Hi all, 

if anyone could give any advice I’d be very appreciative! 

I have a 13 plate Fiesta and have noticed rust developing on the bottom of the rear arches/ sill area (I would upload a photo but don’t seem to be able to) 

Do you think there will be more rust hiding underneath the factory sill sealant? Should I chip it back to see? 

How should I go about repairing it? I was thinking sand back all the rust, treat with rust inhibitor, prime, then spray with body colour paint, then coat the areas which had seam sealant before. It’s a bit tricky working with several different finishes all in one area! 
 
Thanks,

Josh
 

 

Hi all,

Just wanted to see if anyone has any advice or has encountered this problem? 

I’ve noticed some rust appearing on the lower rear wheel arches in the area where the arch meets the sill (see photos).

How would be best to go about repairing this, do I need to peel back the underseal on the sill to check for more rust? What paint should I use - I considered using black hammerite (as it is a fairly inconspicuous area) but there’s also bubbling on the bodywork above the sill which really should be repainted in body colour. 

Any advice would be much appreciated! 

Josh. 
 

 

If you’re going to do it then you may as well do it properly. If it’s something that you have any doubts about, even about the finished appearance it might be worth talking to the professionals and getting an idea of costs.

Totally appreciate that your car is approaching 10 years old, and the area you mention is a common area for corrosion to start. But Fiesta’s Mk 7’s don’t tend to be rust buckets when compared to cars of an earlier vintage. I think I paid £60 a side to have a similar clean up and repaint of my mums car at a local independent body shop. For the job they did I wasn’t with me getting dirty as I couldn’t have returned the car to a factory finish.

Remove the plastic deflectors and see what the bodywork is like behind them. Then clean with a wire brush, etc, treat, treat again, primer and paint.

Hi Andy, 

Yes I think the best finish will be done by taking it to a professional. My thoughts are it’s a 10 year old car so an immaculate, factory finish isn’t really necessary. Plus I also need to repair my door as someone tried to break in to it a few weeks back, so if I can save a bit of money doing it myself that will be ideal! 
 

Many thanks for getting back,

Josh

There's a few rotten Fiesta's on the road nowadays, our Fiesta is a 10 plate and been fighting the rust for several years now, some rust was not even apparent, but on removal of the seam sealer [that grey/white rubbery stuff] there was loads of rust developing behind it, after getting really fed up with it, this is the fourth time I've treated the sills, I used an angle grinder with a wire brush attachment, whipping off all the rust, treating the areas with hammerite, put loads on too, going to leave the hammerite to fully cure then I'll do a few light coats of the same colour, then re-lacquer it all.

Our local MOT test centre had an 12 plate in, the owner of the car was there and he allowed the mechanic to probe the ends of the sill, a screwdriver went straight in 😞 I think if I'd not been keeping on top of ours, that would have been the same too.

Top tip if you haven't access to a lift........Use a mirror to look at the rust, lay the mirror on the ground and position it under the sill, then simply look at the mirror.

Hi Ian,

Thanks for that. It seems weird that rust would develop under the sealant unless it’s spread from the areas that aren’t covered, or if it’s rusting from the inside? 

I’ve also found more rust developing on all corners where the plastic bumpers have rubbed through the paint on the quarter panel edges!😡

It’s my first car and I’ve always kept good care of it but will hopefully sell it on for something else in the next year or two. If I can just keep it at bay until then to get best resale value then I’ll be happy.

 

Why two separate threads about the same thing ?

1 minute ago, Ian Lanc said:

Why two separate threads about the same thing ?

there's too much rust to fit it all in to just one thread 🤣

I didn’t realise the first was published until the second one was! 

16 hours ago, JBOD said:

I didn’t realise the first was published until the second one was! 

In a rust to get it posted up 😛 😛 Ask Admin to delete the least interesting post/thread.

Hi, I know I'm a bit late to reply but I had a thread on this early last year. Exactly the same problem as you. Ending up putting a borescope in the sill, the rot was coming from inside. 

I ended up chopping it out and welding in a new rear of the nearside sill, still got the offside to do before next MOT.

When I got the old outer section off there was no seam sealer between the sill and inner arch, looked like water was entering this seam and the rot had started there from inside out. Not sure if it's a build date thing as mine is also a 2013 model.

 

The pic below is after the new section has been welded in, got a protective coating over it before filling and painting.

