MGB GT

1965-1980 / Coupe / United Kingdom

Critical Engine

Bottom End Bearing Wear

Symptoms

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.

Cause

Age and mileage. The B-series engine is tough but the white-metal bearings wear over 100,000+ km. Infrequent oil changes, overheating episodes, and oil starvation accelerate wear. The 3-main-bearing engines (1962--1964) are more susceptible.

Fix

Engine rebuild.

The crankshaft is reground to the next undersize, new bearings are fitted, and the engine is reassembled with new gaskets and seals.

Cost: $3,000--6,000 for a full rebuild.

Cost mentioned in fix

Cost: $3,000

Know something we don't?

Owned a MG MGB GT? Share your experience with this issue. What worked, what didn't, costs, tips. Help the community.

Submit an update

// More MGB GT problems

Other known issues

Minor Engine

Overheating

Temperature gauge climbs into the red, particularly in traffic or on hot days. Coolant loss through the overflow.

Critical Engine

Oil Leaks

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

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