STAGE 2 - ENGINE SHUTDOWN
The piston remains in this position as long as there is full oil pressure in the engine. The instant the engine is stopped, the oil pressure drops and the piston is driven forward by the pressure of the spring. Oil is forced into the turbocharger bearings at 20 psi (1.4 bar) for approximately 3 minutes while the hot turbocharger rotor is spinning; the piston continues to move forward until it reaches.the end of the piston rod.
The oil supplied from the accumulator, lubricates and cools the bearings and rotor.