 

I saw a maroon 09 plate Fiesta yesterday, it was a mass of rust and had actually holed straight through the sill, the rotted hole was as big as the top of a bean tin lid 🥵

@rowly13 

wow yours is certainly worse than mine. I ended up sanding all the rust back, spread over kurust, then coated with hammerite anti rust paint and finally put over a layer of waxoil. Photos below show after sanding back and painting with hammerite. Just bought some primer, base coat and lacquer to finish off the parts of the sill which are body colour. I’ll probably also spray some cavity wax into the sill (which you can access via the rubber bungs underneath). Found the rear spring isolators were perished whilst underneath so onto those next - it honestly never ends😂

On 6/30/2023 at 8:25 AM, Ian Lanc said:

I saw a maroon 09 plate Fiesta yesterday, it was a mass of rust and had actually holed straight through the sill, the rotted hole was as big as the top of a bean tin lid 🥵

Do you just go round looking for rusty Fiestas😂

14 hours ago, JBOD said:

Do you just go round looking for rusty Fiestas😂

Sad actually but I do! I look for the rust then look at the plate reg' 08 plates are really bad.

The rust on ours, pics from about 2 maybe 3 years ago now, i've attacked this rust in numerous ways, always thinking I've won over it but it always comes back through, inside the wheel arch has been seriously treated with different types of rust treatments, all the hidden areas is now covered in thick grease, just plastered it on.

2 hours ago, Ian Lanc said:

Sad actually but I do! I look for the rust then look at the plate reg' 08 plates are really bad.

Guess they are 15yrs old now though

2 hours ago, Ian Lanc said:

The rust on ours, pics from about 2 maybe 3 years ago now, i've attacked this rust in numerous ways, always thinking I've won over it but it always comes back through, inside the wheel arch has been seriously treated with different types of rust treatments, all the hidden areas is now covered in thick grease, just plastered it on.

Did you get all the rust off in the first place and did you neutralise it? Will be interesting to see how long mine lasts. The rust shouldn’t be able to progress without exposure to air/ water so was it sealed off correctly? I’d imagine if you just left it with body colour paint the rocks and grit would chip it off in no time, hopefully the grease you’ve put on will stop the paint from chipping underneath. 

This is what was cut out. The arrow points to the first bung hole from the rear and this is where the rust pretty much stopped. I carried on just past that hole.

Would of never thought it was coming from inside out until I got the camera in there and then cut it out. Didn't look that bad from the outside at all. Just a couple of blisters.

3 hours ago, rowly13 said:

This is what was cut out. The arrow points to the first bung hole from the rear and this is where the rust pretty much stopped. I carried on just past that hole.

Would have never thought it was coming from inside out until I got the camera in there and then cut it out. Didn't look that bad from the outside at all. Just a couple of blisters.

Wow that’s bad. Do you live near the sea? 

I do actually. But I only got hold of the car this year and it spent it's first 9 and a half years away from the sea. Really is shocking for a car of this age.

Good news is the rest of the sill looked good inside, was just the rear section where it looked like salty water had been entering through seam that I can't believe they didn't seam seal. All the wheel spray goes directly onto it.

 

17 minutes ago, rowly13 said:

I do actually. But I only got hold of the car this year and it spent it's first 9 and a half years away from the sea. Really is shocking for a car of this age.

Good news is the rest of the sill looked good inside, was just the rear section where it looked like salty water had been entering through seam that I can't believe they didn't seam seal. All the wheel spray goes directly onto it.

 

Are you talking about the seam that runs up the wheel arch from the sill?Strange how yours doesn’t have sealer as mine does. 

Yeah the join from the inner arch panel to the very end of the outer sill where it turns 90 Deg towards the car. No seam sealer joining the 2 pieces together on mine. I expected to see it bonded instead but when I drilled out the spot welds there the piece of rusty steel just fell off, no sealer at all. Looked like it had all started from there, was less and less rusty the further away it got from that point.

9 hours ago, JBOD said:

Did you get all the rust off in the first place and did you neutralise it?  

You wouldn't believe what I've been doing to keep the rust at bay, yes I removed all the rust, got through several bottles of that kill rust stuff, that stuff that turns black, I've even Etch primed the metal, then several good layers of spray primer filler, then standard primer on that, followed by two layers of base green, then two layers of clear lacquer, it looks fab again but give it a year and I can see the rust coming back, it appears to be coming from the welded edge of the steel, how the sills look underneath, that pic is from the second run of cleaning off the rust & repaint. 

On my latest repaint I've pushed vinyl tubing up in the holes and forced engine oil inside, using a large syringe allowing the oil to run out everywhere, made a right mess but might stop the rust this time which i think is developing from the inside.