"rattling noise” from Catalytic
 

Hello,
I was wondering if anyone ever experience “rattling noise” coming from Catalytic converter? You can only hear it after engine is fully warm and noise stops after about 2000 rpm. Also it is a lot more laud if truck is in gear and under a load.
(I have a 4Runner 1996 4x4 (automatic) with 88 000 miles on it.)
Heat shield on cat doesn’t appear to be moving at all. I did try to push on catalytic from the bottom passenger side while engine is running and I am getting less noise that way. And what strange to me that I never heard fro anyone that catalytic can make rattling noise not like mufflers anyway.

Does it look like I will need a new Catalytic very soon?
Thank you.

I have an '88 and I was getting this rattling worse and worse. One day when doing highway driving I starting losing power slowly but surely. It got so bad I had to downshift to 4th to keep any momentum.

I limped it home and took the exhaust apart. Looked in the cat and the metal matrix had come completely loose, turned sideways, and lodged into the back of the cat housing effectively choking the truck.

I used a crow bar to bash the matrix to pieces and literally pour it out of the cat. Truck runs great now, but obviously I need a new cat for environmental reasons.

Its either the internals are cracked/broken or a heat shield is loose. Crawl under whrn its cold and jiggle the heat shilds, if they don't move give it a thump with your fist. Sound like a rock in a tin can? Need a new one then.

CatCos are only $30-50.

Lamm

Thank you for all info!
Where can I get it for $30-50?

I got mine from a local muffler shop, but Summit racing sells them for $50.

Lamm

If it's just an issue of a loose heat sheid, I'd suggest investing a whopping .05-.06 cents in some 1/4"-3/8" self-tapping sheet metal screws and a little time under your ride with a cordless driil to permanently repair that loose sheid from where it's welds popped loose.:great:

Yep. My cat started rattling after it smacked a rock. I figured I'd let it rattle forever but then it started clogging up the exhaust system and I had to replace it. Mine was about $60 installed (welded in) at the local muffler shop.

Does anyone have any info on High Flow Cats? Are they worth the money or just another rip off? Thanks Bryan

High flow cats are actually higher flowing. Many good high flow cats like Carsound Magnaflow Cats, flow very good and at the same time help keep the earth green. I noticed that when I still had my turboed Civic I only lost a few hps with the Carsound cat in. One thing that I really notice was that the cat controlled the sound of the exhaust. When I had the cat in my Civic was whisper quiet and the exhaust note was deep with no back firing. Without the cat at some rpms it sounded like a crazy derange bumble bee.

i had the same problem with my truck only mine is a manual, every time i downshifted and the rpm hit 2000 i would get an ugly metallic rattling sound from underneath my truck, and also when i just revved it past 2000. but now i have a magnaflow high flow cat and the noise is completely gone. now my truck doesn't sound like crap

i had an S10 that'd make a god awful rattle when idling high. definitely your cat.

I had the rattling noise and replaced
My cat today and the noise is still there. Any suggestions?

Turn the truck on and see if the exhaust is hitting anything that would cause it to sound like a "rattle"... My rattling sound coming from my exhaust is my cat, but I choose not to worry about it for now.


P.S. I'll go easy on ya because you're new to the forums, but PLEASE don't bump old threads... Either search for your answer or start a new thread in the appropriate category ;)

I had the vibration dampener on my exhaust rust and fall off, and at idle but in gear I get a nasty rattle. I had some one put it in gear with the brakes on and I got underneath to investigate, after I held the exhaust right where the dampener used to be the rattle went away. Check to see if one or more of those dampeners has fallen off, maybe an exhaust shop would sell and weld one on for you if that's your problem. Welcome to YotaTech! :great:

Where do you find an installed catalytic converter for $60?
 

If you go back in time to 2005, you can find great deals!

Seriously though, if you go with Rock Auto or some other place to buy aftermarket parts, it's a lot cheaper. I bought my cat on Rock Auto for under $300, then installed it myself, but it's a quick, easy job for an exhaust shop. Shouldn't be more than an hour labor. It's better not to go with the cheapest you can find, but I think it's ok not to go OEM with a cat.

On my 2008 4Runner, it had a terrible rattle at idle. I got a big stainless strap like they sell for dryer hoses and clamped it. It only cost about $4. I think I got it at O'Reilly's.