Before you buy a van to convert, check three things in this order: the payload on the weight plate, the structural metal for rust, and the service history for the expensive jobs like the timing belt and gearbox. Everything else you can fix or live with. Those three decide whether you are buying a good base or a money pit with a fresh coat of paint.
We learned this with Boxie, our Peugeot Boxer. We fell for a tidy interior and a clean dashboard and almost talked ourselves past the rust creeping along one sill. It worked out, but we got lucky, not clever. This is the checklist we take to every viewing now, in 2026, after making most of the mistakes ourselves.
What is the one number that matters most?
The payload. It is the weight you are allowed to add to the empty van, and it quietly decides whether your finished camper is even legal. Find the plate, usually in a door frame or under the bonnet. It lists the gross vehicle weight, often 3,500 kg, and the kerb weight. Subtract one from the other and that is your payload.
Here is why it matters so much. A full conversion adds roughly 300 to 600 kg once you count insulation, furniture, water, a leisure battery and your own gear. If a van leaves the factory with only 800 kg of payload, you are already close to the edge before a single passenger climbs in. We wrote a whole piece on where that weight hides, because it caught us out too.
How much rust is too much?
Surface rust is normal and cheap to sort. Structural rust is a different animal, and it is usually a reason to walk away. Run your eyes, and a hand, along the sills, the wheel arches, the lower door edges, the load-area floor and the roof seams. Bubbling paint means rust is already working underneath it.
The real test is where the rust sits, not how much orange you can see. Flaky rust on a panel you can treat in an afternoon. Rot on the chassis rails, the suspension mounts or the sills that carry the body is structural, and a proper repair costs more than most first vans are worth. Bring a magnet and a torch. Filler smoothed over rot will not hold the magnet.
Which paperwork actually tells you something?
On a diesel, service history beats mileage every time. A van with 250,000 km and a folder full of stamps can be a safer buy than a 120,000 km van with nothing. Look for the jobs that cost real money when they are skipped: the timing belt, or proof the engine runs a chain, the gearbox oil, the brakes, and any work on the emissions system.
Then read the MOT or APK history for a pattern. Advisories that repeat year after year, like the same weeping brake pipe, tell you what the seller has been quietly ignoring. A clean recent test sitting on top of a long list of past failures is worth a closer look, not blind trust.
What should you do on the test drive?
Start it cold. A diesel that has been warmed up before you arrive can hide a rough cold start, so ask the seller not to run it first. Watch the exhaust on start-up and under acceleration. Blue smoke is burning oil, white smoke that lingers can point to a head gasket, thick black is a fuelling problem. A little haze on a cold morning is nothing to worry about.
Then drive it properly. Every gear, up and back down. Listen for whining or crunching, and feel whether the clutch bites right at the top of the pedal, which hints it is near the end. Check that every dash light goes out, especially the engine management, the DPF and the AdBlue warnings on newer diesels, because those are the repairs that empty a build budget fast.
Is the van the right size for the build you want?
Decide how you want to sleep before you fall for a van. If you want to lie across the van rather than head to toe, you need the internal width for it, which usually means a longer wheelbase. If you want to stand up straight inside, you need a high roof, not a medium one. Measuring this at the viewing saves you from designing a layout that was never going to fit.
The common first-build vans make this easy, because their dimensions are so well documented: the Peugeot Boxer, Citroen Relay, Fiat Ducato, Mercedes Sprinter, VW Crafter, Ford Transit and Renault Master. Payload plates, parts and conversion measurements for all of them are a quick search away.
A clean interior sells the van. The payload plate, the sills and the service folder tell you whether it is worth buying.
Should you pay for a professional inspection?
For an older diesel, or a van near the top of your budget, yes. An independent pre-purchase inspection costs a fraction of a hidden gearbox or injector repair, and a good inspector checks the things you cannot see from the driver's seat. If the seller will not let you arrange one, treat that as your answer.
If you want the full viewing checklist in your pocket, next to the buying, tools and pre-build lists we put together after getting some of this wrong, it is all in the VanMate package.
Frequently asked questions about buying a van to convert
What payload do I need for a camper conversion?
A finished conversion usually adds 300 to 600 kg, so look for a van with at least 800 to 1,000 kg of payload on the weight plate. That leaves room for water, gear and passengers without going over the legal limit.
Is surface rust on a van a dealbreaker?
No. Surface rust on panels is normal and fixable in an afternoon. Structural rust on the chassis rails, suspension mounts or load-bearing sills is the real dealbreaker, because a proper repair often costs more than a first van is worth.
What mileage is too high for a conversion van?
On a diesel, service history matters more than mileage. A van with 250,000 km and full paperwork, including a recent timing belt, can be a safer buy than a 120,000 km van with no history at all.
Which vans are best for a first conversion?
The common panel vans: Peugeot Boxer, Citroen Relay, Fiat Ducato, Mercedes Sprinter, VW Crafter, Ford Transit and Renault Master. Their payload data, parts and conversion measurements are all easy to find, which makes planning simpler.
Should I get a van inspected before I buy it?
For an older diesel or a high-value van, yes. An independent pre-purchase inspection costs far less than a hidden engine or gearbox repair, and a seller who refuses one is telling you something.
Does it matter if the van has a timing belt or a timing chain?
Yes. A timing belt needs replacing at set intervals and a snapped one can wreck the engine. Ask when it was last changed and get proof, or budget to do it straight away.
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