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Treating rust in hard to reach area...wheel arch.



conor1n

ClioSport Club Member
  PH2 172 Cup - Track!
Hello guys,

So I am wondering if you can help me with this.. My Mercedes SL has the well known rear arch rust issues and it needs work. The photo below shows the damage. From an inspection, that bubbling is mainly just the paint and surface rust, not deep rust. I can pull at the lip and the structure doesn't come away (yet!!).

Anyway the inside is the main affected area and I am wondering about how to go about treating it.. my options seem to be:

a) "Convert it" with chemicals.
b) "Remove" it with chemicals.

What would you guys recommend? I would need a gel as opposed to liquid.. Once the inner bits are treated I would seal the area up and seal the entire lip so no more sludge can settle.

Does anybody have a playbook/guide for this kind of job?

* For the outside and accessible areas, I will just use a Dremel with flapwheel / wire brush / whatever is needed.. and level off with filler, before priming and attempting to colour match etc.. If the painting goes all tits up I can outsource it lol.

Thanks a lot!

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Patrick Bateman

ClioSport Club Member
  Clio Trophy
In my experience this will be guaranteed to come back before long unless you get a bodyshop that really knows what they're doing.
 

conor1n

ClioSport Club Member
  PH2 172 Cup - Track!
In my experience this will be guaranteed to come back before long unless you get a bodyshop that really knows what they're doing.
Not an unreasonable comment... but I have been researching a lot and plan on using Bilt Hamber rust remover then their treatment after that before paint.

I have studied it a lot and have the process down.. just a case of whether I execute it properly.

Thing is...i've had plenty of lowball offers from shop, who are sure to just paint over which will result in re-occurrence. One place that was going to treat properly with acid wash etc wanted £1600 or something.

I believe Bilt Hamber is good, so happy to give it a shot myself considering it won't be taken out in the rain etc.

But like you say, time will tell..
 

conor1n

ClioSport Club Member
  PH2 172 Cup - Track!
Wheels off, archliners out, bumper off and get a better look. Should have plenty of room
Yea, exactly that.

Open the whole lot up, inspect, then grind/flap off the large rust. Then treat with Bilt Hamer Deox Gel, wash off with Bilt Hamber Surfex HD then apply some Bilt Hamber Hydrate 80.. the some Epoxy Primer, Paint and Waxoyl inside..
 

Patrick Bateman

ClioSport Club Member
  Clio Trophy
Yea, exactly that.

Open the whole lot up, inspect, then grind/flap off the large rust. Then treat with Bilt Hamber Deox Gel, wash off with Bilt Hamber Surfex HD then apply some Bilt Hamber Hydrate 80.. the some Epoxy Primer, Paint and Waxoyl inside..
I would advise buffing off all the rust thoroughly and then using the gel to give yourself the best chance of longevity. It's good stuff but it has limits.

I've touched up small areas (see attached picture) before, getting the worst of the rust off thinking that'll do and then relying on the gel to remove the last of it but it didn't last long. That was using the electrox primer too.

Would also be as well going with a Bilt Hamber wax rather than cheap waxoyl. I reckon if a good bodyshop were to thoroughly prep something like that correctly then use the Bilt Hamber products you've described it might have a fighting chance of lasting a decent while.

I say this as someone who's had 3 different bodyshops remove rust on different cars by just buffing it away, came back every time before too long.
 

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Brigsy

ClioSport Club Member
  Kangoo 172cup
Take the paint off until back to good metal, then keep coating it with BH deox gel until the metal is totally shiny with no pits, will need to do the inside of the wing too. Once you have achieved that, zinc or epoxy primer on all prepared surfaces, followed by top coat.
 

BaileyWolves

ClioSport Club Member
  Clio 172 Cup
Depending on ur long term plans get a body shop to cut the arch and replace, I did both the rears on my cup it’s a peice of mind that it’s not coming back
 

conor1n

ClioSport Club Member
  PH2 172 Cup - Track!
I would advise buffing off all the rust thoroughly and then using the gel to give yourself the best chance of longevity. It's good stuff but it has limits.

I've touched up small areas (see attached picture) before, getting the worst of the rust off thinking that'll do and then relying on the gel to remove the last of it but it didn't last long. That was using the electrox primer too.

