The MGC uses specific top and bottom radiator hoses that are unique to the model and not interchangeable with MGB hoses of any era. The routing and profile of these hoses reflect the MGC's forward-mounted radiator position, the radiator sits further forward than on the MGB to accommodate the longer six-cylinder engine, and the different thermostat housing location on the C-series cylinder head. The top hose connects the thermostat housing outlet to the radiator header tank inlet, carrying hot coolant from the engine to the radiator for cooling. The bottom hose connects the radiator bottom tank to the water pump inlet, returning cooled coolant to the engine for recirculation.
Both hoses are moulded to specific profiles that accommodate the angles and distances between their connection points, a straight hose cut to length cannot be substituted, as it would kink at the bends and restrict coolant flow. Both hoses should be replaced as a pair during any cooling system overhaul, as a perished or softened hose on one side places increased strain on the remaining hose and introduces the risk of failure at the worst possible moment.
Bypass Hose
A bypass hose connects the water pump bypass adaptor to the thermostat housing, providing a coolant circulation path through the engine block while the thermostat is closed during warm-up. Without this circuit, hot spots can develop in the cylinder head while the rest of the engine remains cold, and the thermostat will not see circulating coolant to open at the correct point. The bypass also feeds the heater during warm-up, since the heater circuit relies on water pump flow that depends on this loop. Two clips secure each end.
The hose is often overlooked because it sits partially hidden behind the water pump and alternator, but its failure sprays coolant directly onto the alternator and fan belt, risking secondary electrical and belt damage on top of the coolant loss. Inspect by feel at every service for softening, swelling, or hardening.
Heater and Expansion Tank Hoses
Heater outlet hose and expansion tank hose are both sold by the metre, allowing the correct length to be cut for each installation. The heater hose connects the water pump heater adaptor to the heater valve and then to the heater matrix inside the car, its routing and length differ from the MGB owing to the different engine bay layout and the MGC-specific heater water valve position. The heater hose is a narrower bore than the radiator hoses and carries a lower volume of coolant, but its failure still causes coolant loss from the pressurised system. The expansion tank hose connects the radiator filler inlet to the expansion tank mounted on the front left-hand side of the engine bay, maintaining the semi-sealed system's ability to accommodate coolant expansion and contraction with temperature changes.
This hose must be in sound condition for the semi-sealed system to function correctly, a split or perished expansion tank hose allows coolant to leak during the expansion phase rather than flowing into the expansion tank, causing a gradual drop in coolant level that may not be noticed until the engine overheats.
Hose Clip Options
Two types of hose clip are available throughout the MGC cooling system: the original-style Supergrip wire clip, which provides an authentic period appearance for concours restoration, and the modern worm-drive jubilee clip, which offers easier adjustment and a more reliable clamping force for regular road use. Either type may be used at any connection point, the choice is one of preference and intended use. Supergrip clips are the correct original fitment and look right in a period-correct engine bay, but they require a specific tool to tighten and are more difficult to adjust once fitted. Jubilee clips can be adjusted with a simple screwdriver and provide a more evenly distributed clamping force around the hose circumference.
Four clips are required for the radiator hoses (two per hose), two for the bypass hose, and additional clips for the heater hose and expansion tank hose. When rebuilding the cooling system, replacing all hose clips at the same time as the hoses ensures every connection is secure and eliminates the common problem of old clips that have lost their spring tension or corroded at the adjustment mechanism.