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Old 06-01-2011, 06:51 AM   #1
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Exhaust leak

Probably one of the ugliest issues a car can have is when you have a small exhaust leak such that upon acceleration your car emits not much more than a dull fart.

Interestingly enough, I think that far more Porsche users have such a leak than many other car owners, and than they realize.

The reason? An interesting (read: not great) design choice on the clamp between the catalytic converter and U-bend pipe. Here in Vancouver there are quite a number of Porsche owners, and as such I see a number go by. Typically if the car is older than 5 years (both boxster and carrera, including turbo variants), I can hear the leak as they go by.

What's the fix? Not sure. I recently installed a new muffler, but in doing so, I noticed Ihad the leak as well prior to installation. So I would tighten up everything nice and tight after I put in the new muffler and alas I still had a bit of leak. The best way to test for this is to start the car cold (where you have high RPMs, thus more backpressure) and cup your hand around the 2 joints on the U-bend. If you feel any wind at all, you've got a leak. A small leak can drastically reduce the tone quality of your exhaust. Typically the exhaust will come out the ends of the clamp where it meets the pipe, not out the side.

The sleeve-type connectors are notoriously bad for sealing after any length of time due to rust deposits. I had a similar issue on my Audi of the same age where the sleeve literally disintegrated. There are infinitely better designs out there that last longer and seal better such as flanged designs.

To fix it, Sanding down both the sleeve and mating surface on the pipe may work to make a better seal. But in the end a new sleeve may be required on top of cleaning the pipe surface (about 45$ each).

If anyone else has had experience with keeping their exhaust IN the exhaust, please share.

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Old 06-01-2011, 07:07 AM   #2
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I had the same issue. Fixed it once by removing clamps and putting exhaust pipe sealent then clamping together. That lasted for a years now.

Muffler Cement 35958 Dynomax

is the one I used. But there are many types.
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Old 06-01-2011, 10:05 AM   #3
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I have the same leaks and it drives me nuts. I haven't figured out which way I want to fix it yet. I may try that exhaust cement stuff just for the hell of it.
I think a better way to pin point exhaust leaks is to go buy a $10 stethoscope from autozone and use that.

I was able to find 2 leaks at my header I was wondering if anyone has come across also. I found that I have a leak on both sides in the exact same spot. See attached photo.

The leak is where the pipe goes into the "flange." It isn't a very large leak, but it is def a leak. I just found it to be weird that both sides are leaking in about the exact same spot. Has anyone else found the same thing?
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Old 06-01-2011, 11:11 AM   #4
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Jake, your leak is an entirely different beast than the one I was describing near the muffler, but I would venture to guess that yours has been caused by a stress fracture. It looks to be in a spot that would see maximal stress from applying a load/force to your exhaust system. Do you have an aftermarket muffler? In that case the different muffler has a different hanging location and thus could have exacerbated the stress placed on your header pipes.

Also as a note, I would not bother using the cement on your header since the outer surface you are pointing to will see 600+ degrees C and no exhaust goo will withstand that, short of welding.

At the rear end, however, the exhaust goo sounds like the perfect fix and in fact I will try it out and see if it seals up nicely.
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Old 06-01-2011, 12:01 PM   #5
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I have no idea why they would leak there and yes I agree that no goo should go near there. I couldn't think of any reason there would be a leak there, but it is literally in the exact same location on each side. It's def not the main cause of my exhaust leak noise though so I am not too worried about it. I may try taking off the U pipes, cleaning them up, and re-installing them with some muffle goo. Can't hurt to try at least.
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Old 06-28-2014, 01:27 AM   #6
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I know this is an old post but I thought I would add. I have the exact same leaks. Near the u-pipes and the muffler. Im going to try the muffler cement!
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Old 06-28-2014, 08:22 AM   #7
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I think I got a similar leak on my after market exhaust. Sometimes a slight rattle on with slight acceleration and weird noise. Very brief though. I have the fabspeed spring exhaust clamp that's hand tightened. Wonder if there is a better replacement. Broke one before from over tightening so....
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Old 06-28-2014, 10:11 AM   #8
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Any reason to not weld the pipes together there at the muffler?
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Old 06-28-2014, 02:15 PM   #9
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Rp17, I would check the exhaust clamps. Turn on the car and place your hand around area of the clamps (carefully). If there's a leak you will feel air seeping through the clamp. All for four of my clamps I can feel air (all clamps were tighten again as well). I knew something wasn't right. My exhaust just doesn't feel or sound the same. I have a GHL muffler.

