The MGB GT V8 uses a closed-circuit crankcase breather system. Crankcase blow-by gases, combustion products that escape past the piston rings into the crankcase during the power stroke, are vented from the rocker covers via flexible hoses to a take-off on the inlet manifold area, where they are drawn into the engine and burned alongside the fresh fuel-air charge. The arrangement prevents pressurisation of the crankcase, which would otherwise force oil leaks at every gasket and seal, and reduces emissions of unburned hydrocarbons.
Breather Components
The breather hoses, T-pieces, sealing components and inlet manifold connection are all V8-specific items. The rocker cover end of each hose connects to a fitting on the cover; the inlet manifold end connects to a take-off carrying the gases into the engine's induction system. Hoses age and harden in the heat of the engine bay and should be inspected during routine service.
System Faults
A blocked or restricted breather system causes crankcase pressurisation, with symptoms including oil leaks at gaskets and seals, oil mist in the air filter housing and sometimes a smell of oil in the cabin. A disconnected breather causes the same problems in addition to releasing crankcase fumes into the engine bay. Both conditions warrant immediate inspection of the breather hoses and connections.
MGOC Spares
MGOC Spares supplies breather hoses, T-pieces, sealing components and connection fittings for the MGB GT V8 crankcase ventilation system.