Downpipe to mid box joint weld broken

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Med_tech3
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Downpipe to mid box joint weld broken

Post by Med_tech3 »

Hi. I have a 2008 C3 1.6 auto that developed a loud exhaust noise. I investigated and found what is in the pictures. It looks like the plate attached to the downpipe has broken its weld and so the joint is no longer tight.
My question is can this be successfully and safely welded back in place?
I don't really want to have to replace the downpipe unless really really necessary.
Also if it is weldable, would a normal repair garage be able to do it?
20240101_095936.jpg
20240101_095939.jpg
20240101_095953.jpg
Thanks
Last edited by GiveMeABreak on 01 Jan 2024, 11:57, edited 2 times in total.
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GiveMeABreak
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Re: Downpipe to mid box joint weld broken

Post by GiveMeABreak »

So there is no weld between the 2 plates on this.

Citroen provide a fixing kit, which consists of the 2 spring fixings and the bolts shown below and a 'collar' that sandwiches in between the 2 plates also arrowed. So unless the actual exhaust has broken at the existing pipe welds, it may just be the sandwiching plate that has corroded and causing a loose fit.
med exhaust mod.png
I've arrowed the bits in the fixing kit and of course the collar you can't see in between the plates.
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Marc
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Re: Downpipe to mid box joint weld broken

Post by Med_tech3 »

Hi Marc. Thanks for your reply. Sorry I meant the plate on the downpipe looks like it should be further back on the pipe where the ring of metal is. I have arrowed this in the attached picture. The plate is loose on the exhaust pipe and can spin freely. I did buy a new tapered gasket for it and fitted it (you can see it in a couple of the pictures). I have tightened the bolts as much as possible but the gasket is still visible and when I start the car, loads of water drips out of the joint.
If I am wrong and that plate is supposed to spin freely on the pipe then I am stumped as to how to get the joint to seal.
20240101_095953.jpg
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GiveMeABreak
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Re: Downpipe to mid box joint weld broken

Post by GiveMeABreak »

So if the darker plate on the left in the pic above is spinning, the weld has broken and the whole cat will likely need to come off as it's a complete part, in order to re-weld it onto the pipe as far as I can see. It's obviously not right at present as it's not mating and this is just going to corrode and cause noise etc. Because these plates are both welded on to their respective pipes they are not supposed to spin. The flexible spring fixings should allow for some adjustment to help them mate correctly - BUT if the internal ring is shot, malformed / corroded, then it's not going to allow a flush fit, so looks like you need to replace the internal ring between the 2 plates and weld the left plate onto the pipe (in such a way that it will line up and mate properly).
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Marc
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Re: Downpipe to mid box joint weld broken

Post by RichardW »

Should be easy enough to weld that back on, as Marc says expect cat will need to come off. Better to try and fix the original cat, aftermarket ones are pretty ropey!
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Re: Downpipe to mid box joint weld broken

Post by Gibbo2286 »

You need this guy to do your welding. :)

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