Old Volvo GL 440 and this is coming out of the exhaust pipe. No noise, all working fine but this cosmetic thing: does it mean that the exhaust gases are now not well filtered out? Does this mean that the catalysator need to be replaced or something else?

Looks like Fiber-glass coming from resonator

enter image description here

Looks like stuff coming from muffler

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Looks like part of the muffler to me. You should have it replaced it could end up obstructing the exhaust.

  • So this is the thing that blocks the sound, softening it by removing certain high frequencies. Is this a large project and does it require changing the whole catalysator or just some part of it? Any cost estimate? Possible to do myself (not being a mechanic)? Is it possible to open the catalysator and replace the muffler stuff with new stuff? – hhh Dec 15 '13 at 23:10
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    @hhh, if this is some of the sound deadening material from inside the muffler then, no, this isn't a big job nor does it affect emissions. A muffler replacement would solve the problem. In fact, when removing the muffler, you'll be able to see exactly where those filaments are coming from. – Bob Cross Dec 15 '13 at 23:14
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    @hhh the muffler is different than the catalysator, the muffler will be furthest away from the engine. It is something you should be able to do as long as it's not severely rusted. They can sometimes be a PITA though. – Move More Comments Link To Top Dec 16 '13 at 0:46
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    I got it fixed and the car energy efficiency improved from 12-15 liters/100km to about 6-8 liters/100km, remarkable cost saving! Wow! – hhh Oct 27 '14 at 0:53

I found pretty good video about changing the muffler here. As Larry said, it is not the catalysator but the part before the catalysator. It looks like something that even an amateur is able to do. In Finland, the cost is about 60EUR for the part so not expensive part.

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(source of the image)


  1. muffler = äänenvaimentimet, takapönttö (Finnish) = Ljuddämpare (Swedish)
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    Just to clarify your answer, are those filaments in the original picture coming out of the tail pipe (as labeled in the diagram)? If so, you're likely looking at material from the resonator. If you remove the resonator and the filaments are still coming out of the connecting pipe, you're probably looking at material from the resonance chambers in the muffler. – Bob Cross Dec 16 '13 at 18:44
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    @BobCross yes the filaments are coming from the tail pipe. So true: it is possible that they are from resonator or muffler. So it looks that the best option is to replace muffler, resonator and tailpipe at least? I am not sure yet whether the best idea is actually replace all components, also the catalytic converter so all components would be about the same condition and age. I think it would a good idea or is it a waste to buy a new catalytic converter as well? – hhh Dec 17 '13 at 14:33
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    The reality is that it's a lot easier to replace the exhaust components one at a time. Each chunk is going to be somewhat hefty, rusted and annoying. You really don't want the whole set of components dropping on you at once. My suspicion is that you've blown some material out of the resonator. Its geometry implies a fiberglass collar around a straight air path. By the way, if you'd like a bit more back and forth discussion than will fit in the comments, please join us on the chat. – Bob Cross Dec 17 '13 at 16:55

The tailpipe and silencer assembly is what you have pictured. The tailpipe and silencer is at the end of your exhaust system. Because of its position in the system it gets hotter and colder more often, and corrodes more quickly then any other part of the exhaust. Exhausts tend to rust from the inside to the outside first. This is what has happened, and it has released the fibre-glass sound absorbtion material from inside the assembly.

You need to replaced the tailpipe and silencer, labelled resonator in your picture. Not changing the resonator will allow the fibre-glass to shift and block the exhaust. A blocked exhaust will prevent the engine from starting if the blockage becomes great enough.

  • 'Tailpipe and silencer' would be called 'muffler' in Gods Own Country. – Allan Osborne Dec 16 '13 at 16:32
  • +1 Is it a good idea to the change the resonator at the same time as the muffler? If the muffler is corroded, the resonator must also be corroded -- this is how I understand it. Or does it matter whether the resonator is corroded? – hhh Dec 16 '13 at 17:18
  • It is the resonator letting go in your photo. When coming to replace the resonator an assesment of the complete system would be a good idea. – Allan Osborne Dec 16 '13 at 21:44
  • You mean that a good idea would also be to change the catalysator, the resonator and the muffler at the same time? I understand you so that the best idea is to change at least the muffler and the resonator because they are farthest away from the motor, right? I don't know about the cost: muffler 60EUR, resonator also something like that and the catalysator?! – hhh Dec 17 '13 at 14:21
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    Your photo shows the resonator with its fibre glass coming out of it. This should be replaced. Any other replacement of parts is subject to further examination of the system. – Allan Osborne Dec 17 '13 at 16:12

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