Further investigation into my 205's exhaust system revealed that the short bit of pipe from the Cat to where it joins the middle section had actually gone porous. This was the original 1996 Cat (at least I had never replaced it in my ownership since 2007). Just before the test centre closed for lockdown in March I had failed for high lambda reading which I believe is almost always down to an air leak into the exhaust which was why I was looking at this in detail. The Cat was much heavier grade steel than the rest of the exhaust system which is why it's outlasted several exhaust systems and it hadn't blown a hole in it or wasn't weak enough to push holes in it but what seemed like light surface rust when cleaned away was actually very deep pitting.
Several exhaust centres said it was impossible to buy a new Cat and suggested all sorts of bodges but I was able to find an online source. I paid the extra for an approved branded Cat with a guarantee as a mechanic friend told me that the really cheap spurious ones only last a few weeks.
So today I fitted my new Cat. What I hadn't realised when I ordered it was that the middle section of the exhaust came with it too so I fitted that too. The back box had been replaced last October so I now have basically a new exhaust front to back and I replaced all the rubber mountings too. I have always left exhausts to the exhaust centres in the past but in reality it was very easy and straightforward (helped by the 205's generous ground clearance by modern standards. The time-consuming bit was undoing the two flange bolts at the front which were tight, rusty and had about 1.5" of unnecessary threads and took an age to undo as I had only room for about 1/4 turn at a time reaching down the back of the engine. Why Peugeot felt the need to use such long bolts is a mystery to me. I was hoping they'd snap off as the new Cat came with replacements but they had to be unscrewed right to the bitter end.
The difference in refinement when I drive the car is unbelievable. It must have gradually got noisier without me realising! It was the one genuine improvement I did see when comparing the 205 to the Fabia - the Fabia's engine is much quieter at speed. Now I don't think there is any real difference now that the 205 is as it was supposed to be.
I think there was a design fault in the exhaust system on the 205. The exhaust is not supported at the joint with back box so it is difficult to keep this joint sealed in my experience as the weight of the back silencer is resting on the joint.
I also rectified another irritation. My car had been rear-ended in the past and the boot lid replaced so it had a different key to lock it. Early last year the ignition barrel screwed up so I fitted a replacement so I had a situation where I needed a key for the boot, a key for the front doors and and a key for the ignition so I bought a complete lock set from
Ebay and fitted it today as well. Unfortunately it didn't come with a petrol cap or the glovebox lid lock (to be fair mine is one of the very few 205 I have ever seen with locking glovebox. It must have been an optional extra) so I still need the original key but I will leave it in the car. I now only need one key to unlock the door, open the boot or start the engine
I will get a spare cut too. The advantage of owning a pre-immobiliser car is that I can get a spare key in the locksmith's for peanuts