2001 V70 2.4T New loud exhaust sound from front of car

Post by **prwood** » 03 Jun 2021, 13:47

I hit a particularly bumpy patch of road today, and immediately after going over it, I'm hearing a new, loud sound coming from the front end of the car. It sounds like a hole in the exhaust prior to the muffler, so I'm wondering if a connection between exhaust components came loose, or something got banged and developed/exacerbated a hole or dislodged some corroded material that had built up. The sound gets worse/louder when I hit the gas. I took a quick look underneath and didn't see any parts missing or anything hanging off, so I suspect it's a hole somewhere that's covered up or harder to see. Hopefully I'll have a chance in the next few days to get under there and take a proper look. The exhaust system is one of the pieces I have the least experience with.

Any guesses as to what the culprit might be or suggestions on where to look?

cleven · Post by **cleven** » 03 Jun 2021, 14:19

Could be where the resonator and cat bolt together. That’s covered by a lower braces I think.

Post by **jonesg** » 03 Jun 2021, 15:10

The flex pipe, that braided stainless coupler , is a weak link.
Car has to be running to find it and access is from below, so a couple of jackstands.
Might want to check for missing rubber hangers if a jolt did the damage.

Post by **prwood** » 04 Jun 2021, 11:52

I was able to get under the car and take a proper look today. Turns out the problem is further back than it seemed. The pipe at the back of the catalytic converter is cracked. The location of the crack is indicated by the arrow in the attached diagram:

: 0900c8af878ed6c6_2126_3106_1.jpg (45.77 KiB) Viewed 1709 times

Here are a couple photos:

Considering the age of the car, and the expense of a new catalytic converter, and the fact that I don't have any welding skills, I'm wondering if I could get by with a product like "Holt's Gun Gum"?

This seems to be a UK-based product, but I'm assuming something similar is sold in the US?

motormikeyman · Post by **motormikeyman** » 04 Jun 2021, 13:50

The same thing happened to my 99 XC70 when I went through a big puddle. Had pretty good success with a Torca clamp and high temp silicone.

https://enginepartssuperstore.com/Categ ... Stainless/

Post by **prwood** » 04 Jun 2021, 19:34

motormikeyman wrote: ↑04 Jun 2021, 13:50 The same thing happened to my 99 XC70 when I went through a big puddle. Had pretty good success with a Torca clamp and high temp silicone.

https://enginepartssuperstore.com/Categ ... Stainless/

Interesting. How/where do you apply the silicone?

I found a exhaust/undercar shop that gets good ratings from the locals and was thinking of taking it there just to get an estimate on repairing the crack, given that I don't want to replace the cat. If it's reasonable I may go that route, if it's too much then I'll DIY. Just trying to gather info on my options.

Post by **kcodyjr** » 04 Jun 2021, 20:25

That's too close to the cat and the metal is pretty rusty, otherwise you could try clamping a soup can over the breach. In this case, I don't think so. Also, that sure looks like a hole punched in the cat itself.

My advice is to go to the nearest junkyard and look for an intact downpipe assembly.

Technically, you're supposed to have used cats tested for catalytic functionality, but nobody's going to enforce that.

Post by **prwood** » 05 Jun 2021, 06:36

kcodyjr wrote: ↑04 Jun 2021, 20:25 That's too close to the cat and the metal is pretty rusty, otherwise you could try clamping a soup can over the breach. In this case, I don't think so. Also, that sure looks like a hole punched in the cat itself.

My advice is to go to the nearest junkyard and look for an intact downpipe assembly.

Technically, you're supposed to have used cats tested for catalytic functionality, but nobody's going to enforce that.

So if I understand correctly, you don't think there's any way it can be repaired, and my best bet would be to replace it with a junkyard pull? I don't see any holes in the cat itself, not sure if you're seeing something in the photo other than the break just after the cat, but I didn't hear or feel any exhaust coming from anywhere else.

I'm trying to figure out which models would be compatible with my car. Based on FCP's site, it looks like the model used in my car was only used in year 2001 turbo non-AWD V70/S60s: https://www.fcpeuro.com/products/volvo- ... 39#fitment -- so my options for donor vehicles would be pretty limited.

EngineeringBloke · Post by **EngineeringBloke** » 07 Jun 2021, 14:48

I don't see any holes in the cat itself

I see the crack behind the cat but there appears to be a dent with cracks an inch or two in front of that in the cat itself. Is the cat damaged?

Given the size of the crack, I wonder if the lower back pressure would reduce any fume escape from tight cracks in the cat, but the cat looks bad to me.

I'd get an opinion from a muffler shop, even tho they may be motivated to recommend replacement. I have had good luck with S60 muffler repairs from a NE chain that does Custom Exhausts.

Post by **prwood** » 07 Jun 2021, 18:41

Are you talking about this spot here? I noticed that. It looks like material that was part of a repair of some sort, but I haven't had anything done here since I've had the car (since 2015).

I'm taking it to a reputable muffler place tomorrow for an opinion on repair.