Hi everybody, this is my first post on the forum and I apologize if this post isnt in the right section on the forum.

I own an 03 sedan with 149k miles and I'm experiencing an odd intermittent rattling sound coming from the engine when revved in neutral. This is not something I normally do, but recently I was showing off to my friend the exhaust sound that I love so much (I had to do it), when I noticed the rattling noise. I'm not too sure how to describe the noise other than an almost hollow sounding metal on metal rattle (if that makes any sense).

I'm not extremely knowledgeable when it comes to engines, but I do know the basics and I'm currently trying to learn as much as I can about the automotive world. Any help would be appreciated.

 

I also forgot to mention that the oil has been well maintained for the entire life of the engine.

 

I had a rattle and it was a loose cat converter.

 

More than likely heat shields on the cats. It's well known that the welds break and they rattle.

Lay on the ground next to car and have your friend rev. You'll prob hear it.

I think I have 4 hose clamps on my shields keeping my car rattle free at this point

 

Yea heat shields mine rattled only needed one clamp.sounds alot better! You can hear heat shield rattle on custom exhausts sound clips.drove me crazy the rattle!

 

Get a friend, one person rev and other person try to locate the source.

 

Its usually the catalytic converter heat shield. That's where my rattle was.

 

Thanks everyone, what would be the best way to make sure the heat shield is tight and in place? Hose clamps? Any ideas or personal experiences would be appreciated, thanks guys.

 

You can remove them, but if only one weld is broken, just get some hose clamps and tighten them around the shield.

Both sides on mine are badly broken. I have two clamps on each and it's now dead silent. Remove the clamps, and my car sounds like a kazoo.

 

I was lucky only one weld was broke one clamp no more rattle

 

https://g35driver.com/forums/6789659-post45.html

this is what fixed my rattle.