[Godron629]

Hi Guys,

I have a stock 2003 Astro Cargo Van. When I accelerate from a stop (especially turning) I can hear something rattling from the rear end. A friend thought it was the diff, but I can make it happen by revving slightly in Drive slightly moving.

Shaking the exhaust with my hand, it sounds like something inside of the muffler is hitting the inside walls. It does not seem to hitting anything anywhere along the entire exhaust.

Has anyone had this before?

Do I need to replace the exhaust hanger insulators?

 

[Astrofarian]

Even if the van ISN'T noticeably louder, it could still be the muffler itself. Sometimes, the internal baffles break loose and will cause all sorts of annoying rattles and buzzing noises. Lift up the van and get under the rear of it (Engine OFF) and start swinging a rubber mallet. Chances are, you'll be able to tell where the noise is coming from in less than 5 minutes. Hit the exhaust system, fuel tank, driveshaft, spare tire...anything big and heavy that's hanging down there. Wear gloves and safety glasses while you're doing this; the gloves are in case you MISS, the glasses are in case you hit something filled with grit. Good hunting!
-M!ke-

 

[augidog]

if it's definitely something rattling inside the muffler, smack the bottom of the (cold) muffler rather aggressively, I would use my gloved palm, and ask yourself does it sound like loose sheet metal or like a rock bouncing around.

one worst-case possibility is your catalytic converter may be physically breaking down, and there's a chunk inside your muffler. in severe cases it can have an effect on open-throttle performance by lodging and blocking flow.

if it IS the converter, and I will hope for you that it isn't, you will have to find out why before you replace it. there's plenty of discussion here on the matter, so use search to learn more.

 

[Godron629]

Thanks! I had a video but didn't realize that mp4s aren't allowed.

Here is a video of me shaking the muffer. It does sound like it's coming from something inside the can itself. I did not think that part of the cat might have broken loose. I wondered if there was anything inside the can (stock) but I am not so savvy yet, baffles would make sense.

https://streamable.com/vipmme

 

[Astrofarian]

Hello, again! As Augie said, you could have some chunks from the CAT in there besides/instead of baffles rattling. You might also want to check to make sure that you don't have rocks/pebbles/crud in between that heat shield and the top of the muffler itself. Use an air hose/nozzle if you have a compressor and try blowing air between the muffler and the heat shield. Back to front/front to back. And again, WEAR EYE PROTECTION! Rusty crap will be flying everywhere, you don't want it in your eyes. An N95 mask might not be a bad idea, either. See if that helps any....
-M!ke-

 

[augidog]

that's metal on metal...it sounds like the system's hitting the undercarriage somewhere, have you backed into anything with your tailpipe? yes that's a real thing.

you're not being very aggressive, so if that noise IS for sure INSIDE the muffler, and you'd know better live than us from a video, it's almost a sure bet something internal has rusted loose.

you'd need to sharply strike it as i described to hear a piece of converter rattle around, but I don't think that's your problem.

 

[Leeann_93]

I thought that had happened on my '02, but it turned out to be the muffler heat shield on the body. One of the pop rivets rusted through - a self-tapping screw solved that permanently. On my '93 Bravada, it was the heat shield over the cat.

 

[augidog]

I thought that had happened on my '02, but it turned out to be the muffler heat shield on the body. One of the pop rivets rusted through - a self-tapping screw solved that permanently. On my '93 Bravada, it was the heat shield over the cat.

quite possible...but the gentle back and forth makes it hard to tell. a sharp smacking should result in enough vibration to be sure. boy it's tough to do online exhaust work, eh?

 

[Leeann_93]

quite possible...but the gentle back and forth makes it hard to tell. a sharp smacking should result in enough vibration to be sure. boy it's tough to do online exhaust work, eh?

aka impossible

 

[Godron629]

Thanks for the informative pics!

I personally haven't backed into anything but I just bought it from an electrician with 280k km on it.

I'll giver a good bangin with a mallet in a couple hours and take a better video. I'll also try to get a video of what it sounds like inside the cab.

The heat shield seems pretty tight, but I can see little rocks and stuff around the edges. I couldn't see above it, but rubbed my hand all over the top but couldn't feel any contact.

Maybe it's not even the muffler :lol:

 

[augidog]

aka impossible

:rofl:

 

[augidog]

same piece of pipe you're gently rocking, just smack on it from the bottom with your palm. make it bounce.

I'm still going with the system hitting somewhere, that's exactly what it sounds like. carefully check the tailpipe routing over the axle.

 

[Godron629]

I come bearing videos and pictures

Here are pics of the full exhaust system

I did some wacking around with a mallet but all I heard was me wacking metal.

