Abstract: A vertically oriented hydrocleaning machine comprising a motor having a housing and a downwardly oriented vertical drive shaft, and an axial pump having a piston guide unit driven by the drive shaft. The motor housing includes a closure lid which defines a shaft support for the motor drive shaft, an annular bearing seat, and at least one reference surface for facilitating concentric aligned mounting of the piston guide on the motor, without the necessity for an intermediate mounting flange between the piston guide unit and motor. The illustrated motor closure lid further defines an oil sump chamber internally within the motor and a further annular seat within which a shaft sealing ring is disposed. The motor housing closure lid enables the piston guide unit to be quickly and precisely secured to the drive motor to produce a more compact and rigid high pressure washer.