The heater plumbing on the MGB GT V8 carries hot coolant from the engine to the heater matrix and back. Two hoses provide the supply and return, typically the supply hose connects to a take-off on the engine block or cylinder head area, runs to the heater valve mounted on the engine, then to the heater matrix; the return hose runs from the matrix back to a return point on the engine. Hose routings are V8-specific and dictated by the V8 engine's layout.
V8-Specific Heater Valve
The V8 heater valve is V8-specific and operates in the opposite direction to the MGB 1800 heater valve. Pulling the dashboard heater control to one extreme opens the valve fully (maximum heat); pulling it to the other extreme closes the valve fully (no heat). The V8 valve's opposite operation reflects the cable routing in the V8 fascia layout. The valve is mounted on the engine and connects to the dashboard control via a Bowden cable.
Heater Controls
The heater controls on the dashboard comprise the temperature control (operating the heater valve via cable), the fan speed switch (multi-position rotary or rocker switch), and the air distribution control (operating internal flaps in the heater box via cable or linkage). The controls are V8 fascia-specific in their mounting and appearance, matched to the V8 fascia panel HZA4916E layout.
Service Notes
Heater valve service typically requires either valve replacement or rebuild kit fitting. Stuck valves are common, the valve interior corrodes from years of coolant contact and the valve plug binds in its bore. Cable adjustment may be needed to ensure the valve operates over its full range from the dashboard control. Heater hose renewal during major engine work is good practice.
MGOC Spares
MGOC Spares supplies V8-specific heater valves, heater hoses, heater control cables and heater control components for the MGB GT V8.