What goes wrong, what it costs, and what to check before you buy a used MG B GT.
The MG B GT occupies a niche position on the UK market.
We track 5 known issues across the MG B GT range, including 1 rated as safety-critical. Knowing which variants and configurations to approach with caution can save you from expensive surprises after purchase.
Found a MG B GT? Enter the reg to see which of our 5 known issues apply to that exact car, plus full MOT history and mileage checks.
MkI (1965–1974) — Engine options included the B-Series 1.8. Our database flags 5 known issues on this generation, 1 of which are rated as safety-critical. The most significant concern is Structural corrosion compromising vehicle rigidity (£500–£8,000 to address).
MkII (1974–1980) — Engine options included the B-Series 1.8. Our database flags 5 known issues on this generation, 1 of which are rated as safety-critical. The most significant concern is Structural corrosion compromising vehicle rigidity (£500–£8,000 to address).
The MG B GT uses a monocoque steel construction without a separate chassis, making structural corrosion particularly serious. The most critical areas are the A-posts, door frames, sills, and rear suspension mounting points where corrosion can compromise the structural integrity of the entire vehicle. This is a documented characteristic of 1960s-1970s British steel construction with minimal rust protection. MOT data shows this model fails structural rigidity tests at 34 times the fleet average, with failures becoming more frequent over the monitoring period.
Structural corrosion can lead to catastrophic failure of the vehicle's load-bearing structure, particularly in an accident. The car becomes unsafe to drive and may fail its MOT. Repair costs vary enormously depending on extent but can exceed the vehicle's value, with full restoration involving cutting out and replacing entire sections.
Inspect the wheel arches, sills, jacking points and door bottoms carefully. Press gently on sills to check for soft spots. Look underneath for corrosion on structural components. Check the MOT history for corrosion-related advisories or failures.
Cars built before emissions regulations struggle to meet modern MOT emissions standards, particularly carbon monoxide and hydrocarbon limits. The MG B GT uses twin SU carburettors and a basic ignition system without catalytic converters or oxygen sensors. MOT data shows this model fails emissions tests at 264 times the fleet average, with the worst failures occurring between 60,000-80,000 miles. The failure rate has been worsening over the monitoring period as these cars age further.
The car will fail its annual MOT test and cannot be legally driven on public roads. Carburettor overhaul and ignition system attention typically resolve most emissions issues. Total cost including labour ranges from £200-800 depending on the extent of work required.
Check for any engine warning lights on the dashboard. Ask about the car's MOT emissions history — repeated failures suggest underlying issues. A pre-purchase diagnostic scan is especially worthwhile to check for stored emissions fault codes.
The MG B GT uses rubber bushes throughout its suspension system that deteriorate with age regardless of mileage. After 40-50 years, original rubber bushes become hard, crack, and allow excessive play in the suspension geometry. MOT data shows this model fails for excessive suspension wear at 127 times the fleet average. The problem affects trunnions, A-arm bushes, and anti-roll bar mountings, and is getting worse as the remaining car population ages.
Worn suspension bushes affect handling, steering precision, and tyre wear. The car will eventually fail its MOT test. Driving with severely worn bushes is unsafe as it compromises vehicle control. A full suspension bush replacement typically costs £300-800 depending on extent.
Listen for knocking, clunking or rattling over bumps during the test drive. Inspect the underside for corroded or cracked suspension components. Check the MOT history for suspension-related advisories, which often predict future failures.
Wire wheel MG B GTs use knock-on wheel hubs with taper roller bearings that require regular adjustment and maintenance. The bearings are exposed to road dirt and moisture through the splined wheel mounting system. MOT data shows this model fails for wheel bearing problems at 28 times the fleet average for excessive play, with additional failures for rough bearings. Neglected bearings can seize or collapse completely.
Failed wheel bearings can cause wheel wobble, steering vibration, and in extreme cases wheel detachment. The car will fail its MOT and is unsafe to drive with severely worn bearings. Bearing replacement typically costs £100-300 per corner including labour.
Listen for knocking, clunking or rattling over bumps during the test drive. Inspect the underside for corroded or cracked suspension components. Check the MOT history for suspension-related advisories, which often predict future failures.
The rubber gaiters that protect the steering rack ball joints from dirt and moisture deteriorate with age on these cars. MOT data shows failures for damaged or missing steering gaiters at 46-52 times the fleet average. While not immediately dangerous, failed gaiters allow dirt and water to enter the ball joints, leading to premature wear and eventual steering problems.
Failed gaiters lead to accelerated wear of steering rack ball joints. The car will fail its MOT test. Replacement gaiters cost £20-50 but if contamination has occurred, ball joint replacement adds £200-400 to the repair cost.
During the test drive, check the steering for excessive play, vibration or pulling to one side. Listen for groaning or whining when turning the wheel at low speed. Power steering fluid level and condition should be checked on hydraulic systems.
For the full breakdown of all 5 tracked issues with repair costs, see the MG B GT common problems page.
Based on 8k real DVSA MOT tests, the MG B GT fails more often than average on several items. The biggest outlier is emissions failure at 307x the fleet average, followed by transmission joint, belt or chain worn (139x).
When viewing a specific car, check its MOT history for recurring advisories in these categories. See the full MG B GT MOT failure breakdown for data at every mileage point.
Routine servicing (oil and filter change every 3k miles) typically costs £45–£75 at an independent garage.
See the full MG B GT service schedule for every interval and cost breakdown.
The MG B GT has some well-documented weak points, including 1 safety-critical issue that demand careful checking. The right example, properly maintained, can still be a sound purchase — but cutting corners on the pre-purchase inspection is not advisable.
Before committing, check the car's full MOT history, verify the service record is complete, and if possible arrange a specialist inspection. Enter any registration into our free report to see the complete picture.
Get Car Wise maintains a database of known mechanical issues for every popular car on UK roads, tracking the faults that owners, specialists and DVSA data reveal.
When you run a report on a specific MG B GT, we cross-reference the exact variant, engine and age against our database of 5 known issues. Combined with full MOT history analysis, mileage verification and DVLA data, you get a complete picture before viewing.
Enter the registration for MOT history, mileage verification, known faults for that exact variant, and a Get Car Wise Score.
This guide was compiled from independent expert reviews, DVSA MOT data, specialist workshops and our own database of 5 known MG B GT issues. We are not affiliated with any source listed.