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MOTRS

MGB Roadster

1962-1980 / Roadster / United Kingdom

All MGB Roadster problems All workshop issues
Minor Body and Structure

Sill Corrosion (Inner and Outer)

Symptoms

The outer sill skin bubbles, softens, and eventually perforates. In advanced cases, the outer sill crumbles when prodded. The inner sill -- the structural member -- rots from inside the box section and loses its load-bearing capacity.

Cause

The sills are box-section steel with drain holes at the bottom. These holes block with dirt and underseal, trapping water inside the cavity. Corrosion works from inside out, so by the time you see exterior rust, the inner sill may be compromised. The sills are structural -- they carry bending loads and support the door hinges.

Fix

Replace both inner and outer sill sections.

This requires stripping the car to bare metal in the sill area, cutting out the corroded metal, and welding new panels.

Quality repair panels are readily available from Moss Motors, British Motor Heritage, and others.

Cost: $1,500--3,000 per side for professional work.

DIY is possible but requires competent welding skills.

Cost mentioned in fix
Cost: $1,500

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Other known issues

Critical Body and Structure

Floor Pan Corrosion

Soft or perforated floor pans, particularly in the footwells and under the seats. Wet carpet is a telltale sign. In severe cases, you can see the road through the floor.
Minor Body and Structure

A-Post Corrosion

Rust at the base of the windscreen pillars where they meet the scuttle panel. This area can be invisible until advanced.
Minor Body and Structure

Door Skin Corrosion

Rust along the bottom edge of each door, working upward from the inside.
Minor Body and Structure

Rear Spring Hanger Corrosion

The mounting points for the leaf spring rear suspension corrode, crack, or tear away from the body.
Critical Engine

Bottom End Bearing Wear

Low oil pressure at idle when warm (below 15 psi). A deep rumbling or knocking sound from the lower engine, particularly at idle and on acceleration. This is the main and big-end bearings wearing out.
Minor Engine

Overheating

Temperature gauge climbs into the red, particularly in traffic or on hot days. Coolant loss through the overflow.
View all 18 MGB Roadster problems