Would also be as well going with a Bilt Hamber wax rather than cheap waxoyl. I reckon if a good bodyshop were to thoroughly prep something like that correctly then use the Bilt Hamber products you've described it might have a fighting chance of lasting a decent while.

I say this as someone who's had 3 different bodyshops remove rust on different cars by just buffing it away, came back every time before too long.
Found the photo of what it was like before selling the car.
Hmm.. interesting. A cautionary tale.

The thing about going to a bodyshop is that most of them were providing quotes that were "too good to be true", which were in the region of 500-800 mark... in London. They are definitely going to be superficial repairs.

Only one guy, up in Essex new about the rust issues and mentioned acid wash etc all. I have no doubt he would do a stellar job. But I just really don't want to pay £1500 for the job. Some might say that is foolish.

I believe I will be able to do an ok job, which I believe if done alright should be a permanent fix. If not, I will have all the materials and it will only take time the next time. It is a summer car so won't be going out in the wet, so happy to take a gamble. I live for self learning and DIY, and willing to accept the downsides of that too.

Take the paint off until back to good metal, then keep coating it with BH deox gel until the metal is totally shiny with no pits, will need to do the inside of the wing too. Once you have achieved that, zinc or epoxy primer on all prepared surfaces, followed by top coat.
Yes. That's what I plan on doing.. plenty of applications. The only concern I have is on the inside there is a lip that I won't be able to see into..

Depending on ur long term plans get a body shop to cut the arch and replace, I did both the rears on my cup it’s a peice of mind that it’s not coming back
I don't think that is necessary.. I do plan on keeping the car but I won't be doing that lol. The rust is very superficial at the moment. And I don't think it's gone through. Will know more when I go at it..
 

conor1n

ClioSport Club Member
  PH2 172 Cup - Track!
... I was supposed to be working on this yesterday and today... On Wednesday evening I was driving to collect the Bilt Hamber bits and the alternator gave up in my daily :/
 

BaileyWolves

ClioSport Club Member
  Clio 172 Cup
My inners were totally gone which is why I went down that route you just hear every person rust never disappears lol it always rears it’s ugly head
 

conor1n

ClioSport Club Member
  PH2 172 Cup - Track!
My inners were totally gone which is why I went down that route you just hear every person rust never disappears lol it always rears it’s ugly head
Yea I hear that too... but at the back of my mind is the fact that rust is basically metal oxidation..meaning oxygen is part of the issue. I wonder if most unsuccessful jobs, are due to some level of porous..?

I mean.. if you had a piece of rust in a completely epoxy sealed covering..would it continue to rust. It's a hypothesis that I don't know the answer to..

If I do this and it comes back in 5 years I won't mind. If it comes back in 6 to 24 months that will be annoying, but anything else will be ok.. I will just monitor it.
 

Brigsy

ClioSport Club Member
  Kangoo 172cup
I think most rust jobs fail as not cleaned up properly, you need to clean the metal up so there is no pits at all, and deox gel does it really well, but its the waiting game.

I would personally take all the arch liner out, or wing off if needs be to do it right to get the back
 

1985michael182

ClioSport Club Member
  clio 182
Quick answer, weld new metal in. Mercs are shite for rust in these areas. 100% will be rusting inside the flange where the inner and outer are spot welded together. You won't stop no matter how clean you get the outside. Looking at how heavily corroded it already is theres going to be holes when you grind the top off. You should be able to get repair panels rather than a full new 1/4. I did this on an e46 330d I bought to sell. It only had 50000 miles on but was cover in rust. Interior was immaculate. Bought it for £200 spent around £700 doing it up sold it for £2500. Maybe had 20 man hours in it.
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If your asking yourself how does this jobs worth know, senior ATA BMW panel technician 🤓
 

Patrick Bateman

ClioSport Club Member
  Clio Trophy
That looks like a cracking job.

Biggest issue I've found are bodyshops who are actually willing to cut out and replace sections of metal.

I have some bubbling in a rear arch on the Trophy, had a place in mind to use who did a lot of high end, older stuff and were used to this kind of thing and now I see they're permanently closed according to google!
 

1985michael182

ClioSport Club Member
  clio 182
How much is a 1/4 on a clio? Anyone know?