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Old 06-28-2014, 07:02 PM   #10
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Quote:
Originally Posted by djw8282 View Post
Rp17, I would check the exhaust clamps. Turn on the car and place your hand around area of the clamps (carefully). If there's a leak you will feel air seeping through the clamp. All for four of my clamps I can feel air (all clamps were tighten again as well). I knew something wasn't right. My exhaust just doesn't feel or sound the same. I have a GHL muffler.
Will do. I like Timco's idea as well. Everytime I take a non boxster owner for a ride and ask them if they are hearing what im hearing, I get this open mouth look after we get back. Smh... My exhaust sounds amazing so can't blame them much.

On a road trip tomorrow so hopefully when I get back, I can shoot a couple of pics of the clamp.
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Old 06-29-2014, 04:40 AM   #11
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Check out the link and scroll down to post # 14. I used these clamps on my recent exhaust install they worked great and seal very well. In hindsight I should have used these at the muffler joint also. I had a slight exhaust leak at the slip joint these clamps cured it.


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Old 06-29-2014, 12:12 PM   #12
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Thanks rfuert911sc for the reply! I saw your post through a search and I was planning on ordering these clamps!! I figure the 2" clamp would work fine connecting the cats to the u-pipes but what about the muffler? What is the size of the stock clamp which connects the muffler to the u-pipe? 2"? Do you think this style of clamp would work to connect the muffler? Thanks!
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Old 06-29-2014, 04:09 PM   #13
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Originally Posted by djw8282 View Post
Thanks rfuert911sc for the reply! I saw your post through a search and I was planning on ordering these clamps!! I figure the 2" clamp would work fine connecting the cats to the u-pipes but what about the muffler? What is the size of the stock clamp which connects the muffler to the u-pipe? 2"? Do you think this style of clamp would work to connect the muffler? Thanks!
I don't know if the 2 " will fit but a caliper is your friend .......just measure it.
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Old 06-29-2014, 04:50 PM   #14
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Ok thanks!
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Old 07-03-2014, 01:14 PM   #15
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Quote:
Originally Posted by rfuerst911sc View Post
Check out the link and scroll down to post # 14. I used these clamps on my recent exhaust install they worked great and seal very well. In hindsight I should have used these at the muffler joint also. I had a slight exhaust leak at the slip joint these clamps cured it.


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Those clamps are very good. Few other forum members are using them that solved there problems.

Her is a few pics of my clamp that I think is causing me problems. Slight leak i'm thinking. Those clamps mentioned earlier wont work ends of these pipes.




Second clamp is one I got from Summit Racing. Any alternatives to these?
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Old 07-03-2014, 02:01 PM   #16
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Any reason to not weld the pipes together there at the muffler?
Future disassembly. The stock clamps are a wear item. New oem clamps help alot.
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Old 07-03-2014, 04:33 PM   #17
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Rp17..If your talking about the clamps that connect the muffler to the u-pipes. These clamps are similar to the OEM clamps but they offer a stainless steel (last longer) version. The stock clamps are aluminized steel. Along with a little muffler cement, it might cure the leak.

AccuSeal Exhaust Clamps: Torca AccuSeal Clamps in Stainless Steel or Aluminized Steel for Lap Joint Connections

Last edited by djw8282; 07-03-2014 at 04:40 PM.
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Old 07-03-2014, 07:14 PM   #18
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Rp17..If your talking about the clamps that connect the muffler to the u-pipes. These clamps are similar to the OEM clamps but they offer a stainless steel (last longer) version. The stock clamps are aluminized steel. Along with a little muffler cement, it might cure the leak.

AccuSeal Exhaust Clamps: Torca AccuSeal Clamps in Stainless Steel or Aluminized Steel for Lap Joint Connections
Thanks for the reply. Took a look at those clamps from the link and they are flat. The connection from the mid pipes to the muffler are raised and rounded. The pics above has a groove in then for it to seat well I guess. I will give thise guys a call on Saturday see what they say. Happy 4th guys.

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