The MGC was fitted as standard with a six-blade yellow plastic fan, driven from the water pump pulley via a spacer. This fan is specific to the MGC and is not shared with the MGB, which used different fan types throughout its production. The fan is secured to the spacer by three screws, and the spacer to the water pump pulley by three further screws with spring washers. The yellow colour was a common feature of BMC cooling fans of the era, it served as a visual safety warning when working near the engine bay with the engine running.
The six-blade plastic design provides adequate cooling airflow for UK and most European driving conditions, generating sufficient draught through the radiator core at normal road speeds and during moderate urban driving. At sustained low idle speed, however, particularly in summer traffic, the mechanical fan's airflow drops significantly, and owners who regularly encounter these conditions may wish to consider an electric fan conversion for improved cooling under these specific circumstances.
North American Specification Fan
USA-market cars, and Canadian cars from 1968 onwards, were fitted with an eight-blade metal fan in place of the standard six-blade plastic unit. The metal fan uses different screws from the plastic fan for its attachment to the spacer, and the additional two blades generate a greater volume of air at low engine speeds than the home market fan, a necessary provision on North American specification cars which generate more heat from their emissions control equipment and may spend extended periods idling in heavy urban traffic. The eight-blade construction also produces noticeably more noise than the six-blade plastic fan, particularly at higher engine speeds where the metal blades create a distinctive whirring that is characteristic of North American MGCs.
When ordering a replacement fan, the market specification must be identified: home market (six-blade plastic) or North American (eight-blade metal). The two fans use different mounting screws and have different physical dimensions, they are not interchangeable.
Fan Belt
A single fan belt drives the water pump and alternator from the crankshaft pulley, making it one of the most critical ancillary components on the engine. The C-series engine's higher heat output compared to the MGB's four-cylinder unit makes consistent water pump flow and fan speed essential for maintaining safe operating temperatures. A fan belt that slips reduces both water pump flow and fan speed at precisely the moment when maximum cooling is needed, climbing a long hill on a warm day, for example, or sitting in traffic with the engine at full operating temperature. The belt should be inspected at every service for cracking across the inner surface, glazing on the contact faces that causes slipping, fraying at the edges, and correct tension.
Correct tension means approximately half an inch of deflection under firm thumb pressure at the midpoint between the crankshaft and water pump pulleys. Over-tightening is equally harmful, it overloads the water pump bearing and the alternator front bearing, shortening their service life. A spare fan belt should always be carried in the car's toolkit. Changing a fan belt at the roadside is a straightforward task that can prevent a breakdown from becoming a recovery, whereas a failed belt with no spare leaves the car stranded and the engine at immediate risk of overheating damage.
Electric Fan Conversion
For owners seeking improved cooling performance and reduced mechanical noise, two electric fan options are available. The Kenlowe electric fan kit replaces the existing mechanical fan blades and operates thermostatically, cutting in only when the coolant temperature requires it.
This allows the engine to warm up fully before the fan activates, increases available engine power by eliminating the parasitic drag of a permanently driven fan, and reduces mechanical fan noise, all worthwhile benefits for touring use. Revotec kits offer a similar thermostatically controlled solution with UK-manufactured model-specific brackets for direct fitment to the MGC radiator. A separate fan thermo-switch kit is available for fitting in the top hose, providing the temperature-sensing trigger for the electric fan activation. Both kits are covered in detail in their respective sections within Upgrades & Alternatives.