MGB GT

1965-1980 / Coupe / United Kingdom

All MGB GT problems All workshop issues

Critical Engine

Oil Leaks

Symptoms

Oil residue on the engine, drips on the ground, burning smell from oil on the exhaust manifold.

Cause

Every gasket and seal on a B-series engine eventually leaks. The rocker cover gasket, timing cover gasket, rear main seal, oil pan gasket, distributor shaft seal, and tachometer drive seal are all culprits. The rear main seal is the most significant -- it's a rope-type seal that wears and cannot be properly replaced without engine or gearbox removal.

Fix

Systematic reseal.

Replace all gaskets and seals in one session.

Rocker cover gasket ($10--20), timing cover gasket ($15--30), sump gasket ($15--25), rear main seal (rope type: $20--40, requires gearbox removal).

Full reseal: $200--400 DIY, $600--1,200 at a workshop.

Cost mentioned in fix

$10$15$20$200$600

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// More MGB GT problems

Other known issues

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.

Critical Engine

Cylinder Head Cracking

Coolant consumption with no visible external leak. Milky residue on the oil filler cap. White smoke from the exhaust. Overheating.

Minor Body and Structure

Sill Corrosion (Inner and Outer)

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.

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.

View all 18 MGB GT problems