COMMON T4
RUST AREAS.

Why T4s Rust

Age, trapped moisture, road salt, stone chips, blocked drainage and previous repairs all play a part. Heritage Parts Centre notes that corrosion is particularly likely around seams, panel joins and places where moisture can remain trapped, including the windscreen area.

The important distinction is between surface corrosion that can be dealt with early and corrosion that has spread into structural or hard-to-access metalwork.

Windscreen & Scuttle

The lower windscreen/scuttle area is one of the best-known T4 corrosion points. Moisture can sit around the screen seal and damaged paint can develop into bubbling, holes and water ingress.

• Look along the lower edge and corners of the windscreen.
• Check for bubbling paint, staining or previous repairs.
• Look inside for damp around the dashboard/A-pillar area.
• If the screen has been replaced, inspect the quality of the surrounding paintwork.

Wheel Arches & Wings

Wheel arches live in the firing line for water, salt and road debris. Inspect the lip of each arch, the inner arch where visible and the joins into neighbouring panels.

• Front wing edges and arch lips.
• Rear arches and quarter-panel seams.
• Inner wheel housings where accessible.
• Areas where mud or debris can sit behind trim or liners.

Fresh paint around one arch is not necessarily suspicious, but ask what was repaired and whether photographs of the work exist.

Sills, Jacking Points & Outriggers

The lower body deserves proper inspection rather than a glance from standing height. Heritage’s T4 repair-panel range includes sills, jacking points, chassis outriggers and floor sections because these areas can require genuine structural repair.

• Outer sill condition along both sides.
• Inner sill areas where visible.
• Jacking points and nearby seams.
• Chassis outriggers and crossmembers.
• Signs of crushed, plated or heavily undersealed repairs.

Sliding Door & Lower Rail

The bottom of the sliding door can corrode inside and out, while the lower track area is exposed to dirt and moisture. Heritage also recommends checking the door for play because worn running gear can affect how it sits and closes.

• Inspect the lower inner seam of the door.
• Check the outer skin for bubbling.
• Clean and inspect the lower running rail.
• Open and close the door several times and check for excessive vertical movement.

Fuel Filler Area

The metal around the fuel-filler flap and adjoining seams is another recognised T4 corrosion area.

• Open the flap and inspect the aperture closely.
• Check the surrounding outer panel for bubbling.
• Look behind accessible trim for staining or previous repairs.
• Check seams leading into the rear quarter panel.

Rear Crossmember & Spring Areas

Heritage specifically highlights corrosion around the rear crossmember above the rear springs. This is more important than a cosmetic door-edge bubble because it is part of the van’s underlying structure.

• Inspect the rear crossmember.
• Look around rear spring-seat areas.
• Check for heavy scaling, perforation or patch repairs.
• Use the MOT history to look for repeated corrosion advisories in the rear structure.

Floor, Chassis & Hidden Areas

The underside can look acceptable from one angle while corrosion is developing around seams, floor edges or previous repairs.

• Floor pan and load-area floor from above and below where possible.
• Main chassis rails.
• Inner wings.
• Crossmembers and outriggers.
• Mounting points and welded repairs.

Cab Doors, Tailgate & Rear Doors

Door bottoms and folded seams can retain moisture. Open every door and inspect both the visible outer skin and the lower inner edge.

• Cab door bottoms and corners.
• Tailgate lower seam or rear-door bottoms.
• Around window apertures and seals.
• Hinges, catches and drain areas.

Signs of Previous Repair

• Different paint texture or colour.
• Overspray on seals, trim or underside components.
• Uneven panel gaps.
• Heavy filler detectable by poor contours or cracking.
• Patch plates over old corrosion.
• Very fresh seam sealer or underbody coating in one isolated area.

A repaired van can be an excellent van. What matters is whether the corrosion was cut out and repaired properly rather than disguised until the next owner becomes involved.

Keeping Corrosion Under Control

• Keep drains, seams and lower tracks clear of dirt.
• Repair stone chips and damaged paint before corrosion spreads.
• Wash salt and mud from the underside, especially after winter use.
• Inspect known T4 trouble spots at least periodically rather than waiting for the MOT.
• Use appropriate cavity protection/underbody products after sound repairs and preparation.

T4 Rust Inspection

• Windscreen/scuttle
• Front arches/wings
• Rear wheel arches
• Outer and inner sills
• Jacking points/outriggers
• Sliding door bottom/rail
• Fuel-filler area
• Rear crossmember/spring areas
• Floor and chassis
• Door/tailgate bottoms
• Previous weld repairs
• Fresh underseal investigated