Fibreglass from Exhaust.

Not seen this before. Noticed it hanging from the tail pipe of Mrs Mull's antediluvian Punto. At first I thought maybe a prank..as we've had some idiots playing silly buggers round here lately, but on pulling it all out I surmised that it was coming from the back box/muffler..which is presumably.. like the rest of the car..on it's last legs. Amount, loosely rolled up, is about the size of a fist.

Question. Does the box need replacing urgently, or what? Mrs Mull said car drove OK last time she was out.

Obviously we will get it sorted as soon as convenient.

 

Yes that’s one of the components of the catalytic exhaust converter. Nothing really urgent, no.
It’ll get noisy and won’t pass MOT obviously.

 

Yebbut.. is it a component of the Catalytic Converter..or just of the silencer..? Converter is a whole 'nuther' and more expensive ball game.

 

It’s what the back box is stuffed with to muffle the noise. I replaced the silencer on my daughters Aygo a few weeks ago and as I took it off the tailpipe fell off and a lump of the fibreglass fell out, at first it looked for all the world like a bird and I had a confused few moments trying to work out how a thrush sized bird had got in there…

It’ll just get louder and louder, probably sooner rather than later now that it’s started to make its escape.

 

Quick Google features no mention of Fibreglass in Cat converter construction..so I'm assuming it's just the back box.

 

It will be from the back box. Afaik a catalytic converter is all metal, no fibres.

 

Can be inside any box from behind the cat to the tip. Most often in the back box others are resonators.

 

Deffo back box; the exhaust is on the way out.

 

It's the back box; cats are a ceramic substrate, and would not look like this even if it broke-up.

Resonators contain no such material either- ja ust perforated /louvred metal pipe in an empty box. Helmholtz and all that. Doelivers not just a 'silencing' task, but also - surprisingly important in achieving best engine performance (the volume, and where they are placed matters, and is not co-incinetal: acts a low-pressure termination 'open air' from the engine's pov, so makes whatever follows downstream, much less critical)

So -it's the box nearest the tailpipe; since its only a silencer/muffler - no effect on emissions, replace with cheap equiv. Actually very unlikely to be a MOT failure unless the casing has perforated letting exhaust leaking fumes before the final exit.

 

Well thanks for replies all. It's just not something I've ever seen before and I have driven a few sheds in my time.
I have a feeling that Mrs Mull's last exhaust repair was just a back box from one of the usual suspect 'multiples', so it was probably as cheaply made as poss. And of course if that exhaust 'set' is on at least the second back box, there's a fair chance it will fall apart completely under 'repair'. Whatever.. she'll get it fixed as she seems determined to drive this car until it literally falls off of its wheels..

 

Those of us who have run air-cooled VW Beetles may have come across this in the twin tailpipes. The 'tailpipe' is in fact a small exhaust damper with an inner perforated core of metal. If that rusts away the wadding (probably fibreglass) can be extracted leaving an empty tube with no ill effect to the way the car runs. Just pull the stuff out and carry on Mull.

 

If it sounds ok i'd leave it, probably only effects a marginal reduction in sound output.

I keep my back box safely hung on the garage wall alongside the cats, emissions fine so far and nothing for the local crims to cut off.

 

@dweezil - that's unusual.
D'ye mind me asking, what type of car is that ?

 

I remember stuffing the pipes of my old mans BSAs when we rebuilt em.

the inside of the tailpipe baffles are corroding and letting the ‘glass out. Hi panic, unless it gets too loud.

 

1992 Porsche 928, a bit on the cusp for emissions regs, the main problem i've had is with Lambda, cured by removing the smog pump which had to be on there for Californian compliance!

MOT requirements do change so i keep the cats in case they change the standard.

 

Off topic, but I have a friend who bought the Wheeler Dealers 928 completed restoration project. Not the best decision he ever made.. by quite some margin