1990 Ford Escort 1.6L Petrol · H401 AEE

The battery mounting tray in the engine compartment sits directly above the passenger-side bulkhead above the interior Central Electronic Module (main fusebox). Acid spills from aging lead-acid batteries and blocked scuttle drain grommets cause the thin sheet metal of the battery tray and surrounding seam sealer to corrode and perforate. Rainwater washes through the rust hole directly onto the internal multi-layer printed circuit board of the fusebox, causing copper track corrosion, dry solder joints, and chaotic electrical malfunctions across multiple circuits.

The rear inner and outer quarter panels on Mk5 and Mk6 Escorts feature an unsealed cavity surrounding the fuel filler pipe neck. Road spray, mud, and road salt thrown up by the rear offside tyre accumulate in the ledge behind the fuel flap rubber seal. Lacking modern plastic wheel arch liners and robust factory galvanising, the steel panels corrode rapidly from the inside out, bubbling through the exterior paintwork around the fuel cap and spreading into the rear arch lips, inner wheel tub, and rear chassis legs.