Hi everyone, I drive an '06 with 17,000 miles on it. The car's great, but I just noticed this rattle and I hope to learn more about what it might be before going to the dealer.

It sounds like a sheet metal part under the car. Location seems to be underneath the front seats or maybe a bit forward, but more towards the center, near the transmission tunnel perhaps.

It only happens at freeway speeds, and the rattle sometimes seems to correlate with that very subtle wind buffet noise that's audible above 60mph. But it's not near the windshield or in that area, at all.

Different road surfaces don't seem to make much difference, whether it's fresh asphalt or superslab type concrete.

It's gotten worse fairly quickly. I was on a freeway trip yesterday and first noticed it happening occasionally (I thought it was the metal handle of my bag vibrating, that's kind of how it sounds), but by the time I was returning home, it was constant.

Like, t-t-t-t-ting-t-t-t-t-t-t-ting-t-t-ting-ting, a very 'quick' noise, not like a creak or thunk.

It seems to get a bit worse when, at freeway speeds, I floor the accelerator.

Does that sound like a loose heat shield on the exhaust system somewhere? I did notice that the plastic panel under the very front of the car seemed loose, but I tightened it and the noise didn't go away. It sounds like metal, anyway.

Beyond that, I don't know what to do. It's really annoying, and loud enough to where I can't ignore it!

I hope someone can help. I've searched the site a bit, but am not coming up with anything yet.

Thank you,
~Natalie

 

The first thing that I'd do is to try to check under the car, however, unless you are the size of a gerbel, you'll need to either jack it or roll it up on some ramps. You've already started along the right direction already, checking for loose pieces. Crawl (or roll with a creeper) under there and look for loose or broken pieces. Guessing will only get you so far, you will still have to find and prove what the issue is, unless you pay (or talk into) someone else to do it for you.

 

YEs try the easiest first. You need to lift up the car and check everything there, exhaust brakets, heat shields, there are many htings that can be loose down there.

Ill tell u a story lol...when I had my GS400 I heard a rattle, it would only happen sometimes and I couldnt tell exactly where it was coming from, it sounded like it could be anywhere...to make long story short I disassembled my complete interior looking for this, and after many months of frustration I decided to put the car on a lift and closely inspect under the car. Turns out it was an exhaust bracket which was just a little loose. I wish I would of done that in the first place instead of taking my car appart like an idiot.

Good luck!

 

Thank you. I jacked up the car and looked underneath.

The sheetmetal pieces that are clamped to the exhaust pipes seem tight, I don't think that's the issue.

There seem to be two heat shields, one on the passenger side and one on the driver's side, about 18" long, running lengthwise along the sides of the tunnel area near the transmission pan (I think that's what it's called), those seem tight too.

But...there's also another one that is bolted to the chassis on each side of the transmission tunnel, forward of those other two, it's 'u' shaped and runs from side to side, following the shape of the tunnel above the exhaust pipes, just behind the engine compartment/cowl area. I think that's where the problem is...or should I say, was!

First thing I noticed is that this 'u' shaped piece was a bit loose, so I tightened as many bolts as I could.

The second thing I noticed is that on the driver's side there's a bit of space between the chassis and heat shield, but on the passenger side it was hard against the chassis towards the rear (even though the attachment methods, spacers, etc. are exactly the same on both sides). I went to increase the space between the shield and the chassis by bending the edge just a little bit, so it'd be like the driver's side, and when I did all this junk fell out, including a few small rocks!

So I took it for a drive on the freeway, and the noise seems to have gone away!
:-)

The one thing that still concerns me is that, if I rap on that u-shaped heat shield with my knuckle, it makes this dull resonant sound, and I'm worried that I shouldn't have bent it like I did.

Before I bent the edge, it made a higher pitched sound when I rapped on it with my knuckle. Now that there's an airspace on both sides, the sound is lower pitched and I can feel it vibrating for a second or two. I drove the car and it doesn't seem to resonate over the different road surfaces I encountered, though.

My question is, now...are these heat shields intentionally tight against the chassis on the right side to limit the resonance, or was that just a manufacturing tolerance that ended up to where it didn't fit exactly evenly on both sides? Should I be worried?

I know, I worry too much, but I really like this car and I'm clearly not an experienced mechanic.

I can't believe I actually seem to have figured it out!

 

Natalie-nice job! I love the posts when you present a problem AND fix it yourself!

Your car is under warranty still, isn't it? If this didn't fix it, I wouldn't mess with it anymore and just bring it in. One thing you don't want to do is start stripping bolts or bending stuff and void any warranty.

On my 2002 I had some flanges replaced due to rattling when I accelerated above 3k RPM's. I could hear it when it was parked though, not on the highway.

Let us know if this did the trick.

 

It sounds to me like you did figure it out and fixed it. There shouldn't be anything that is loose on the underside of the chassis. Also, without knowing what you bent and how you bent, it is hard to say for sure whether that is a problem, but it sounds like it will be just fine. If it is underneath the car and pliable, then the likelihood of bending it causing a problem would be low since that is the most vulnerable portion of the car and the engineers should have expected it to get banged up from normal driving. If it isn't making noise and still allows airflow, then it is likely to be okay.

I'd just say, great job Natalie.

 

If its not making any noise ur fine, those heat shields dont have to be perfectly aligned or anything, so dont worry about that unless you have a noise problem.

 

Thanks everyone, I appreciate your input.