Catalytic Convertor Rattle

KirkA · April 21, 2020

Noticed the other day a rattling noise coming from the right side. Sounded like it was coming from my trans. Got up under it and had a friend rev the engine. As the engine revs up/down, it will just make this vibrating/rattling sound at just a certian frequency. Does it sitting still or driving. Most noticable when I stop and start. Pretty sure it is the Right catalytic convertor. Occasionaly I get a CEL and when I check it, it will be the P0420 code. The CEL comes and goes, so I figured that the CC was about to go, now this. Strange thing is, even with this rattle, there is no CEL on right now and its been doing it for about a week. I have 247k miles on my truck and I bought it brand new, so I know these are factory cats in there.

question is:

1. Should I just gut the CC? If I do will I not get a CEL because the cat is not working correctly?

2. Replace just the CC with an aftermarket weld-in CC? What is a good brand to get that will last? What about these from ebay

3. Other options to fix the rattle??? could I just cut it apart and figure out whats rattling? Maybe fix the rattle and reweld it back together?

Just trying to weigh my options.

Thanks,

CamGTP · April 21, 2020

I would get under there with a rubber mallet and just start bopping stuff to see where the noise is really coming from.

If you are getting random P0420 or P0430 codes, then the cats are likely on their way out at this mileage.

Removing or gutting the cats will cause a check engine light and depending on the year it will trip a post o2 sensor test and a cat test itself. Those tests could reduce fuel mileage because the computer will be trying to see if the cat is still working by adding additional fuel to see a change in the o2 sensor readings.

I would either see if you can find a good take off unit from someone selling one or I would just by a new aftermarket Y-pipe with cats. I won't be a sales man for Walker products but I've yet to have a problem with their cat converters yet in various applications. Bought them all from Napa.

swathdiver · April 23, 2020

On 4/20/2020 at 11:27 PM, KirkA said:

Noticed the other day a rattling noise coming from the right side. Sounded like it was coming from my trans. Got up under it and had a friend rev the engine. As the engine revs up/down, it will just make this vibrating/rattling sound at just a certian frequency. Does it sitting still or driving. Most noticable when I stop and start. Pretty sure it is the Right catalytic convertor. Occasionaly I get a CEL and when I check it, it will be the P0420 code. The CEL comes and goes, so I figured that the CC was about to go, now this. Strange thing is, even with this rattle, there is no CEL on right now and its been doing it for about a week. I have 247k miles on my truck and I bought it brand new, so I know these are factory cats in there.

question is:

1. Should I just gut the CC? If I do will I not get a CEL because the cat is not working correctly?

2. Replace just the CC with an aftermarket weld-in CC? What is a good brand to get that will last? What about these from ebay

3. Other options to fix the rattle??? could I just cut it apart and figure out whats rattling? Maybe fix the rattle and reweld it back together?

Just trying to weigh my options.

Thanks,

Ba wary of Chicom cats Kirk. Someone installed one on mine right before I bought my truck and it failed inside of six months. Replaced the whole Y-pipe with a Magnaflow setup, better piping and cats are high flow. When they fail, I'll gut them out and have the downstream sensors turned off in the tune.