Hi,

Anyone have experience repairing or replacing the downpipe / catalytic convertor?

Our downpipe (on a 1998 1.9D) has cracked just after the cat - looks weldable but I assume replacement is better - expensive though ..... I checked around and the best I can do is online

Get it welded up if you can find someone to do it

looked at doing same to my pickup,quoted by local exhaust manufacturing centre

No actual problem with welding near a cat as long as the part has cracked rather than disintegrated due to rusting.

As Herbie says though, a cat replacement pipe is just a matter of being able to get the right bore pipe or a bore stretcher.

Mine split on the flexi part

They are expensive , I found Butts to be the cheapest , but still expensive

You could try a bespoke exhaust company to see if they can help

Pipewerx may possibly help 01704 897778

Sarah

Get rid of it!

You don't need it.

You can get custom pipes made and/or get the crack welded for about

Thanks for the advice... . I favour chopping the cat and rplacing with a straight through section, but reckon welding could be an option - either way it means pulling the pipe! My neighbour recommended brazing as an option as this is more flexible, but we shall see what happens. I needed the car this weekend so ended up doing a hideous 'gun gum' wrap repair reinforced with additional clamps and strips of metal :( . Hope it holds on the 100 mile round trip!!! Next week the proper fix.....

Mine has had a patch weled to it,done by previous owner at sone time.Fairly sure Butts price is

Never done it as close to a box as you described, but I've done an exhaust bandage, bean tin (literally) and Jubilee clip repair a couple of times. I got the idea from my Dad, who once got 3 years (Morris Minor MM, but even so) out of one of those jobs.

Never done it as close to a box as you described, but I've done an exhaust bandage, bean tin (literally) and Jubilee clip repair a couple of times. I got the idea from my Dad, who once got 3 years (Morris Minor MM, but even so) out of one of those jobs.

They last about a week. On a modern exaust I doubt they would last a day as the higher flow and pressure would be problem. If the crack is on the part where the can joins the pipe it needs welding.

BTW the Moggy has a tiny zorst compared to the Felly/Fabia!

They last about a week. On a modern exaust I doubt they would last a day as the higher flow and pressure would be problem. If the crack is on the part where the can joins the pipe it needs welding.

BTW the Moggy has a tiny zorst compared to the Felly/Fabia!

You think I don't know most of that?

Where do you think the higher pressure is coming from though? Remember that area, and hence flow volume per unit time rises as the square of diameter.

The extra heat might be a problem, but I've not needed to do one in 10 years or so, and the last one was done to get the car to run well enough to get it 70 miles to an exhaust centre.

You think I don't know most of that?

Where do you think the higher pressure is coming from though? Remember that area, and hence flow volume per unit time rises as the square of diameter.

The extra heat might be a problem, but I've not needed to do one in 10 years or so, and the last one was done to get the car to run well enough to get it 70 miles to an exhaust centre.

I appreciate that. I used to run Minis and Metros that would shake their exhausts to bits because of duff engine mountings meaning the required almost weekly patching until I could get the mounts done.

There is going to be a significantly higher flow of hotter gas than there would ever be coming out of a 27hp side valve engine as fitted to the MM. Diesels in general have a very high gas flow and even though the pipe is bigger (Therefore less pressure) I would bet that there was a higher pressure due to the volume of the gas.

If it's on the seam it will be a pain to get any repair like thus to stick to it.

I'd still give it a go though if I was stuck

I suspect you'd be right of a petrol turbo, but I know diesel turbo units run cooler than petrol ones do. And I was only saying that you might be surprised how long the repair would last, not claiming that it necessarily would last that long.

I suspect you'd be right of a petrol turbo, but I know diesel turbo units run cooler than petrol ones do. And I was only saying that you might be surprised how long the repair would last, not claiming that it necessarily would last that long.

Actually it's the cat that you need to worry about. They have very high operating temparatures sometime in excess of 500 degrees C. Diesel cats might not be that high but would still be quite warm!

Actually it's the cat that you need to worry about. They have very high operating temparatures sometime in excess of 500 degrees C. Diesel cats might not be that high but would still be quite warm!

Diesel cats are usually just oxidising units rather than 3-ways, aren't they? I'd have thought that would bring the temperature down a bit.

i welded the pipe back onto the back of the cat and braced it with a couple of bits of flat bar. three years ,two owners and a backbox later ,and its still going strong!

OK ..... in the end I bodged it twice - Gun Gum embarassment that lasted about 6 weeks round town and a 500 mile motorway blast! I had to bodge it again when the cat exit pipe snapped clean off. then decided to remove the downpipe to get it weled - centre section was seized solid and would not budge. Loads of grief later the car was off the road for two weeks and I end up with a new centre section and a custom decat stainless pipe (

I don't know the legalities of it, but AIUI a diesel can pass an MoT without a cat, and I would expect it to be free-er revving if not more powerful, as a result.

My neighbour is an MOT tester and reassured me it wouldn't be a problem (at least at his station...) . There is definately might be a performance increase, mid-range anyway - all relative I suppose as my commute vehicle is a 100hp 160kg bike....