CAR HELP please....I don't want to get taken to the cleaners

[LostHiWay]

Here's the problem. I have a 99 Jeep Wrangler..5,000 miles over warranty Whenever I accelerate I hear a rattle/vibrating noise under the car where the muffler is. I've taken it to like 4 different places and none have found anything wrong. I finally took it to the dealer and they put a new catalytic convertor on, but as soon as I pulled out of the dealership it made the same noise.

Any ideas what the problem could be?

I was thinking that it could be one of the heatshields around the muffler but I've tried bending them and nothing seems to help. I also thought that a baffle inside the muffler is loose or broken and causing the noise but the only way to be sure would be replace the muffler.

 

[Brutuskend]

Does the noise go away when the engine is warm?

If not, I doubt it's inside the muffler, though it could be.

 

[etech]

Jeeps Unlimited

If that isn't the problem you have a search of these forums may help.
Jeeps Unlimited forums

 

[LostHiWay]

No, actually it doesn't do it when I first start driving the engine or exhaust seems to have heat up before it does it. It takes about 2-3 min before I can here it.

 

[Zenmervolt]

You've already been taken to the cleaners. The catalytic converter is generally the most expensive single part of a stock exaust system. What it sounds like to me is the heat shield under the catalytic converter, had the same problem with my Accord, after 10 years the shield had worked loose, so I just pulled the shield off and the noise was gone. One thing about removing the shield completely though, you have to be careful not to park over anything flamable (a pile of leaves in Autumn for example).

ZV

 

[LostHiWay]

Actually the convertor was the only part in the Jeep that had a 5 year warranty so I didn't have to pay for it.

I was just reading in the jeepsunlimited forums that it could be a cracked Exhaust Manifold. Could this be something that could cause a noise like I'm hearing. I really don't know much about cars.

 

[bizmark]

the exhaust manifold is attached to the engine, under the hood. It wouldn't be making that noise.

edit: is it a 4x4? That may have something to do with it, esp. since you only hear this noise under acceleration. I'm not familiar with where the transfer box is on a Wrangler, but it could be far enough back that it sounds like it's coming from the muffler area.

In any case, since you only hear it while you're accelerating, I would think that it's a mechanical problem rather than simply something being loose.

 

[fastz28]

You sure it's not the muffler? The muffler on my Bronco was so rusted that it's outer shell was coming off. It was making the same kind of noise, only under acceleration. $80 and a new muffler later fixed it.