Question 1

Sill Corrosion (Inner and Outer)

Accepted Answer

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. 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. 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.

Question 2

Floor Pan Corrosion

Accepted Answer

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. Water enters through deteriorated door seals, windscreen seals, and from below via road spray. Carpet retains moisture against the metal. The floor pans are thin and have minimal factory corrosion protection. Repair sections are available for all floor areas. Weld in new metal. Cost: $500--1,500 per section depending on extent.

Question 3

A-Post Corrosion

Accepted Answer

Rust at the base of the windscreen pillars where they meet the scuttle panel. This area can be invisible until advanced. Water runs down the windscreen surround and collects at the base of the A-post. The double-skinned construction traps moisture. Cut out and fabricate new sections. This is skilled work that requires correct jigging. Cost: $1,500--3,000 for professional repair.

Question 4

Door Skin Corrosion

Accepted Answer

Rust along the bottom edge of each door, working upward from the inside. Drain holes in the door bottoms block, trapping water inside the door shell. The steel corrodes from inside out. Replacement door skins are available. The skin is peeled off the frame, the frame is treated, and a new skin is crimped on. Cost: $300--600 per door.

Question 5

Boot Floor and Battery Box Corrosion

Accepted Answer

The boot floor softens and perforates, particularly around the battery box (in cars with the twin 6-volt battery setup in the boot). Acid weeps from the batteries and eats through the floor pan. Battery acid is highly corrosive and the factory didn't provide adequate protection. Even with a sealed battery, condensation and minor spills accumulate. Road spray attacks the underside simultaneously. New boot floor repair sections and battery box panels are available. Clean back to solid metal, treat, and weld in new panels. Fit a fibreglass battery tray or line the area with acid-resistant paint after repair. Cost: $300--800 depending on extent.

Question 6

Rear Spring Hanger Corrosion

Accepted Answer

The mounting points for the leaf spring rear suspension corrode, crack, or tear away from the body. Road spray and mud accumulate around the spring hangers. The metal thins and weakens under the constant load of the spring. New spring hanger assemblies are available. Weld in replacements. Cost: $300--800 per side.

Question 7

Bottom End Bearing Wear

Accepted Answer

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. 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. 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.

Question 8

Overheating

Accepted Answer

Temperature gauge climbs into the red, particularly in traffic or on hot days. Coolant loss through the overflow. The MGB's cooling system is marginal for Australian conditions. The original radiator loses efficiency with age. The thermostat sticks. The water pump impeller corrodes. The electric fan (rubber bumper cars) or mechanical fan (chrome bumper cars) may not move enough air at low speeds. Replace the radiator with an aluminium upgrade ($300--500). New thermostat ($15--30), new water pump ($60--100), and ensure the fan system works properly. A supplementary electric fan is a sensible upgrade for chrome bumper cars. Check the coolant expansion tank (later cars) is functioning correctly -- the system relies on drawing coolant back from the tank as it cools, and a faulty pressure cap or cracked tank breaks this cycle. Total cooling system refresh: $300--700.

Question 9

Oil Leaks

Accepted Answer

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

Question 10

Cylinder Head Cracking

Accepted Answer

Coolant consumption with no visible external leak. Milky residue on the oil filler cap. White smoke from the exhaust. Overheating. The B-series head can crack between the valve seats, particularly on engines that have been overheated. The head is cast iron and can be repaired, but prevention (maintaining the cooling system) is far better than cure. Remove the head, check for cracks (pressure test), and either repair or replace. Remanufactured heads are available. Cost: $800--1,500 for head replacement including gasket and machining.

Question 11

Exhaust Manifold Studs and Cracking

Accepted Answer

Exhaust manifold studs corrode and snap when you try to remove them. The manifold itself can crack between the ports, causing a ticking exhaust leak that's louder when cold. The manifold operates through extreme thermal cycles -- red hot under load, cold overnight. The cast iron fatigues over decades. The studs corrode in the block because the dissimilar metals (steel stud in aluminium or iron block) create a galvanic cell, particularly in the presence of exhaust moisture. Snapped studs need careful extraction -- drilling and using an easy-out, or welding a nut onto the stud remains. A cracked manifold can sometimes be welded by a specialist, but replacement is usually more practical. Aftermarket tubular manifolds ($200--400) improve flow and eliminate the cracking issue entirely. Apply copper anti-seize to all new manifold studs.

