Something else I needed to fit was a new mid silencer on the Zafira, since the rubbish the garage fitted split along its plated seam after less than a year.
Luckily the new section I have is “rolled” instead of “pressed” meaning it only has one long edge seam instead of two physical sections tacked together. So my plan for this is just to give the product more protection from the elements, it’s mild steel and it will fail eventually but it might help a little…
Versachem is a good product, and it is a strong sealer so I have applied it to all the seam edges on the box, notice how it’s embedded into the small gaps nicely…
Here is another example on the recesses, this only took about five minutes skimming the versachem wearing latex gloves (seriously use gloves as versachem is rather potent stuff).
Spraying is also a rather quick task, since this is matte VHT it tends not to run so bad and even one coat looks rather tidy. Also it can be good to tape the edges to give a cleaner finish (not that anyone will see this work of art lol).
After fifteen minutes I applied another quick coat.
I applied the paint mostly to the ends and on the long seam edge, after five minutes of drying you see it goes to this flat matt colour and does not look too bad at all. To finish I sprayed the hanger sections also just to help protect the welds.
That concludes my little DIY post here on a little rust/corrosion protection for budget exhaust components, have a good day 🙂
In principal this is quite a simple job and you don’t really need to be mechanically minded to do this at all, what makes it a pain is rusty nuts ! Be prepared for those rusty nuts from hell ! In this post I will just outline some tips when it comes to replacing the cat for this specific vehicle as it might come in useful for others out there.
So it’s been fifteen years and 65k miles for my Dad’s Zafira, I guess it’s going through the “bits are wearing out” kinda stage. The vehicle has been flawless but in the last year the following have happened:
Exhaust muffler blow – Replaced
Exhaust mid silencer blow – Replaced
Downpipe flex collapse – Replaced
Primary and Secondary o2 sensor failure – Replaced (use genuine NTK/GM/Bosch/Denso or you might get EML issues!)
And now the latest addition: “P0420 – Catalyst System Low Efficiency” ! Eeekk
So this is the best answer I found to removing all the manifold nuts. This is a tool known as a “nut/bolt extractor” and is essentially a sharp spiral teething socket that grips into rusted nuts or bolts and gets them loose ! The ones I went for are the “Irwin Bolt Grip Expansion Set” which has the correct 10mm fitment for the Zafra/Astra G. I would not of got the job done without these they are perfect for this job. It is possible to do the nuts off with a chisel and a hammer but the “Irwin’s” save loads of time and risk of damaging the stud threads.
Would you like to see what happened to the old catalytic converter ? Well here you are, no wonder it wasn’t do it’s job most of the monolith element was gone ! As you can see it is a really chalky colour which is a sign of fatigue and heat damage, 17 years though cannot complain !
There is not much else to mention apart from some tips regarding the new cat. I purchased an “eBay approved cat” costing £100 but there are some differences to note against the OEM GM cat !
Firstly as you can see in the photograph the bottom down pipe connection has bolt holes instead of integrated studs. This is fine apart from the Screws/Nuts supplied are absolute rubbish ! I don’t know what they are but the nuts have weird dipped threads so when you are putting the nuts on they suddenly go extremely tight, and it’s impossible to do laying under the car using a socket in one hand and a spanner in the other !
My advice is ditch the provided Screws/Nuts and pick up the Halfords M8 assortment pack for £3.48 they are perfect for the job and save a lot of hassle !
Also another mention which is unavoidable really but still a bummer and that’s the manifold casting shape. Basically the new one has slightly shallower header branches, if you look carefully on the photo above you will see the far right branch is a fatter shape and this makes the far right bottom nut really damn hard to fit ! The only way I could get it done was to remove the oil filter, and even after that it took about half an hour to fit the damn nut with an open end spanner !
So just to conclude this task:
- Get nut/bolt extractors to make removal much easier
- If you can pickup a new or very good genuine OEM GM cat it will be easier to fit !
Hope this help anyone out there, leave a comment if you have any questions.