1964 model year · NHTSA recalls, manufacturer TSBs, and owner forum reports · Updated June 2026
According to Au7o's research across NHTSA recalls, manufacturer TSBs, and owner forum reports, the 1964 MG MGB has 3 documented known issues. No issues are rated critical, indicating generally reliable ownership. Across all issues, repair costs range from $150 to $2,500. DIY maintenance guides at au7o.io.
On the 1962-1964 MG MGB 1800 B-series I4 (3-bearing), early MGBs (1962 to early 1964) use the three-main-bearing 18G/18GA B-series. Its crankshaft has a flange at the rear that physically prevents fitting a modern lip seal, so the factory sealed the rear main with a 'reverse scroll' — a machined thread that pumps oil back toward the sump instead of an actual seal. It works only while the scroll and its mating surface are sharp. After decades the crank wears a faint groove and the scroll loses its pumping action, so a few drops always get past, drip out the bellhousing breather hole (which the factory drilled deliberately, knowing it would seep), and mark the driveway. It is not a catastrophic failure, but restorers chasing an oil-tight engine and a clean clutch are constantly frustrated by it.
Accept that a stock 3-main will always seep slightly and manage it: fresh scroll-area surface, correct end-float, a good rear scroll, and keep the bellhousing drain hole open so oil never backs up into the clutch. The proven bulletproofing route during a rebuild is to convert the rear of the crank to take a real lip seal — machine a seal journal/sleeve onto the crank flange and fit a modern lip-seal carrier (kits exist for this) — which finally makes the 3-main oil-tight. Many restorers instead swap to the later five-main-bearing crank/block, which uses a proper lip seal and is the simplest permanent cure. Always renew the front and side cover gaskets and the tappet-chest seals at the same time, as those mimic 'rear main' leaks.
On the 1962-1967 MG MGB 1800 B-series I4, the early MGB four-speed has synchromesh on only the top three gears (none on 1st) — the so-called 'three-synchro' box used through 1967. Its known weak points are the layshaft and its needle rollers (the original three-hole layshaft/laygear design is the fragile part) and the 2nd-gear synchro ring, which wears first and produces the classic crunch when shifting up into 2nd. Worn layshaft bearings give a rumble/whine in the gears and slop in the cluster. Left alone the synchros eventually let go and the box jumps or grinds.
On a rebuild, the community fix is to upgrade the internals rather than just replace like-for-like: fit the stronger larger 4-hole laygear (22H1301) with a quality layshaft and fresh needle rollers to cure the inherent layshaft weakness, renew the 2nd/3rd/4th synchro rings, and replace all bearings and seals. Done with the right parts, even a three-bearing-laygear box is good for 50,000+ miles. Many restorers go a step further and swap to the later all-synchro four-synchro box (1968-on) for everyday usability, and the most popular bulletproofing upgrade is adding a Laycock overdrive (or a modern 5-speed conversion) to drop cruising rpm and reduce strain. Drive sympathetically with a brief pause into 2nd to preserve the synchros.
On the 1962-1968 MG MGB 1800 B-series I4, early MGBs use a Lucas C40 dynamo (generator) with a separate external control box (voltage regulator), and the earliest cars are positive-earth. The dynamo only delivers around 12 amps after the regulator, which struggles to keep the battery charged at low rpm, in traffic, or with extra loads (driving lights, electric fan, modern stereo). The mechanical regulator points burn and drift out of adjustment, and the dynamo brushes/bushes wear, giving a dim-charge or no-charge condition. Combined with aged, undersized, deteriorated cloth-loom wiring and corroded earth straps, this is the source of the MGB's 'Prince of Darkness' reputation — flickering lights, slow cranking, and dead batteries.
The standard bulletproofing upgrade is to replace the dynamo with an alternator. Purists fit a 'Dynalite'/'Dynamator' — a modern 45-amp+ alternator hidden inside a dynamo case (available in positive- OR negative-earth, with or without tacho drive) so it bolts to the original mounts, reuses the original pulley, looks stock, and is reversible. The more thorough route is a full negative-earth conversion: fit a standard Lucas 16/17/18ACR-style alternator, convert the tachometer to negative earth, and delete the old control box. While in there, restorers renew the main wiring harness, upgrade earth straps (engine-to-body and body-to-battery), and clean every bullet connector — curing most 'random electrical gremlins' at once.
SERVICE BRAKES, HYDRAULIC:BRAKE FLUID LOW WARNING: LAMP
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According to Au7o's research across NHTSA recalls, manufacturer TSBs, and owner forum reports, the 1964-1964 MG MGB has 3 documented issues. The most frequently reported are: Three-Main-Bearing Rear 'Scroll Seal' Always Weeps Oil, Weak Three-Synchro Gearbox — 2nd-Gear Crunch and Layshaft Wear, Lucas Charging System — Weak Dynamo and Positive-Earth Wiring. None are rated critical, but regular maintenance is recommended.
The 1964-1964 MG MGB has 3 known issues compiled from NHTSA recalls, manufacturer TSBs, and owner forum reports. No issues are rated critical, suggesting generally good reliability. Regular maintenance following the manufacturer's schedule helps prevent many common problems.
Repair costs for known MG MGB issues range from $150 to $2,500, depending on the specific problem and whether you choose DIY or professional repair. Au7o provides step-by-step DIY maintenance guides that can help reduce repair costs.
Early MGBs (1962 to early 1964) use the three-main-bearing 18G/18GA B-series. Its crankshaft has a flange at the rear that physically prevents fitting a modern lip seal, so the factory sealed the rear main with a 'reverse scroll' — a machined thread that pumps oil back toward the… Repairs typically run $200-$1,800. Severity: medium.
The early MGB four-speed has synchromesh on only the top three gears (none on 1st) — the so-called 'three-synchro' box used through 1967. Its known weak points are the layshaft and its needle rollers (the original three-hole layshaft/laygear design is the fragile part) and the 2n… Repairs typically run $600-$2,500. Severity: medium.
Early MGBs use a Lucas C40 dynamo (generator) with a separate external control box (voltage regulator), and the earliest cars are positive-earth. The dynamo only delivers around 12 amps after the regulator, which struggles to keep the battery charged at low rpm, in traffic, or wi… Repairs typically run $150-$700. Severity: medium.
Content on this page was compiled with AI assistance using NHTSA complaints, TSBs, owner reports, and public automotive data. While we strive for accuracy, this information may contain errors. Always verify repair procedures and specifications with your vehicle's service manual or a qualified mechanic.
