Exhaust Pipe Rusted Out Downstream of Resonator Replacement Options

[Daskuppler]

Hello Everyone,

I have a 2002 Impreza TS and found a large, nickel sized, hole right behind the resonator. Has anyone had any good success with cat back system replacements, or should I just take it to a shop to get the pipe replaced.

If I delete the resonator will it become obnoxious? I'm not looking for high performance or super loud modifications.  Louder than factory is fine, but nothing crazy

[idosubaru]

local shop here charges $50-$75 to weld a rusted flange or joint. I’ll toss them a $100, that’s too cheap. 

I’ve installed a couple of low cost eBay or rock auto exhaust parts. They bolted right up and work if that’s all you’re asking for.  They will rust a lot quicker than stock OEM if you’re in the rust belt or want them to last 10+ years. 

If you plan on owning it a long time I’d look at it carefully and if there’s any signs of other rust or rusty flanges/muffler it’s worth just replacing it all now. 

[Daskuppler]

1 hour ago, idosubaru said:

local shop here charges $50-$75 to weld a rusted flange or joint. I’ll toss them a $100, that’s too cheap. 

I’ve installed a couple of low cost eBay or rock auto exhaust parts. They bolted right up and work if that’s all you’re asking for.  They will rust a lot quicker than stock OEM if you’re in the rust belt or want them to last 10+ years. 

If you plan on owning it a long time I’d look at it carefully and if there’s any signs of other rust or rusty flanges/muffler it’s worth just replacing it all now. 

I'm in Colorado so things rust,  it not like other parts of the country. Everything else seems pretty solid, but you never really now.

[nvu]

If anything, inspect the donut flange area. if it's rusted out I'd just replace the entire thing.  A sometimes leaking and sometimes not spring loaded donut flange makes it hard to chase the inevitable p0420 code.  The muffler end can fall off and it wouldn't set codes.

No resonator wouldn't bother the neighbors, it'd bother you with highway droning if you're sensitive to that.

[el_freddo]

Removing the resonator will create a sharp crackle/raspy sound at certain revs and engine loads. 

I’d describe it as being a bit like the crackle/raspiness of a Holden 253 V8 (4.2L) with twin pipes and no equaliser pipe, but you guys wouldn’t know what I’m taking about… 

Cheers 

Bennie

[Daskuppler]

8 hours ago, nvu said:

If anything, inspect the donut flange area. if it's rusted out I'd just replace the entire thing.  A sometimes leaking and sometimes not spring loaded donut flange makes it hard to chase the inevitable p0420 code.  The muffler end can fall off and it wouldn't set codes.

No resonator wouldn't bother the neighbors, it'd bother you with highway droning if you're sensitive to that.

I do get a p0420 code periodically, it's usually on a coatsting deceleration. I replaced it s little while ago, but I'll check it. I'm definitely not a fan of the droning.

Maybe I can get a back portion from the local Subaru recycler

[brus brother]

Going on the real cheap for a nickel sized hole, there are furnace repair/sealing silicone caulks available at Home Depot good for 1000 degrees.

Cost around $15 for 10 oz caulking tube.

I have made some lasting repairs where welds at y junctions failed. Other areas have begun to leak but original repair is still solid 4 years later.

https://www.homedepot.com/p/3M-10-1-fl-oz-Red-Fire-Barrier-CP-25WB-Plus-Sealant-CP25WB-10/100166701

"3M™ Fire Barrier Sealant CP 25WB+ shall be a one component, ready-to-use, gun-grade, latex-based, intumescent firestop sealant capable of expanding a minimum of three times its dried volume when exposed to temperatures above 1000°F (538°C)."

Beyond 1000 degrees, ya got other problems.

[Daskuppler]

On 5/7/2024 at 3:03 PM, brus brother said:

Going on the real cheap for a nickel sized hole, there are furnace repair/sealing silicone caulks available at Home Depot good for 1000 degrees.

Cost around $15 for 10 oz caulking tube.

I have made some lasting repairs where welds at y junctions failed. Other areas have begun to leak but original repair is still solid 4 years later.

https://www.homedepot.com/p/3M-10-1-fl-oz-Red-Fire-Barrier-CP-25WB-Plus-Sealant-CP25WB-10/100166701

"3M™ Fire Barrier Sealant CP 25WB+ shall be a one component, ready-to-use, gun-grade, latex-based, intumescent firestop sealant capable of expanding a minimum of three times its dried volume when exposed to temperatures above 1000°F (538°C)."

Beyond 1000 degrees, ya got other problems.

Thanks for the info! I never thought about using fire caulking on an exhaust system... I've put many tubes of that stuff in buildings... Man do I hate it haha. But I bake a $15 fix!

Did you just cook the hole, or put some wire mesh over it than the caulking?

Edited May 14 by Daskuppler

[brus brother]

I just packed the hole. No mesh. My repair was in the crotch of a y as the exhaust splits to 2 mufflers. Just checked out of curiosity and it is still holding strong.
Couldn't hurt to create a "wrap" of the edges of the hole where some material is on the inside and some on the outside and then fill in the middle.

Or tuck a tiny piece of copper mesh on the inside slathered with the sealant. Attach and use a piece of dental floss or thin string to pull the patch up against the inner wall and then slather on a coat on the exterior surface.

The area I worked on wasn't conducive to cleaning so I just relied on the silicone to do its best.

Edited May 14 by brus brother