RAudi Driver

That's some informative information. I think for this of us who don't weld, we could just drill a hole in that area and throw a few rivets in to it.


Thanks for the open heart surgery.

twodollardoug

Great work. You fixed it at home, and on your time table. And you didn't have to buy a new exhaust. Good job. You're repair is probably good for the life of the car.

twodollardoug

This should DEFINITELY be archived in the DIY section.

skinnytirez

Personally I wouldn't drill and rivet it as I don't see that lasting; with the vibration, and the heat cycling It would likely break again... could always try and then weld if that doesn't pan out.

Thanks for the kind words- fingers crossed it lasts forever.

Hopefully this will help someone else out in the future; I looked everywhere for pics showing the internals of the system before hand. Hopefully if anyone else attempts this they read the last line of my post before cutting the whole thing apart lol

darrenbt

I'll update this thread for future searchers.

My 2012 CTT started demonstrating the same rattling exhaust sound at around 130,000km. I popped off the muffler and used a rubber hammer handle to narrow down which of the baffles was loose and on which side. In my case it appeared only one baffle was loose on top side only. I drilled several holes through the outer muffler skin to expose the loose baffle and had a shop spot weld in each of my drill holes. Worked like a charm and solved the rattling problem for $50.

I drove it around for a day without the muffler attached. Obnoxiously loud and very entertaining for about two errands.

twodollardoug

I also wanted to thank you for posting your pictures. I used your pics to open up my exhaust and pull all the stuffing out. Worked like a charm.

darrenbt

Twodollardoug how was the result removing the exhaust packing? My 2nd cat bypass pipes have caused a drone that only occurs at idle when in gear while stopped at a light. I love the slight extra sound when driving around, especially on startup and shifts. I'm tempted to remove them and modify the muffler to keep the same sound level.

twodollardoug

It made some difference but not as much as I was expecting. I was worried that it would be too loud, but as you can see there isn't a lot of packing in there to begin with. With my secondary cats removed along with the stuffing I think it's perfect. Nice deap tone but not obnoxious. It is still a luxury SUV with a little rumble. If I had to pay someone to do it for me I don't think it would be worth (price depending I guess) but for 3 hours of my time I'm happy.

geetee

I'm doing something similar but removed all the packing from the very outside chambers. The whole outside chamber is filled with packing. We'll see if it makes a difference in sound

twodollardoug

Do you have any pictures of the locations of the packing?

twodollardoug

I just saw the packing on the outside. I missed that when I took mine apart. Please post up the difference.
I may redo mine if you are successful.

geetee

The area that you cutout has that outer mesh. The very outside chambers are packed with wool/fiber with no outer mesh housing. So, if you remove all the packing, you can see the exhaust pipes directly. The pipe that passes the outer chamber portion is perforated in multiple spots. You can weld some of the perforated areas shut to increase exhaust flow directly out the exhaust pipe. That would increase noise also.

twodollardoug

Right... If you remove ALL of the stuffing, you essentially turn the muffler into a flow master in the stock shell.

991TurboTim

The same thing happened on mine. My secondary cats were removed that will cause the muffler to fail and eventually found someone to do the same on mine. I will call this a "rebuild" where every braket and internal component was re-welded. According to the fellow that did the rebuild "it won't happen again". Please see below for details on my experience:

- The process to get it repaired was painful and could have been much more costly (like $3,500 versus the $2K I spent)
- I tried ordering a new one from 3 Porsche dealers. "No Go"...
- Details on $3,500. The cost of a new muffler was $2,500 with shipping plus labor costs (est $500) and add to it I have CTTS muffler tips and inlet pipes would have needed to be retrofitted on the 958 muffler would have brought the costs up another $500 (minimum). So, to do a new one would have been $3,500 for me all in.
- I looked at doing a used one and they ranged from $500 to $1,000 + shipping for the muffler alone then again, add labor. Regardless if brand new or used I didn't trust the longevity of the muffler (no cats).
- Another topic: if you have a 958.1 and are looking to swap out the current muffler tailpipes on your vehicle to "Turbo S" dual square shape". On the 958 there are 2 inlet pipes that go into the muffler. The 958.2 have a 1 inlet pipe from the exhaust tips into the muffler. Takes skill do do this work and ensure the tailpiples line up "right".