That e46, the repairs I did are not following any manufacturer methods or thatcham methods but the steel used in the older stuff it's not going to make any difference in a collision. Let's face it new fresh steel will react better than rotten on crap! I would be more than happy to put my family in it and be confident in the structure.
The trade in general is dying off, insurance companies are killing body shops with low ball hourly labour rates.
Our service techs are charged out at £140 per hour and techs in the Bodyshop average £34 per hour. Its bull s**t!
No apprentices coming into the trade either because nobody wants to graft these days so there going to be a limited future for the trade. They all want to duck about with YouTube and blogging shite!
Rant over 😁
 

conor1n

ClioSport Club Member
  PH2 172 Cup - Track!
How much is a 1/4 on a clio? Anyone know?

That e46, the repairs I did are not following any manufacturer methods or thatcham methods but the steel used in the older stuff it's not going to make any difference in a collision. Let's face it new fresh steel will react better than rotten on crap! I would be more than happy to put my family in it and be confident in the structure.
The trade in general is dying off, insurance companies are killing body shops with low ball hourly labour rates.
Our service techs are charged out at £140 per hour and techs in the Bodyshop average £34 per hour. Its bull s**t!
No apprentices coming into the trade either because nobody wants to graft these days so there going to be a limited future for the trade. They all want to duck about with YouTube and blogging shite!
Rant over 😁
That looks like an awesome job you did there!
 

MRBILLYUK

ClioSport Club Member
  FF Jeden Osiem Dwa
Quick answer, weld new metal in. Mercs are shite for rust in these areas. 100% will be rusting inside the flange where the inner and outer are spot welded together. You won't stop no matter how clean you get the outside. Looking at how heavily corroded it already is theres going to be holes when you grind the top off. You should be able to get repair panels rather than a full new 1/4. I did this on an e46 330d I bought to sell. It only had 50000 miles on but was cover in rust. Interior was immaculate. Bought it for £200 spent around £700 doing it up sold it for £2500. Maybe had 20 man hours in it.
View attachment 1454703View attachment 1454704View attachment 1454705View attachment 1454706View attachment 1454707View attachment 1454708View attachment 1454709View attachment 1454710


If your asking yourself how does this jobs worth know, senior ATA BMW panel technician 🤓
So for £700 your body shop will cut out then weld in new metal , repaint the side of the car including doors ?
That's cheap.
 

1985michael182

ClioSport Club Member
  clio 182
So for £700 your body shop will cut out then weld in new metal , repaint the side of the car including doors ?
That's cheap.
Haha no chance, that's what I payed for parts, paint and material, 2 new front wings I fitted aswell. Obviously that was not including my man hours. I bought it originally to tow the clio, but ended up selling it to pay for an M3 competition pack for 6months through work 🤤
 

MRBILLYUK

ClioSport Club Member
  FF Jeden Osiem Dwa
Haha no chance, that's what I payed for parts, paint and material, 2 new front wings I fitted aswell. Obviously that was not including my man hours. I bought it originally to tow the clio, but ended up selling it to pay for an M3 competition pack for 6months through work 🤤
Ahhh I see. I thought £700 for all that work was cheap o_O
 

1985michael182

ClioSport Club Member
  clio 182
I work at a main BMW dealer. Theres a staff car scheme where you can have any car you want for 6months at a time. I sold the e46 to pay for the M3 for 6months. Think it was £418 per month. That included road tax, so all i needed to do was insure it and put fuel in. I also had an X120d through winter then a 140i the next summer then a mini countryman all4 2.0d. Now I've bought an X3 30d to tow the clio with. Came in at the right price with an electric tow bar fitted from factory
 

conor1n

ClioSport Club Member
  PH2 172 Cup - Track!
I work at a main BMW dealer. Theres a staff car scheme where you can have any car you want for 6months at a time. I sold the e46 to pay for the M3 for 6months. Think it was £418 per month. That included road tax, so all i needed to do was insure it and put fuel in. I also had an X120d through winter then a 140i the next summer then a mini countryman all4 2.0d. Now I've bought an X3 30d to tow the clio with. Came in at the right price with an electric tow bar fitted from factory
Nice perks, getting to try out loads of cars. Do you need to pay BMW at all or was the sale of the e46 to for fuel/insurance?
 

1985michael182

ClioSport Club Member
  clio 182
So the £418 came out of my wage before I was paid so the money from the e46 replaced it each month. Basically worked out I had the M3 for free. Was the summer I got married so had it for our wedding aswell.
 


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