Question 12

Second Gear Synchro Wear

Accepted Answer

A crunch or grind when shifting quickly from 3rd to 2nd gear, especially when the engine is cold. Second gear takes the most punishment in normal driving -- it's the gear you downshift to most often. The brass synchro ring wears thin and can no longer match shaft speeds effectively. Gearbox rebuild with new synchro rings. Cost: $800--1,500 for a rebuild. A used replacement gearbox from a specialist is $400--800.

Question 13

Overdrive Failure

Accepted Answer

The overdrive fails to engage, engages intermittently, or drops out under load. The Laycock overdrive is an electro-hydraulic unit. Common failures include a faulty solenoid ($80--150), worn wiring or switch ($20--50), low oil level in the gearbox (the overdrive shares gearbox oil), or worn internal components (clutch plates, pistons). Start with the simple items: check the wiring, switch, and oil level. If the solenoid clicks but the overdrive doesn't engage, the internal hydraulics need attention. A full overdrive rebuild: $600--1,200.

Question 14

Brake Master Cylinder Failure

Accepted Answer

A spongy brake pedal that sinks to the floor under sustained pressure. Brake fluid weeping from the master cylinder body or around the pushrod seal. Air in the system despite repeated bleeding. The internal seals in the master cylinder harden with age and allow fluid to bypass. On later dual-circuit cars (1975 onwards), the tandem master cylinder has twice as many seals to fail. Brake fluid absorbs moisture over time, which corrodes the cylinder bore from within. Rebuild kits are available ($30--50) but a new or remanufactured master cylinder ($80--150) is more reliable. Flush the entire brake system with fresh DOT 4 fluid every two years -- this single maintenance item prevents most master cylinder failures.

Question 15

Brake Servo Failure (Later Cars)

Accepted Answer

Hard brake pedal with dramatically reduced braking assistance. In the worst cases, reported by MGB Register members, fluid can leak internally into the servo canister -- the pedal feels normal until you press it, then all the fluid disappears into the servo and you have no brakes at all. The servo diaphragm deteriorates with age and heat. The vacuum hose perishes. On rubber bumper cars, the servo is mounted in the engine bay between the pedal box and master cylinder, exposed to significant heat. Replace the servo unit ($150--300). Check the vacuum hose and one-way valve. If the servo has failed catastrophically (fluid leaking internally), the car must be towed, not driven.

Question 16

Seized Rear Brake Cylinders

Accepted Answer

One rear wheel locks or drags. The car pulls to one side under braking. A burning smell from one rear wheel after driving. The rear wheel cylinders corrode internally. The pistons seize in the bore, either stuck extended (dragging brake) or stuck retracted (no braking on that wheel). Cars that sit for long periods are particularly susceptible. Replace both rear wheel cylinders as a pair ($30--60 each). Inspect the drums for scoring. Cost: $100--250 for both sides including shoes if needed.

Question 17

Clutch Hydraulic Failure

Accepted Answer

The clutch pedal drops to the floor with no resistance. No clutch disengagement -- the car won't go into gear with the engine running. Fluid visible on the carpet (master cylinder leak) or on the bellhousing (slave cylinder leak). The clutch master cylinder and slave cylinder use rubber seals that harden and fail with age, identical to the brake system. The copper hydraulic line between them also corrodes, particularly at the flare fittings. Forum members report that aftermarket slave cylinders with a flexible hose (rather than rigid pipe runs) make bleeding significantly easier. Replace the master cylinder ($40--80), slave cylinder ($30--60), and the connecting pipe. Bleed the system. Tip from experienced owners: when bleeding, remove the slave cylinder from its mount and hold it higher than the master cylinder -- air bubbles rise, making the bleed much quicker. Cost: $80--180 for all new components.

Question 18

Lucas Alternator and Charging Failures

Accepted Answer

Dim lights, slow cranking, dead battery, charging light on the dashboard. The Lucas alternator's brushes wear, the voltage regulator fails, and the bearings give out. On early cars with generators, the commutator wears and the brushes make poor contact. Rebuild or replace the alternator. A modern replacement alternator ($100--200) is a practical upgrade. Ensure all earth connections are clean and tight -- poor earths cause more electrical problems on MGBs than component failures.

Question 19

Earth (Ground) Connection Corrosion

Accepted Answer

Intermittent electrical failures, dim lights on one side, instruments reading incorrectly, indicators flashing at wrong speed. The MGB relies on the body as the earth return path. Corrosion at earth strap connections -- engine to body, body to frame, battery earth -- creates resistance in the circuit. This is the single most common cause of electrical problems on the MGB. Clean every earth connection to bright metal, apply dielectric grease, and retighten. Add supplementary earth straps if necessary. Cost: $0--30.

