The earliest Midgets, fitted with the 948cc and 1098cc A-Series engines, used a vertical-flow brass and copper radiator in which the top tank acts as both the coolant reservoir and the filler point. Identifying the correct radiator and hose set for these early cars is essential, as the vertical-flow layout differs entirely from the later crossflow arrangement of some 1275cc cars and cannot be interchanged.
Vertical-Flow Radiator
The vertical-flow radiator carries coolant from the top tank down through the core to the bottom tank, with the filler and pressure cap on the top tank. The radiator mounts on a cradle bolted to the front inner wing structure. The 948cc and 1098cc share this fundamental layout, with the radiator's cooling capacity suited to these smaller-capacity engines. A correct-pattern radiator preserves the original appearance and mounting.
Hoses and Bypass
The top hose runs from the thermostat housing to the radiator top tank, and the bottom hose from the radiator base to the water pump inlet. A bypass hose between the water pump and cylinder head maintains coolant circulation while the thermostat is closed, allowing the engine to warm evenly. The hoses are specific to this engine and radiator layout, so they must be matched to the early car.
Pressure Cap and Clips
The pressure cap raises the system's boiling point and must be of the correct rating for the system; an incorrect cap causes either coolant loss or over-pressurisation. Hose clips secure each connection and are renewed with the hoses, as corroded or worn clips are a common source of slow leaks.
Ordering Considerations
Confirm the engine is the 948cc or 1098cc and that the car retains the vertical-flow layout before ordering, as engine swaps and past repairs can mean a non-original cooling system is fitted. Order top, bottom, and bypass hoses with new clips together, as renewing the complete set is more reliable than replacing hoses piecemeal.