The MGB cooling system was designed for the driving conditions and traffic densities of the 1960s and 1970s, and while it is fundamentally sound, there are areas where modern materials and aftermarket upgrades can improve cooling efficiency, reliability, and convenience, particularly on modified engines, cars used in warmer climates, or vehicles that spend time in congested modern traffic. Aluminium radiators are available for all three MGB cooling system configurations, the rear-fill radiator on 3-synchro cars, the centre-fill radiator on 4-synchro cars up to September 1976, and the forward-mounted electric fan radiator from September 1976 onwards. Aluminium offers greater cooling efficiency than the original copper and brass construction, allowing engines to run at lower temperatures under equivalent conditions. This is particularly beneficial on cars with performance modifications that increase heat output, or on cars used for track days and spirited driving where the standard radiator may struggle to maintain safe operating temperatures.
Electric Fan Conversions
Electric fan conversion kits offer one of the most effective cooling upgrades for pre-September 1976 cars that originally used a mechanical engine-driven fan. An aftermarket electric fan operates thermostatically, cutting in only when the coolant reaches a set temperature, and offers several advantages over the belt-driven arrangement. It eliminates the parasitic power drain of a permanently driven fan, allows the engine to warm up more quickly, reduces fan noise at cruising speed, and provides effective cooling even at idle in stationary traffic, where a mechanical fan spinning at low rpm delivers minimal airflow. A thermostatic switch kit is available separately for fitting into the top radiator hose, providing the temperature-sensing control for the fan independently of the radiator.
Hoses & Coolant Additives
Silicone cooling hoses offer a significant improvement in longevity and reliability over standard rubber. They resist hardening, cracking, and deterioration far more effectively, and are supplied with stainless steel band clips. Silicone hose sets are available for the 18V engine configuration from 1972 to September 1976, and are particularly well suited to cars that are regularly driven, stored for extended periods, or where the owner simply wants the reassurance of hoses that will not need replacing for many years. Kevlar-reinforced cooling hose kits are available for all three cooling system configurations and provide improved resistance to collapse and internal deterioration compared to standard rubber hoses, while retaining a standard appearance.
Cooling system additives can further improve thermal performance. Water wetter is a heat transfer agent that lowers engine temperature by improving the coolant’s ability to absorb and release heat, one bottle treats the full MGB cooling system. Long-life coolant provides ten years of corrosion protection, anti-freeze down to -42°C, and a built-in colour indicator that warns of head gasket failure.
For owners who want their engine up to temperature before starting, reducing cold-start wear, eliminating the need for choke, and providing instant cabin heat, an engine pre-heater is available. This uses a mains electricity supply to warm the coolant to normal operating temperature before the engine is started, and is suited to cars kept in a garage where a power supply is accessible. When upgrading any part of the cooling system, it is worth considering the system as a whole. A new aluminium radiator will deliver its best results when paired with fresh hoses, a correctly rated thermostat, a functional fan arrangement, and clean coolant.
MGOC Spares offers all the components needed to build a complete cooling system upgrade matched to any MGB configuration.