Question 20

Ignition Component Failure

Accepted Answer

Sudden engine death, misfiring, no-start condition. The points-type ignition system relies on a condenser, contact breaker points, rotor arm, and distributor cap -- all of which wear and fail. The condenser is the most common sudden-failure item. Modern aftermarket condensers are often poor quality. Carry spares. Alternatively, fit an electronic ignition conversion (Pertronix, Powerspark, or Accuspark -- $80--150) that eliminates the points and condenser entirely. This is one of the best upgrades you can make to any MGB.

Question 21

Front Kingpin Wear (Chrome Bumper Cars)

Accepted Answer

Clunking from the front end, wandering on straight roads, uneven tyre wear. Chrome bumper MGBs use kingpins rather than ball joints for the front upright. The kingpin bushings wear, introducing play. The grease nipples must be serviced regularly -- many owners forget. Replace the kingpin bushings and thrust washers. The kingpins themselves are usually reusable. Cost: $200--400 per side including parts and labour.

Question 22

Leaf Spring Fatigue

Accepted Answer

Rear of the car sits low. Sagging stance. Poor ride quality and reduced handling. The leaf springs lose their temper (metallurgical, not emotional) over decades. Overloading and fatigue cycling flatten the springs. Replace with new leaf springs. Parabolic spring conversions are available and offer significantly improved ride quality. Cost: $300--600 per set for standard, $500--800 for parabolic.

Question 23

Fuel Pump Failure

Accepted Answer

Engine starves for fuel under load, particularly at high RPM or when the tank is low. The engine sputters and dies, then restarts after a few minutes (vapour lock). The SU electric fuel pump (mounted at the rear near the tank) uses contact points that corrode and pit. Modern ethanol-blended fuel accelerates deterioration of the pump's internal diaphragm. Rebuild the pump ($40--80 for a kit) or replace with a modern solid-state fuel pump ($80--150). The electronic replacements are more reliable and quieter.

Question 24

Carburettor Wear and Maladjustment

Accepted Answer

Rough idle, hesitation, poor fuel economy, rich or lean running. The twin SU carburettors (chrome bumper) or single Zenith-Stromberg (rubber bumper) have numerous wear points. SU throttle shaft bushings develop play (causing air leaks), needles and jets wear, damper oil level drops, and the mixture drifts with age. SU carburettors respond beautifully to a proper service. New needles and jets ($30--50 per carb), new bushings if worn ($50--100 per carb), correct damper oil level, and careful mixture adjustment. A well-set-up pair of SUs is a thing of beauty. Cost: $80--200 DIY for a full service kit.

Question 25

Door Seal and Window Seal Gaps

Accepted Answer

Wind noise, water leaks at speed, and a gap visible between the top of the door window and the door frame seal. The door may require slamming to close. Replacement rubber seals are often a slightly different profile to the originals -- harder rubber, marginally different dimensions. The door glass alignment shifts as hinges wear. Forum members consistently report that new seals from most suppliers don't sit quite right out of the box. Adjust the door catch striker plate on the B-pillar to pull the door tighter. Adjust the window glass position (the window channel bolts allow fore/aft and in/out adjustment). Some owners warm the rubber with a heat gun to help it conform. New seals do settle over time. If the seal profile is genuinely wrong, try a different supplier.

Question 26

Hood (Soft Top) Deterioration

Accepted Answer

The hood fabric shrinks and becomes difficult to erect. The rear window (plastic on most cars) turns opaque and cracks. Water pools on the roof and finds its way through stitch holes and seams. UV exposure degrades both the fabric and plastic window. The PVC or mohair shrinks with age and heat cycling. The frame itself can distort, putting tension in the wrong places. A new hood ($300--600 for PVC, $500--900 for mohair). Fitting requires care -- the hood is glued, stapled, and screwed to the frame and body. Professional fitting is recommended unless you have experience. A glass rear window conversion eliminates the fogging plastic.

Question 27

Windscreen Pillar Seal Leaks

Accepted Answer

Water drips onto the dashboard or down the A-posts during rain or car washing. The windscreen surround seal hardens, shrinks, and loses its sealing contact. On chrome bumper cars, the windscreen is held by a chrome surround that relies on a rubber gasket. On rubber bumper cars, the screen is bonded. Refit or replace the windscreen seal. On chrome bumper cars, the screen must be removed, the channel cleaned, a new seal fitted, and the screen reinstalled -- a fiddly but straightforward job. Cost: $40--80 for the seal, $100--200 for professional fitting.

MGB Roadster

MGB Roadster known problems