Sounds like it mate.

Next thing will happen is you will have lack of power because it will start blocking your exhaust so the gases will stay in the engine instead of coming out of the tail pipe.

Get it changed before it does any more damage.

Gordon

 

Lat time I came across this it was nothing more than the bolts where the flexible section is needing a bit of tightening. Give that a try first.

Ken

 

Thanks for the answers so far.
I will check the 2 connecting bolts first.
Is this a common problem that the DP can actually burn the cat in the midsection??!? And if I replace the cat under warranty it will be most likely to burn this one as well, right? Anybody else who had the same experience? Do I need to take the downpipe off again?? Wouldn't really like to do this!!
Thanks for additional replies!
swiss scooby
PS: Does you mid-cat rattle when knocking on it with your hands??
PS: I am a little disappointed!!

 

No reason for change in downpipe to affect the cat. All the downpipe does is transport gas from the engine to the cat. Ø will not make a difference. A longer downpipe may let the gas cool more before reaching the cat delaying light-off but no reason to cause any damage.

Catalyst failures are either:
1) melt down, usually due to excessive fuelling ie calibration error, spark failure - OR bump starting catalyst equiped car !
2) Brick holding failure, due to failure of the mat holding the brick in place or cracks induced by other means allowing the brick to start breaking up.

A melt will not give a rattle unless it is severe enough to cause collapse of the brick, it will increse backpressure. A broken brick that is rattling will allow pieces to drop out of the front or back if you remove the section. It could be examined with a fibre optic camera if necessary.

The most common cause of rattles is loose heatshields, exhaust hanger mounting bolts and with aftermarket parts a part, particularly with flanges on, that has insufficent clearance and at a resonant frequency moves enough to hit something else.

Have a nice day - hope you get it sorted

By the way I have seen reports showing that Subaru are about the cheapest company for genuine replacement catalyst units (a little bit of +ve news )

Mick

 

Cheers Mick,
Now thats some explanation!!!
Thanks for your time writing all this! I will check all the mounting bolts first (again). I liked the idea of that camera thingy, eventhough I don't know where to borrow/check this.
Thanx again and I will have a nicer day!
swiss scooby

 

On MY00, after fitting a SS-DP + BB by keeping the original midsection (cat) in place (for less noise level), I realised a rattling noise under acceleration from the midsection. Is this normal?!? My dealer thought that maybe the midsection (cat) has been burnt by the direct heat from the downpipe!! If I knock on the midsection (cat) I hear it rattle as well. I already checked the screws on all the heatshields, they are all tight. Could it really be a burnt cat?? My dealer told me that replacing the cat would be necessary (he would even put it in guarantee!!). I am no so techy but I dont really belive that the heat could have burnt the cat! What are your opinions/thoughts?? I don't want to burn another one (the guaranteed one).
swiss scooby

 

Hmmm..., it looks like my midsection cat is definite history!! I checked all the heatshield-bolts, the two flexible screws and the screws holding the exhaust-system to the chassis. Everything is tighter than tight!! Well, I think that I need a new cat then. It looks/sounds like it is a brick holding failure. The car has only 13k km so far!!!
Actually, I still have a Magnex (resonator) center pipe that I could put on. The only thing is, if the police catch you with no cat equipped, it's a CHF 3,000.00 (GBP 1,200.00)ticket you get!!!
What would you do??
Cheers
swiss scooby

 

Check the catalyst section for external damage. If new parts have been fitted and the cat removed at the time, bad handling and impact of the part could have led to a severe enough shake to the brick to initiate a crack. If you remove the cat section and give it a good shake first one way up and then the other to see if any bits fall out. Most catalyst bricks are ceramic extrusion - small cells mostly square section. I have not checked out a Subaru catalyst to be sure about the construction. If little bits of this sort of constuction drop out the cat is definately beyond hope!
If the cat is gone I would probably replace it with a Subaru part since they are (relatively ) cheap. There are companies producing cats with lower gas flow resistance which may aid power with the turbo. - Your choice.

Mick

 

swiss scooby,
Understand your concern about the CHF 3000 ticket (!!) if you put you decatted Magnex on. But I guess you won't risk this if you take off the original midsection, remove the cat, and replace the section again. At least no visual changes to indicate there is no cat in place - better flow and no more rattle!
Have done this to my own car, front cat still in place, though. Very easy, use a large drill. Cat and holding 'mat'/tube falls out!

Simen.