The MGB GT V8 radiator is a brass-and-copper cross-flow design, coolant enters at one side header tank and exits at the opposite side after passing horizontally through the matrix. This layout was selected to provide adequate frontal area within the V8's tight engine bay packaging while keeping the bonnet line standard, and is mounted further forward than on the four-cylinder car to clear the wider V8 engine. Two factory part numbers cover V8 production: ARC88E (reconditioned exchange) for chrome-bumper cars and NRP1059 (new) for rubber-bumper cars. The V8 radiator has no filler cap of its own, the system pressure cap sits on the separate expansion tank.
The V8 radiator is not interchangeable with any four-cylinder MGB radiator.
Expansion Tank and Pressure Cap
Because the V8 cooling system is semi-sealed, a separate metal expansion tank (ARH250) is mounted in the front left-hand corner of the engine bay and connected to the radiator by hose. The 15 lb/sq in pressure cap (GRC110) sits on the expansion tank. The pressure cap is a wear item and should be renewed periodically, as a cap that no longer holds its rated pressure will cause coolant boil-over at temperatures the system would otherwise handle. A later transparent plastic alternative tank (AEH259) is available where being able to see the coolant level easily is preferred.
Coolant Hoses
Top hose (GRH512), bottom hose (GRH511), by-pass hose (GZA1894), steam hose (BHH1064), the overflow and tank-to-radiator hoses (GRH1001M, GRH1005M) and the heater hoses are all V8-specific and routed to suit the cross-flow radiator and V8 engine layout. The top hose runs from the thermostat housing on the engine to the radiator inlet; the bottom hose runs from the radiator outlet to the water pump inlet; the by-pass hose provides coolant circulation through the engine while the thermostat is closed during warm-up. Heater hoses run from the engine to the heater matrix and back, with heater valve and tap connections at the engine end.
Hose Kit and Hose Clips
The CHK8 cooling and heating hose kit provides all radiator hoses, heater hoses, by-pass hose and steam hose plus all clips necessary to fit, a cost-effective way to renew the entire system in one operation. Original-pattern wire and worm-drive hose clips are available alongside modern stainless-steel constant-tension clips that maintain seal as the hose ages. Hose connections are a common source of coolant loss and should be checked during any cooling-system service.
MGOC Spares
MGOC Spares supplies V8-specific cross-flow radiators, the ARH250 expansion tank, the GRC110 15 lb pressure cap, all individual cooling hoses, the CHK8 hose kit and hose clips for the MGB GT V8.