MOT failures for corrosion are common on working vans.
They are also often misunderstood.
This Ford Transit came to us after failing its MOT due to corrosion on the sills.
What looked like a simple repair quickly showed why proper welding matters.
This post explains what failed, what we found once work started, and why cutting corners on welding costs more in the long run.
If you run a van for work, this applies to you.
The vehicle and the MOT failure
The vehicle was a 2013 Ford Transit.
A hard-working van that had seen years of use.
The MOT failure listed corrosion on the outer sills.
On paper, the repair sounded clear.
Replace sections of the outer sill and move on.
Real repairs rarely stay that neat.
Once the affected areas were cleaned back, the true condition became visible.
The corrosion did not stop at the outer sill.
The inner sill had also started to break apart.
This is where experience matters.
You only see the full problem once you expose clean metal.
Why sill corrosion spreads
Sills trap moisture.
Road salt builds up.
Drainage holes block.
Over time, corrosion works from the inside out.
Outer panels can look presentable while the structure behind them weakens.
Cutting out only what you can see leaves rot behind.
That rot continues to spread.
On this Transit, cleaning back the metal caused parts of the inner sill to break away.
That told us one thing.
A patch over the top would not last.
What the repair actually involved
The MOT failure called for two new front section outer sills.
Once work began, inner sill repairs became part of the job.
The repair process followed a clear order:
- Cut out all weakened metal until solid structure was exposed.
- Assess inner sill strength before fabricating repair sections.
- Fabricate replacement panels to match original structure.
- Weld repairs fully, not stitched or tacked.
- Dress welds and protect the metal correctly.
This is slower than plating over rust.
It is also the only way the repair holds.
Why MOT welding needs to be structural
An MOT tester checks structure.
Not cosmetics.
If corrosion affects load-bearing areas, repairs must restore strength.
Thin patches welded onto rust do not restore strength.
They hide weakness.
On a van like a Transit, sills contribute to rigidity.
They support jacking points.
They protect occupants.
Welding must tie into clean, solid metal.
Anything less is a short-term fix.
Qualified welding makes the difference
Welding on vehicles is not all the same.
Structural work demands skill and certification.
Our welders are B6 and 6G MIG and TIG coded.
That matters when repairs affect structure.
It means weld penetration, strength, and consistency are controlled.
We also offer aluminium welding for vehicles that need it.
This comes up more often on newer vans and specialist vehicles.
For dedicated welding work, fabrication, and structural repairs, we work alongside our sister company:
Star Welding Mansfield.
Keeping this work specialist protects quality.
Why cleaning back metal reveals the real cost
Many drivers ask why welding quotes change once work starts.
The answer is hidden corrosion.
Until rust is removed, you cannot see where solid metal begins.
On this Transit, cleaning exposed further damage.
Ignoring it would have left weakness behind the repair.
Honest welding work adapts to what is found.
That protects the vehicle and keeps it compliant.
How this fits into general repairs
Welding repairs often sit alongside mechanical work.
Brake pipes.
Mounting points.
Suspension fixings.
This is why we treat corrosion as part of our wider
general repairs
service.
Fixing one issue while ignoring surrounding problems leads to repeat visits.
On working vans, downtime costs money.
Getting repairs done properly first time keeps you on the road.
Protecting repairs after welding
Welding is only part of the job.
Protection matters just as much.
After repairs, metal needs:
- Correct treatment to prevent moisture ingress.
- Seam sealing where required.
- Protective coatings applied properly.
Skipping this stage shortens the life of the repair.
The goal is not just to pass an MOT.
The goal is to slow corrosion returning.
Common signs your van may fail for corrosion
Do not wait for an MOT failure to take action.
Early signs include:
- Flaking metal around sills or arches.
- Crunching sounds when jacking.
- Previous welding plates starting to rust through.
- Advisories repeating year after year.
Catching corrosion early reduces welding time and cost.
The finished result
Once repairs were complete, the Transit had solid structure restored.
The MOT failure was addressed properly.
The van was safe to return to work.
Jobs like this do not look dramatic once painted.
Their value sits underneath.
In strength.
In safety.
In longevity.
That is what proper welding delivers.
When to book welding repairs
Book an inspection if:
- Your MOT lists corrosion advisories.
- You can see rust near jacking points.
- A van is used daily for work.
Early assessment gives you options.
Waiting removes them.
If you are local to Mansfield or Mansfield Woodhouse, get in touch via our
contact page.
We will explain what needs fixing, what can wait, and what keeps your vehicle legal and safe.
Structural corrosion fixed properly keeps vans working.
That is the difference between a short-term patch and a repair that lasts.
Need this looked at?
Describe the symptom and we’ll tell you whether it needs a diagnostic slot or a straight booking.
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