# Permeability of a good flex pipe **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** lesabre, buick\ **Created:** [August 11, 2022, 8:37pm UTC](https://community.cartalk.com/t/permeability-of-a-good-flex-pipe/185748 "2022-08-11T20:37:17Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![jeff\_177189](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/jeff_177189/32/26083_2.png) [@jeff\_177189](https://community.cartalk.com/u/jeff_177189)\ **Post date:** [August 11, 2022, 8:37pm UTC](https://community.cartalk.com/t/permeability-of-a-good-flex-pipe/185748/1 "2022-08-11T20:37:17Z")
I just got a replacement flex pipe (a cat thief cut the most expensive pipe in the vehicle) and before installing, on a whim I capped one end with my hand and applied a few psi of lung air to the other and found that surprisingly it leaked. I’ve never tested this before - I assume it’s supposed to not leak at all and I got a bad part, right? ---
**Author:** ![weekend-warrior](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/weekend-warrior/32/26122_2.png) [@weekend-warrior](https://community.cartalk.com/u/weekend-warrior)\ **Post date:** [August 11, 2022, 8:40pm UTC](https://community.cartalk.com/t/permeability-of-a-good-flex-pipe/185748/2 "2022-08-11T20:40:45Z")
If it is leaking out the side of the pipe, then it is defective. what good is a pipe if you are going to have an exhaust leak. ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [August 11, 2022, 8:41pm UTC](https://community.cartalk.com/t/permeability-of-a-good-flex-pipe/185748/3 "2022-08-11T20:41:24Z")
Yeah. If it leaks, you could get a the dreaded P0420 code. Tester ---
**Author:** ![pleasedodgevan2](https://avatars.discourse-cdn.com/v4/letter/p/ad7895/32.png) [@pleasedodgevan2](https://community.cartalk.com/u/pleasedodgevan2)\ **Post date:** [August 11, 2022, 10:08pm UTC](https://community.cartalk.com/t/permeability-of-a-good-flex-pipe/185748/4 "2022-08-11T22:08:25Z")
I think they all do that before they’re hot. Seriously, look how it’s made. That’s the reason you tested it. ---
**Author:** ![jeff\_177189](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/jeff_177189/32/26083_2.png) [@jeff\_177189](https://community.cartalk.com/u/jeff_177189)\ **Post date:** [August 11, 2022, 10:54pm UTC](https://community.cartalk.com/t/permeability-of-a-good-flex-pipe/185748/5 "2022-08-11T22:54:00Z")
Well to be honest I’ve had bad luck with flex pipes in the past, so I thought I’d test it _before_ it went on the car this time. This unit doesn’t have that universal mesh thingy visible from the outside - there’s a collar and if you peer into the void it appears there’s a stainless spring going around everything - you really can’t see what’s going on in there. It’s not a cheap piece of pipe unfortunately and I really don’t want to do this twice. ![51jUsxS5uUS.AC_SL1500](https://global.discourse-cdn.com/cartalk/original/3X/b/6/b6ddcde493da99a723bc691cf2b059533e9e22a1.jpeg) ---
**Author:** ![pleasedodgevan2](https://avatars.discourse-cdn.com/v4/letter/p/ad7895/32.png) [@pleasedodgevan2](https://community.cartalk.com/u/pleasedodgevan2)\ **Post date:** [August 12, 2022, 4:37am UTC](https://community.cartalk.com/t/permeability-of-a-good-flex-pipe/185748/6 "2022-08-12T04:37:25Z")
Well that’s not the type of flex pipe I thought it would be. Now I wonder if they still make the braided ones. Even so; it may still leak before installation. I hope that’s the case. ---
**Author:** ![FRANKM](https://avatars.discourse-cdn.com/v4/letter/f/2bfe46/32.png) [@FRANKM](https://community.cartalk.com/u/FRANKM)\ **Post date:** [August 12, 2022, 12:35pm UTC](https://community.cartalk.com/t/permeability-of-a-good-flex-pipe/185748/7 "2022-08-12T12:35:15Z")
Or worse-- The dreaded DOA toe tag.