Structural corrosion in floor pans, sills and inner wings
SeriousBodywork & RustWikipedia's Golf Mk3 article attributes the model's rarity today partly to quality issues with the steel Volkswagen used, which it reports led to significant corrosion in the floor pan, door sills and rear hatch, with independent mechanics and MOT testers advising buyers to inspect for rust, holes and patches in the floor pan. The UK Golf GTIforum buying guide reaches the same conclusion from the workshop end: sill rot where the rubber door seal meets the panel and at the front jacking points, floors rotting from the inside because the drain bungs let moisture in, and a driver's-side inner wing that looked clean under tidy underseal but had actually rotted through - a structural MOT failure.
Bubbling paint along the bottom of the doors and sill edge, Soft boot floor or a hole visible in the spare wheel well, Sump guard or jacking point flanges cracked by rust, Structure feels weak when the car is lifted at the jacking points
- Pry up the sill trim and look at the flange with a torch - RAC and the forum both say the trim hides the truth
- Press on the floor pan inside the boot with firm thumb pressure
- Check the inner wing and battery tray behind the wheel liner, and read the last two MOTs