Help with Exhaust Rattle- Bad gasket?!

[Berty_K]

Recently started hearing a rattle at low RPM, near idle. Intermittently hear it when I’m starting from a stop or I’m in drive and stopped.

Sound has a bit of a metallic sound to it.

Crawled under my car and checked for any loose heat shields and hangers, but couldn’t find any.

Started knocking on the exhaust pipe and found the sound seemed to be coming from passenger side of the exhaust, near the front and rear catalytic converters. No loose heat shields or loose mounts.

Looking closer at the joint between the two passenger side cats, there seems to be a gap (picture below). Is it plausible that the gasket that goes between the two sections of the exhaust disintegrated and is causing the rattle?

Hoping the gasket is the culprit. They’re cheap and should be a relatively simple fix. I don’t think my cats are the cause of the rattle. I don’t have any dash lights (cel) that would indicate my cats aren’t functioning correctly.

 

[Zero0575]

Recently started hearing a rattle at low RPM, near idle. Intermittently hear it when I’m starting from a stop or I’m in drive and stopped.

Sound has a bit of a metallic sound to it.

Crawled under my car and checked for any loose heat shields and hangers, but couldn’t find any.

Started knocking on the exhaust pipe and found the sound seemed to be coming from passenger side of the exhaust, near the front and rear catalytic converters. No loose heat shields or loose mounts.

Looking closer at the joint between the two passenger side cats, there seems to be a gap (picture below). Is it plausible that the gasket that goes between the two sections of the exhaust disintegrated and is causing the rattle?

Hoping the gasket is the culprit. They’re cheap and should be a relatively simple fix. I don’t think my cats are the cause of the rattle. I don’t have any dash lights (cel) that would indicate my cats aren’t functioning correctly.

The gasket does look a little off. Start the car and roll underneath there. Put your hands around that joint (obviously without touching it and burning yourself). Can you feel air escaping? If so, then replace it.

It might be your issue - I recently had the same problem, but also had a rusty rear muffler. I replaced that gasket and put a new catback on at the same time and no longer have the rattle. I can't confirm that it was the gasket or rusty muffler or maybe both, but changing out that gasket is a cheap start. Around $5 after shipping:

More Information for BRE 256214

 

[Berty_K]

The gasket does look a little off. Start the car and roll underneath there. Put your hands around that joint (obviously without touching it and burning yourself). Can you feel air escaping? If so, then replace it.

It might be your issue - I recently had the same problem, but also had a rusty rear muffler. I replaced that gasket and put a new catback on at the same time and no longer have the rattle. I can't confirm that it was the gasket or rusty muffler or maybe both, but changing out that gasket is a cheap start. Around $5 after shipping:

More Information for BRE 256214

Thanks for the reply! Tried feeling for a leak this in the morning and couldn't feel anything.

I'm hoping the cats aren't the issue. They're pricey.

Have a gasket on order. Going to give it a shot this weekend.

 

[sundance21]

If the joint is tight, it's probably the cat. I don't see how that joint could be rattling. Squeaking. Maybe.

 

[Berty_K]

If the joint is tight, it's probably the cat. I don't see how that joint could be rattling. Squeaking. Maybe.

Yup- the sound is more of a squeak than a rattle. Hoping it's just a gasket.

 

[UrbanRunner651]

check the welds at the top of your cats to the tabs that act as hangers. One of mine developed a hairline fracture that was almost invisible to the naked eye & caused rattle when in gear. I found it by listening to it running and then tapping along it cold and checking all the welds.
The weld union at the front & rear of the muffler is also prone to crack with rust like whats shown in your pic. Sometimes they just crack and don't completely separate so you only hear it at certain RPM, gear or moving certain directions.

 

[Berty_K]

check the welds at the top of your cats to the tabs that act as hangers. One of mine developed a hairline fracture that was almost invisible to the naked eye & caused rattle when in gear. I found it by listening to it running and then tapping along it cold and checking all the welds.
The weld union at the front & rear of the muffler is also prone to crack with rust like whats shown in your pic. Sometimes they just crack and don't completely separate so you only hear it at certain RPM, gear or moving certain directions.

This is super helpful. Did you end up needing to replace your cat because of the fracture?

 

[UrbanRunner651]

I had actually had both replaced when I had my headers put in almost exactly a year prior. I took it back to the shop that did the work and they welded it back free of charge.
If you aren't getting codes that indicate a foul/clogged converter or leak in the system then you should be fine keeping the cats and just fixing the weld.
If that's what your problem actually is..

If you still can't find anything, find a good exhaust shop & ask for an inspection. They'll typically run a stethoscope over the tops of the pipes and along the welds to listen for escaping air while it idles for free.

 

[Berty_K]

I had actually had both replaced when I had my headers put in almost exactly a year prior. I took it back to the shop that did the work and they welded it back free of charge.
If you aren't getting codes that indicate a foul/clogged converter or leak in the system then you should be fine keeping the cats and just fixing the weld.
If that's what your problem actually is..

If you still can't find anything, find a good exhaust shop & ask for an inspection. They'll typically run a stethoscope over the tops of the pipes and along the welds to listen for escaping air while it idles for free.

Lots of great information. Thank you!

 

[Berty_K]

check the welds at the top of your cats to the tabs that act as hangers. One of mine developed a hairline fracture that was almost invisible to the naked eye & caused rattle when in gear. I found it by listening to it running and then tapping along it cold and checking all the welds.
The weld union at the front & rear of the muffler is also prone to crack with rust like whats shown in your pic. Sometimes they just crack and don't completely separate so you only hear it at certain RPM, gear or moving certain directions.

CAN I BUY YOU A BEER?!

There’s a hairline fracture on the bracket (Toyota PN 17118-31030) that holds the Cats.

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[UrbanRunner651]

WINNER WINNER CHICKEN DINNER! lol

Just glad you found it man! I know how much it bothered me until I got it figured out.