Replacing middle and back box on exhaust.

[Brendan976]

Hi

Exhaust was leaking from middle section and back box. I replaced both sections from the catalytic converter to the back box. I tend to use Holts exhaust assembly paste on joints. I put a generous amount on the cat to middle section tightened up the nuts on the three studs. I then installed a new

[Brendan976]

Sorry some how it cropped a lot of text which make the message hard to understand. I had written that I had used Holt exhaust paste to seal the joints tested  it and no leaks were found. During a random search on eBay I came across a gasket kit for the Jazz that had a gasket for the middle section to catalytic converter. Did the cvt 1.4 gd1 2004 come with exhaust gasket installed?

[Jocko]

There is a gasket for each of the joints. Item 16 is the one to the cat 13 between the front and backbox.

[Brendan976]

Thanks Jocko

Item 13 I have installed, 16 is missing but appears to have sealed correctly ie no leaks. I will leave it as it is for now. The three studs are almost corroded through and I fear they will shear off. I have totally covered the studs and threads with copper ease to try and prevent further corrosion. If a leak appears I will then tackle it.

[Lord Voltermore]

I'm not sure how long sealant will last without a gasket once it hardens and is  subject to vibration and pressure.  But you may be lucky.     

Copper ease may help but you wont know it has worked until you try undoing the nut.  Its best to assume at least one  stud will shear. I wouldnt even try unscrewing the nuts ,but cut them off using a nut splitter  , like this .

https://www.toolstation.com/nut-splitter-set/p80007?store=M4&utm_source=googleshopping&utm_medium=feed&utm_campaign=googleshoppingfeed&mkwid=_dc&pcrid=560396161865&pkw=&pmt=&gclid=CjwKCAiAh_GNBhAHEiwAjOh3ZEcSJJ1V3MPIf2UHIf1ZAWQT3-pkPSK7HAuVqtyONLBWNsR61XWHcxoCnd4QAvD_BwE&gclsrc=aw.ds

This should leave the stud intact  ,which would be easier to extract if necessary  . With luck you may only need  replacement nuts, which are readily available.   

[Brendan976]

I have a nut splitter, I was able to remove all the nuts from the studs using loads of penetrating oil over numerous applications. I then used patience and a 6 point socket using slow loosing and tightening back and forth movements. So the nuts are ok, I cleaned the threads, removed all the rust and that’s when I identified the damage caused by the rust. I would be a real pita to drill out the studs.  The cat would have to be removed as access to one of the studs would be impossible to drill in situ?

[Jocko]

I had a very similar problem with the nuts being just blobs. I just elected to replace the cat, lock stock and barrel. Middlebox getting replaced again on Monday (5 years on and a hole in the pipe where a bracket is attached). I just hope things separate easier this time.

[degzi]

  my centre pipe has gone too. A fix for over Xmas.

I'm sure Part 16 is like a big washer.

[Brendan976]

I stand corrected the washer is in fact attached to the old middle section. The washer is welded to the pipe. I will look for the correct washer and install it if/when it leaks.