niner niner seven

Team, my left exhaust tip seems to rattle and cause some noise per the video enclosed. The sound is def. coming from that particular exhaust.

I have searched the forum for likely causes but nothing bore fruit.



https://www.youtube.com/watch?v=5gzC...ature=youtu.be

When I gently place my foot on the tip it seems to quiet it down some. 2006 4S 92,000 miles. I noticed the sound 2 -3 hours into a drive at city and highway speeds in 90 degree heat as an FYI.

Please find enclosed photos of the underneath as well for your inspection/review. After waiting for the exhaust to cool with my hand I tried to move the exhaust but it was as tight as the right non-noisy exhaust tip.

What do you suspect is the culprit?

Thank you in advance.

WindyCityC2S

I have had my "straps" "break" in 2 places. One place is where the "top" strap connects to the top of the pipe (about 2 o'clock in the last picture--under the connection of the manifold to the cat). The other place was where the bottom strap connects to the pipe on the right (in the bottom pic--near where there is some reddish color as the strap bends upwards). I had mine welded off the car. I was quoted $200 from a muffler shop (with the muffler off the car!!!). A friend did it in 2 minutes with a welder.

Gonzo911

+1. Common problem and an easy fix.

AWay

Agreed, super easy fix if you're handy with removing the mufflers from the car.

Took mine to Monroe muffler and the gentleman welded them on the spot for a $20. He said the weld should actually be stronger than the strap was originally.

niner niner seven

Thank you for replies thus far.

I wanted to update this post and welcome any additional comments you may have.

This past weekend I was able to get other sets of eyes from 911 DIYers. We have narrowed it down to the passenger, right side down pipe header.
Please see the video enclosed for the noise analysis.

https://www.youtube.com/watch?v=HTYH...ature=youtu.be

The piece that is being pointed to needs to be tightened.

A side note: when I turn on the AC the exhaust rattle starts, when I turn off the AC the rattle goes away.

Also, I did the 60k mile service myself (92k on the car now) I imagined I had to remove that piece to get to the plugs but in honesty do not remember. It didn't rattle after the 60k was performed but is now acting up 30k later?

Again comments welcome on the all the above thank you.

niner niner seven

Updating this post. I found that the clips that hold the PSE vacuum hose in place had rusted and were dangling onto the exhaust pipe system likely causing my exhaust tip to rattle.

I replaced the two lower clips that had both rusted on each side. (there are actually four clips in total but the higher two clips did not need replaced and were still intact).

Petza914

Wow, nice analysis and find on the clips vibrating and causing the sound.

1. If for some reason that doesn't resolve the rattle issue, there are a couple other things I'd check.
2. It could be noise stemming from broken-down coils in the catalytic converter, and that noise emanates through the exhaust system to sound like it's coming from that one side from the tip. Putting your toe on the tip might stop the noise simply by limiting the movement of the exhaust system while the car is running, just enough to stop the rattle inside the cats, so you think you've stopped movement at the tip, but you've actually stopped it much further upstream at the cats. Tapping directly on the cats with a rubber mallet should allow you to hear if there's any rattling going on inside of them without having to disassemble anything.
3. Also, at the joint you point to in your picture, since that was apart once, did you use a new gasket when you reassembled the joint, reuse the old one, or not use one at all? If anything other than a new one, there could be an improperly sealed joint there, but it's unlikely that would sound like a rattle, more like an exhaust leak and after some miles you'd see evidence where carbon from the exhaust was exiting through the joint.

I I find that Fabspeed has some of the best exhaust gaskets out there and you can get a complete set of 4 (headers & cats) for about $75. These are much better than the paper thin metal OEM gaskets and better than other asbestos-like material I've also seen used. An automotive stethoscope can also be very handy for pinpointing where all types of noises are coming from. These are pretty much a doctor's stethoscope, but with a metal rod on the end you can touch to different parts of the car to really be able to listed to what's going on in there.

Let us know what the fix turned out to be.

niner niner seven

Thanks for the reply.

The clips did not stop the rattle. I was able to repeat the sound. Here is a video of the exhaust system being tapped with the rubber mallet as you directed. I am holding the camera while my father taps for the noise. Please let me know what you think.


I went out and purchased an engine stethoscope I will let you know what I hear.

Petza914

Can you change the Privacy setting on the video from Private to Public or whatever the one between is a here people with the link can see it?

niner niner seven

Yes sorry please see if this works

niner niner seven

This video clip is of the engine in neutral with the AC on and the rattling (again this rattle only occurs on the drivers side exhaust):






When the AC is disengaged and the engine is in neutral, the exhaust tip has little to no rattle and goes back to normal idling:

niner niner seven

I will add that I did try to tighten the bolt holding that tip in place. There was not much to tighten it was tight as he11.

Petza914

The AC comment is interesting. It's possible that either the additional load of the AC compressor running makes the exhaust shake more to where you can hear the rattle or that it could be something related to the pulley that is part of the AC Compressor and it only makes noise when the compressor clutch is engaged, not when the compressor clutch isn't engaged and just the idler pulley is running.

It would be interesting to loosen the one bolt for that exhaust tip and completely remove it, which will tell us it's actually in the tip itself or somewhere else. If somewhere else, we'll have to keep looking.

I think putting the tip of the Stethescope on different parts of the exhaust may help to pinpoint the source of the sound. Unfortunately, if none of those ideas work, you may have to take the exhaust apart and shake each piece individually to see which one has loose baffles or broken-up catalytic converter material in it.

Gonzo911

Rattles suck. They never come from where you THINK you hear them. My 996 had an annoying rattle in the cabin and I knew...just knew...it was coming from the dash. Had my wife press on every inch of it while I drove. Nothing stopped it. From her seat she knew...just KNEW... it was coming from the passenger door panel. Another drive. Also nothing.

Lived with it for weeks. Would pull over and double check the dash, both door panels, headliner. Again....nothing.

Turns out it was the ashtray.

This post doesn't help you one bit...but I am going to say a prayer for you because rattles suck.

niner niner seven

Pete and all thanks for your help. I took the exhaust tip off drove around, no sound w AC etc at idle. Glad I was able to determine the issue with your help. Also this thread in 996 forum was helpful. Reinstalled my exhaust tip we will see.....

https://rennlist.com/forums/996-foru...tml?styleid=13

In mean time if it acts up again I think I should replace the nut bold set-up in the photos below? Problem is that set-up is welded on. idk, thoughts welcome.