Method for reducing oil leakage in a turbocharger

During engine braking of a turbocharged internal combustion engine, the exhaust gas pressure increases and this is used to pressurise the seals between the turbocharger shaft and the bearing housing so as to prevent oil leakage into the compressor housing. The diverted exhaust gas is stored in a plenum chamber and immediately after engine braking, the stored exhaust gas pressure is used to pressurise the seals at the turbine end so as to prevent oil leakage into the turbine housing.