Weird Noise from underside....

[lowpost99]

Mostly when 2001 LT Tahoe 5.3 is in a low speeds like parking lot speeds, in reverse, and pulling off, sometime even just my foot on the brakes, I have a resonating sound that seems to travel from front to rear. I suspect it is exhaust/muffler related, (I am still on the original muffler but no emission test issues) and I've tried to strap down the y-pipe, but it still has this noise. The noise doesn't occur when I'm higher than 15-18mph. Some have suggested that its heat shields and that I should remove them but I dont have any idea on how or where to access them. I went to a shop and the guy there says that he and his bnl have the same issue and haven't been able to locate the source of the noise. I was once told that the muffler has internal fins that can come loose and that compressing the muffler a just little bit could help.

Any ideas?

 

[Z28TWITCH]

Turn the radio up But seriously, without being in/around it, impossible to say for certain.

 

[MrBalll]

Hard to say.
As far as the shop it sounds like he really didn't want to look for it. His and yours are different rides so that's not fair to say.
You may try going to another shop or just see if you can lay in the back seat and stick your head out the door and just listen as someone drives. Try and figure out where the noise is coming from.

I'd almost guess it's an exhaust issue based off the speed limit thing. You could always put something heavy on the muffler or tighten the holds for the exhaust system and see if it helps. If it were me, and I'm no expert, I might just put a wet rag on top of the muffle to kind of weigh it down and possibly shift the noise to see if it is involved.

 

[lowpost99]

Hard to say.
As far as the shop it sounds like he really didn't want to look for it. His and yours are different rides so that's not fair to say.
You may try going to another shop or just see if you can lay in the back seat and stick your head out the door and just listen as someone drives. Try and figure out where the noise is coming from.

I'd almost guess it's an exhaust issue based off the speed limit thing. You could always put something heavy on the muffler or tighten the holds for the exhaust system and see if it helps. If it were me, and I'm no expert, I might just put a wet rag on top of the muffle to kind of weigh it down and possibly shift the noise to see if it is involved.

Hard to say.
As far as the shop it sounds like he really didn't want to look for it. His and yours are different rides so that's not fair to say.
You may try going to another shop or just see if you can lay in the back seat and stick your head out the door and just listen as someone drives. Try and figure out where the noise is coming from.

I'd almost guess it's an exhaust issue based off the speed limit thing. You could always put something heavy on the muffler or tighten the holds for the exhaust system and see if it helps. If it were me, and I'm no expert, I might just put a wet rag on top of the muffle to kind of weigh it down and possibly shift the noise to see if it is involved.

 

[lowpost99]

Here's the noise listen for the rumble around 0:05 seconds...

 

[iamdub]

Still difficult to tell. But based on your first post, I'm leaning towards loose or broken heat shield or baffle inside muffler.

Try putting it in D, holding the brake firmly so it doesn't move and slowly giving it throttle up to around 2,000 RPM to see if it's RPM/load- and not speed-dependent.

If it still does it, let the exhaust cool then beat around on the muffler and catalytic converter(s) with your fist or a rubber mallet wrapped tightly in a towel or T-shirt to listen for rattles. Make sure all the heat shields are secure.

 

[lowpost99]

Would you have any idea on where to access the fasteners or screws for the heat-shields? In fact, where the heat-shields themselves are exactly?

 

[iamdub]

They're usually riveted to the underside of the cabin floor. I don't know their exact positioning, but you can slide under there and see them. They're just thin metal sheets riveted or bolted to the floor above the exhaust piping and muffler and are usually curved downward, away from the floor, to arch over the piping.

Sometimes they can vibrate loose and rattle against the exhaust. There are shields around and over the transmission that can do the same. Just grab them and give 'em a shake.

Here's an example of what you're looking for. This one's secured with a nut on a stud:




Here's a video of a quick and simple fix:

 

[iamdub]

-Duplicate post-