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Old 29-08-2017   #16
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Location: Chesham, Bucks
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Re: replacement of front exhaust catalytic converter

Thank you again.

I managed to finish the job - almost correctly!

What I almost didn't do - and would most likely cause big problems - is fit the metal compression gasket/ring which sits on a groove on the star-shaped flange of the new cat.

I didn't know those things existed, and I noticed almost by coincidence by comparing the old cat with the new one...

Anyways, I simply reused the old compression ring as it looked allright.

With regard to the fact that the two longest studs in the new exhaust were not long enough, what I did is I managed to unscrew them from the old cat, and again I re-used them as they were not rusty nor the thread was damaged. Perfect!

Then I made sure the two surfaces were very clean, spotless, and I proceeded to tighten 5 new stainless steel nuts to the 5 studs, going in a star pattern. I did not add any exhaust putty/paste because there was no trace it had been used, and I don't think it was needed (I had not yet read your post!). I also I feared it could make the seal less good if applied incorrectly... We'll see!

Finally I tried to join the front downpipe with the middle pipe flange, and here's where I did it wrong and will need to re-do it as soon as I have some time in the next few days. At the moment the car sounds like it's a tractor...

I think the main problem is that - once again! - I had not noticed that there was a compression ring/gasket on the cat side flange that joins with the middle pipe flange...

So all I did was put a wire-brush head on the drill and clear the rust and old putty on the mid-pipe flange, then applied some exhaust paste on both flanges and screwed them together with the two bolts + nuts. However the seal must be almost non-existent going by the noise it makes...

Now I ordered a new compression ring (the old one looks rusty, so I want to use a new one), as well as the whole mid-pipe for 26 quid. I thought as it looks pretty rusted I might as well change it while I'm at it...

Is there anything else I need to be aware of? For instance, should there be a gap between the two flanges? Because there is a small gap, about 1mm, at the moment, and I don't think that's right. Do Mareas 1.6 take an exhaust flange gasket like the 2.0 seem to (I saw this on ebay: http://www.ebay.co.uk/itm/FIAT-Marea...-/290579985075).

Once I fix this, I will be able to tell whether the cat is correctly attached to the manifold: at the moment the joint between downpipe (with cat) and the mid-pipe makes such a racket than I can't hear whether there is any noise coming from upstream...

Thanks again.
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Last edited by lukish; 29-08-2017 at 11:18.
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Old 30-08-2017   #17
Join Date: Apr 2013
Location: Chesham, Bucks
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Re: replacement of front exhaust catalytic converter

Is adding a flange gasket (with or without the stock compression ring) going to improve the seal between the cat downpipe and the mid-pipe?

I've noticed that some Marea (and Bravo/a) models use only the compression ring, and some use only the flange gasket for that joint. The flange gasket ePer number is 46459258 (the compression ring is 46753222).

Are they interchangeable? If so, does anybody know what's best please?

Cheers
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Old 30-08-2017   #18
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Re: replacement of front exhaust catalytic converter

Quote Quote:
Is adding a flange gasket
If by compression ring you mean an exhaust flange olive (photo attached) you could have re-used the old one. They don't actually compress as such - they provide a tapered fit for the flanges. Though having said that, a new one isn't a bad idea.

You can use exhaust paste on the olive. When you tighten the flanges the pipes/flanges will pull down onto the tapered part of the olive. There's nothing wrong with using an olive even if the original system didn't have one.

If the new exhaust is leaking/noisy it's simply because the flanges are off-centre or not mating properly. It's no big deal and easily rectified.

The biggest problem for the home mechanic replacing an exhaust system is the actual crawling under and rolling around beneath the car. If it was up on ramps that you can stand under, it would be a different ball game .. but .. for the home mechanic ...

I changed the rear exhaust section on my 4 litre jeep. I simply used an angle grinder to cut through the old U-clamps, hit the rear box with a hammer until the pipe flanges separated and again used the angle grinder to cut through the rubber 'hangers' (replace all parts with new..).

When it came to fitting the new exhaust rear section ... I honestly thought I'd been supplied with the wrong part. It took ages to get it into place - I was lying underneath the jeep cursing Jeep, the Gods, the exhaust manufacturer...

..and no matter what, the two flanges wouldn't mate together properly which made the exhaust sound like a tractor .. Eventually I shoved an old olive in and used some exhaust paste, which did the trick..
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