Exhaust leak

[mikstew]

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.