss55

thought i had the dreaded cold start piston slap but discovered it was left side cat rattling internally on cold starts only makes noise for about 30 seconds. head pipe has been down 3 times due to transmission issues.. my question is if i gut the cats out will it damage anything or throw out codes ?I understand legal the ramifications ,just didn't want it to break up and plug up.

most times that rattle is the outer skin. get some steel wire and wrap around the skin see if it is reduced or gone.. if it works buy some stainless steel wire to make sure it will last...

[pottss55]

thanks for responses , there isn't any heat shields on cats just the solid can of the cat. Have been under truck when starting and can hear rattling inside of cat , hate noise but not ready to dump 300 on new headpipe