Loud Exhaust after Transmission Replacement

I had the transmission replaced on my 2015 Impreza Hatchback with 82k miles and now the exhaust is substantially louder than it was before the repair. Lots of drone and burble. To quote my wife, “it sounds like a boat.” I inspected the underside of the car and didn’t find any loose connections or leaks in the exhaust. The sound is coming directly from the tail pipe almost like I had a louder exhaust installed.

Could the loud exhaust be the result of the transmission replacement or is it a complete coincidence? Do I need to replace it?

 

Unrelated unless they broke, removed or replaced something.

Are all the heat shields still there post transmission fix?

 

Have you been under the car while running and under load to see/hear where the leak may be coming from?

 

As far as I can tell. It’s not really a rattle , it sounds more like the muffler has gone bad.

 

I was under it yesterday while my wife ran up and down the rpms. Couldn’t find any leaks nor any loose fittings. After listening under the car I can confirm that it actually sounds louder while in the car. Definitely coming from the trunk area.

 

Do you have any videos and pictures? Have you pulled out the exhaust to see if there's any holes on the top part of the exhaust that can't be seen just from looking underneath? Does it seem like the exhaust has been tempered with?

 

I don’t have video but I’ll capture some and post later this afternoon.

I have not pulled the exhaust to check for holes but that’s a good idea and I’ll try to do that in the coming days. From what I can tell the exhaust does not appear to be tempered with. Bolts are still rusted over and I don’t see any sure signs of it being moved.

 

Did the shop cop your cats lol?

 

The exhaust does have to be removed/disassembled to replace the transmission, so it's completely possible that something was effected. Leaking gasket or rattling heat shield the far more common causes (as already mentioned). But other changes are possible, or it might be a coincidence.

Where was it done? IIRC those CVTs (assuming it is not a manual) had an warranty extension, so I ASSume it was done at a dealership....but I could be wrong.

 

Is a window down?

 

i've seen multiple times where the flanges get rusty and will leak out through there. The top of the flange where your midpipe meets the muffler either has no gasket, or some of the flange has been eaten away and exhaust is leaking up towards the cabin.

 

Yea, when I replaced my exhaust a while back the Minnesota Road salt had permanently fused it together. Definitely possible that removing and installing it was enough to open a hole up. Same thing with the muffler.

I used to have a Jeep Grand Cherokee with an exhaust leak and muffler rusted out, and it sounded full boat motor like yours so still where my money is at.

Assuming it was a reputable shop/dealer, someone stealing your cats would seem unlikely but at today's prices who knows and worth a flashlight check if you take it off.