exhaust rattle, and I can't locate it

[stumpjumper]

2002 box s

so I've got a rattle, unmistakable metal rattling sound, that I can hear bouncing off walls and whatnot when accelerating or decelerating, but only when there's resistance (it doesn't happen in neutral when stopped, I can only hear it when moving and in gear)

so I put the car up on ramps and thought I found the rattle in the rear most passenger side cat heat shield so I removed both the rear cat's shields, screws, and the clips they screw into

turns out this was making some noise, but not the one I heard :(

are there shields around the forward cats too? or maybe the headers? I haven't put the car back up to look but every time I drive I hear this and it's bugging me!

Edited June 8, 2007 by stumpjumper

[eheaiel]

I also had a wicked rattle that I couldn't find. After checking all of the usual suspects, I took my time and examine every surface, joint and nut. After 15 mins I found that there was a crack in the bracket on the cat that connects to the extension arm coming from the exhaust. I was completely severed, I had to look closely and shake it with my hand to see any movement.

Mark

2002 box s

so I've got a rattle, unmistakable metal rattling sound, that I can hear bouncing off walls and whatnot when accelerating or decelerating, but only when there's resistance (it doesn't happen in neutral when stopped, I can only hear it when moving and in gear)

so I put the car up on ramps and thought I found the rattle in the rear most passenger side cat heat shield so I removed both the rear cat's shields, screws, and the clips they screw into

turns out this was making some noise, but not the one I heard :(

are there shields around the forward cats too? or maybe the headers? I haven't put the car back up to look but every time I drive I hear this and it's bugging me!

[stumpjumper]

yuck

time to go back under the car!

[Glyn]

yuck

time to go back under the car!

Quite common for the baffle inside the exhaust box to become detached and rattle

[ocblubox]

2002 box s

so I've got a rattle, unmistakable metal rattling sound, that I can hear bouncing off walls and whatnot when accelerating or decelerating, but only when there's resistance (it doesn't happen in neutral when stopped, I can only hear it when moving and in gear)

so I put the car up on ramps and thought I found the rattle in the rear most passenger side cat heat shield so I removed both the rear cat's shields, screws, and the clips they screw into

turns out this was making some noise, but not the one I heard :(

are there shields around the forward cats too? or maybe the headers? I haven't put the car back up to look but every time I drive I hear this and it's bugging me!

There is a sleeve wrapped around the pipe of the cat that corrodes at the welds. I removed mine with tin snips after the OK from the OPC mechanic, otherwise it's new cats

[stumpjumper]

both of those scenarios sound wonderful...

yay for 1 more year of CPO

[alstarz88]

had th same problem with mine when i went underneath i saw the stud and bolts that go between the cats and the manifolds had rusted away quite common apparently sounds fine on idle rattles when accelerating also check heat shields on the exhaust the bolts on those have he same problem

[Tom C]

I'm having the same problem. Found a rusted loose bolt on top of the right cat shield and thought I had found the problem. Still rattles when accelerating. I'll keep looking and feeling...hopefully one of us will find the source.

[stumpjumper]

ok so a little update

the heat shields weren't it, so I got annoyed and started whacking the hot exhaust with a rubber mallet, narrowed the rattle down to the passenger side cat/elbow for sure, but it was still too hot to touch so I let it sit and was going to come back and put it on ramps to search

to my dismay it won't rattle when it's cold!

tonight I'll try again, putting it up after the drive home and searching better, if I find anything I'll take pics... now where's that oven mit

[stumpjumper]

OK, it's 100% surely the rear passenger side cat, it appear to be the sleeve that ocblubox mentioned

[Tom C]

That seems to be it, I bent the right cat heat sheld up and spread it slightly which stopped about 90% of the rattling. Thanks to everyone for your input and help.

[stumpjumper]

I found my rattle, and I killed it

around the rear cat, on the side where it has the 70ish degree bend, there are 2 pieces of steel welded around the bend, these pieces float around the pipe and are only welded to the canister, using a rotozip and a metal cutting wheel I cut through the welds and removed these pieces, the canister and pipe are still 100% intact

the weld on the inside of the bend (the smaller weld) was broken, and this is what would rattle as it heated up, now there's no rattle at all and the car sounds very different... I forgot what it was supposed to sound like

[ocblubox]

I found my rattle, and I killed it

around the rear cat, on the side where it has the 70ish degree bend, there are 2 pieces of steel welded around the bend, these pieces float around the pipe and are only welded to the canister, using a rotozip and a metal cutting wheel I cut through the welds and removed these pieces, the canister and pipe are still 100% intact

the weld on the inside of the bend (the smaller weld) was broken, and this is what would rattle as it heated up, now there's no rattle at all and the car sounds very different... I forgot what it was supposed to sound like

Glad to see you sorted the problem. It also took me a while to figure out it was those shields

[stumpjumper]

Glad to see you sorted the problem. It also took me a while to figure out it was those shields

well had you not made your post I'd have been stuck, so thanks to you I found it and fixed it!

[Stefan]

I had the same problem. I initially made the problem go away by bending the metal so that the heat shield didn't have space to rattle. But it eventualy found a way to rattle again. So I removed the shields from both sides and replaced them with cloth heat wrap. I will never have that problem again and the exhaust is probably better insulated than stock.

[Tom C]

I had the same problem. I initially made the problem go away by bending the metal so that the heat shield didn't have space to rattle. But it eventualy found a way to rattle again. So I removed the shields from both sides and replaced them with cloth heat wrap. I will never have that problem again and the exhaust is probably better insulated than stock.

Stefan, see post 11, the same thing happend to me. Everything was ok for about two weeks, now the rattle is back and as bad as ever. Can you add a photo of how you installed the heat wrap. Did you wrap the cats or mold a shield with them over the cats? Where did you purchase the wrap. Any help you give would be appreiciated. I thought I had found another source, a bar running directly behind the muffler was rattling a little I bent it downwards but that didn't help.

[uabchris]

ok so a little update

the heat shields weren't it, so I got annoyed and started whacking the hot exhaust with a rubber mallet, narrowed the rattle down to the passenger side cat/elbow for sure, but it was still too hot to touch so I let it sit and was going to come back and put it on ramps to search

to my dismay it won't rattle when it's cold!

tonight I'll try again, putting it up after the drive home and searching better, if I find anything I'll take pics... now where's that oven mit

I am having the same problem on my 00 Boxster (149K) and the dealer told me the cat on the right header was coming apart on the inside. Mine sounds like loose valetrain below the side air intake. SO now the question is buy 1 factory header at $1200 (2 yr warr.) or fabspeed set $2400 (lifetime warr.)

cheers,

Chris

[meko19]

What is/are the 'cat' that is referrenced to in this post? Is it referencing the catalitic converter? Thanks!

[Loren]

What is/are the 'cat' that is referrenced to in this post? Is it referencing the catalitic converter? Thanks!

Correct.

cat = catalytic converter , also know as TWC Three Way Catalytic converter.