# New cat also new noise? Mystery please help **URL:** \ **Category:** Maintenance/Repairs\ **Created:** [May 25, 2019, 7:29am UTC](https://community.cartalk.com/t/new-cat-also-new-noise-mystery-please-help/140953 "2019-05-25T07:29:25Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![Hlynrobson\_150242](https://avatars.discourse-cdn.com/v4/letter/h/e19b73/32.png) [@Hlynrobson\_150242](https://community.cartalk.com/u/Hlynrobson_150242)\ **Post date:** [May 25, 2019, 7:29am UTC](https://community.cartalk.com/t/new-cat-also-new-noise-mystery-please-help/140953/1 "2019-05-25T07:29:25Z")
2005 Subaru impreza outback sport manual transmission with ~360k total but 30k on engine rebuild. So… was making gnarly cat rattles and had both catalytic converters replaced and boy did it need it but immediately after car now makes terrible rattling almost knocking noise. Sounds like engine knock almost except weirdly is way louder from inside car then from outside with hood open. Makes noise when I give it gas. While Googleing and such I’ve found videos of torque converters gone bad – well it sounds like that except I have a manual transmission. If I’ve been running on a bad cat for a while unknowingly is it possible replacing them has caused my engine to knock? More oxygen?? Helpp! Sounds like from front right wheel well area, but loudest in the driver seat. It’s an awful sounding/feeling noise but also car drives so much better now, the power increase from the terrible clogged up cat being replaced is so so noticeable. I’m both mystified and terrified cus that install wasn’t cheap and now if theres another, more serious problem I’m bout ready to roll her off a cliff… ---
**Author:** ![COROLLAGUY1](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/corollaguy1/32/7575_2.png) [@COROLLAGUY1](https://community.cartalk.com/u/COROLLAGUY1)\ **Post date:** [May 25, 2019, 9:17am UTC](https://community.cartalk.com/t/new-cat-also-new-noise-mystery-please-help/140953/2 "2019-05-25T09:17:54Z")
Can you post a sound clip? ---
**Author:** ![Purebred](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/purebred/32/46796_2.png) [@Purebred](https://community.cartalk.com/u/Purebred)\ **Post date:** [May 25, 2019, 10:43am UTC](https://community.cartalk.com/t/new-cat-also-new-noise-mystery-please-help/140953/3 "2019-05-25T10:43:05Z")
Could it be loose heat shields ? ---
**Author:** ![tcmichnorth](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tcmichnorth/32/25126_2.png) [@tcmichnorth](https://community.cartalk.com/u/tcmichnorth)\ **Post date:** [May 25, 2019, 10:49am UTC](https://community.cartalk.com/t/new-cat-also-new-noise-mystery-please-help/140953/4 "2019-05-25T10:49:36Z")
> [@Purebred](#): > > Could it be loose heat shields ? Or exhaust reinstalled too close to body, frame or any other part of car? When the engine accelerates, the motor mounts allow the engine to move, which in turn moves the exhaust. It may rub on something while accelerating. ---
**Author:** ![Cavell](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/cavell/32/43396_2.png) [@Cavell](https://community.cartalk.com/u/Cavell)\ **Post date:** [May 25, 2019, 1:57pm UTC](https://community.cartalk.com/t/new-cat-also-new-noise-mystery-please-help/140953/5 "2019-05-25T13:57:41Z")
the sound is new? were you so focused on cat rattle before that you did not hear the 2nd sound before? if not than who installed cats? the shop has no opinion on sound? ---
**Author:** ![Hlynrobson\_150242](https://avatars.discourse-cdn.com/v4/letter/h/e19b73/32.png) [@Hlynrobson\_150242](https://community.cartalk.com/u/Hlynrobson_150242)\ **Post date:** [May 25, 2019, 3:21pm UTC](https://community.cartalk.com/t/new-cat-also-new-noise-mystery-please-help/140953/6 "2019-05-25T15:21:21Z")
This sound is new. I think I used to hear a much milder version when I drove only in reverse and specifically reversed uphill. @COROLLAGUY1 here is clip. ---
**Author:** ![Hlynrobson\_150242](https://avatars.discourse-cdn.com/v4/letter/h/e19b73/32.png) [@Hlynrobson\_150242](https://community.cartalk.com/u/Hlynrobson_150242)\ **Post date:** [May 25, 2019, 3:23pm UTC](https://community.cartalk.com/t/new-cat-also-new-noise-mystery-please-help/140953/7 "2019-05-25T15:23:02Z")
Dang it couldnt get it to post. Try again after work ---
**Author:** ![Hlynrobson\_150242](https://avatars.discourse-cdn.com/v4/letter/h/e19b73/32.png) [@Hlynrobson\_150242](https://community.cartalk.com/u/Hlynrobson_150242)\ **Post date:** [May 25, 2019, 3:23pm UTC](https://community.cartalk.com/t/new-cat-also-new-noise-mystery-please-help/140953/8 "2019-05-25T15:23:40Z")
![](https://global.discourse-cdn.com/cartalk/original/3X/5/b/5bc8337b6a5e218bf2bf95370155439584e46d60.mp3) ---
**Author:** ![Scrapyard-John](https://avatars.discourse-cdn.com/v4/letter/s/f6c823/32.png) [@Scrapyard-John](https://community.cartalk.com/u/Scrapyard-John)\ **Post date:** [May 25, 2019, 3:35pm UTC](https://community.cartalk.com/t/new-cat-also-new-noise-mystery-please-help/140953/9 "2019-05-25T15:35:20Z")
Sort of sounds like an exhaust leak…maybe… Like someone mentioned above, does the shop that did the exhaust work have an opinion on the noise? ---
**Author:** ![Hlynrobson\_150242](https://avatars.discourse-cdn.com/v4/letter/h/e19b73/32.png) [@Hlynrobson\_150242](https://community.cartalk.com/u/Hlynrobson_150242)\ **Post date:** [May 25, 2019, 10:36pm UTC](https://community.cartalk.com/t/new-cat-also-new-noise-mystery-please-help/140953/10 "2019-05-25T22:36:24Z")
I’m going to take it back on Tuesday. They left for me to pick it up on Friday evening. So didnt get to chat but I had to drive it even though it felt wrong. I wanted to just leave it there.