This is a better (?) video of before. I am smacking the muffer from the bottom with my hand. If you have decent L|R you can locate the sound OK (although the video doesn't show it, hopefully the above pictures show that there is nothing touching above).
https://streamable.com/asmaj6

Here I shake the muffler tip side-to-side from the end, you can hear the same sound, but much less.
https://streamable.com/bxc2dl

However, I got some video of inside the van which I suspect is much more useful. It is the sound right after I accelerate.
https://streamable.com/agylz6
https://streamable.com/u4nlr9

There is also a similar sound when I come to a stop, momentarily where the exhaust (?) is resonating just right. It is quieter and I am not sure it is the same thing I could not get it happen on video - primarily, I am hearing those last two videos (which, the longer I did this, the longer I felt that it wasn't the exhaust :bouncy: ).

(also, this doesn't happen when the van is cold, only after about 15 minutes of driving this starts)

(also, I did get the muffler really moving, bouncing it up and down, but it took two hands. It sounds like a louder version of the video, there was no "free rattling" if I can call it that)

 

[augidog]

that's what I call dedication to the cause. good camera work, I could follow the sound on my chromebook with front-firing speakers. you're doing your part to help.

the system is hanging properly with plenty of clearance. the heat shield appears tight, and I'll assume you've tugged on it to be sure.

if the problem wasn't the exhaust, there'd be no clear metallic clunk, which sounds the same whether you gently move or aggressively bounce it. the vibrating noise when running seems to have the same tone as the clunk. all things considered, it doesn't strike me as a heat shield noise.

mind you, this is only my opinion, but I'll vote internal movement in the muffler. factoring in that the vibrating happens only after warming up, I think it's early stages of a tube loose in a baffle. if forced to bet, I'd go with the tailpipe. it's welded to the end-cap but a press-fit through the baffle, so it's not exactly rare. if there was major rot, I think your exhaust tone wouldn't sound so normal.

you should wait for more best-guesses. you could also take it to an exhaust specialty shop, they won't charge you anything to check it out. if you're planning on doing this at home, OE-equivalent replacement (muffler & tail) isn't difficult, so long as you have what it takes to work with the studs. it looks like yours might zip right off with an impact wrench.

knowing (?) what it is, and you haven't mentioned poor performance, you could drive it until it gets so bad you can't stand it or until leaks occur.

that was some long-winded editing, but you've put the time into some good posts, so...there ya go.

plus, my first cup of coffee is always really strong and there's nobody in chat yet :blah:

 

[Godron629]

Ok, I will ask around at muffler shops for an appointment.

Quite honestly the performance is less than stellar, but I didn't comment on it as I have never owned similarly typed vehicles to compare it to.

I am consistently the slowest out of a red light, have never had the thing wide open but it will cruise decently at fast highway speeds. That being said, I am quite gentle starting off as (another problem) I have a hard shift from 1-2. I have a new accumulator but I'm waiting on a new oil filter and oil if I'm gonna have it all apart.

Maybe this is my segway into the straight rumble gang, or maybe at least just the new muffler gang. Being real, the sound is not so bothersome - not knowing what it is, is :think:

(I make a lot of edits, too - there are always so many smal errors)

 

[MechBob]

Needs a new chrome muffler bearing.

 

[sixsix]

First off - welcome to the Forum. Interesting problem.
A few observations and maybe a good idea...

- First - GET RID OF THOSE RAMPS !!

 

[sixsix]

First off - welcome to the Forum. Interesting problem.
A few observations and maybe a good idea...

- First - GET RID OF THOSE RAMPS !!

OK, got that out of the way. I might suggest looking for a set of "old school "Heavy Metal" ramps.

Maybe they are loaners, not yours - cool. If you do get some of your own... hold out for above.
Or do the "Jacks and Stands-Bingo Jump around Ordeal ( the actual tech. term-aka JasBiJao ).
And if you want a pic, I'll look, I have one around here somewhere.



- that sound does not sound like muffler at all - We have the "Tail Pipe Bump noise" in The Van.
Seems it has always had it and it IS exhaust pipe, tailpipe related.

Does not sound like yours. It sounds more like sheetmetal vibe, when throttling down. Which has a tendency to find ANY noise.
Like Bad RR tracks, if there is a pitch spacing to a few sets.

Been here 6 years, listened to a lot of video, audio dealeos - I have NEVER heard your noise type, volume, clarity, etc.
Then there is trans/flexplate... I dunno'.

And you have posted probably the best first set of pics and videos EVER here. I have been told that I exaggerate a bit, tho...
Come right up, orientation perfect, even land. vs port. mode pic taking is spot on.
Nice!

Could someone rule out Fuel Pump... ? W/O going back to your OP, has it ever made the sound when sitting still ?

When you do get to that shop - don't just let them have it. Force them to ride w/ you. Shops can be dicks... right.

 

[dcsleeper]

That's a flat-ish piece of metal like a heat shield. I can tell by the sound. check the one ON the muffler.
You can excite the metal by putting a bare loudspeaker against it, playing bass music.

 

[augidog]

(I make a lot of edits, too - there are always so many smal errors)

hey...did you do that on purpose?