w126 560sel rear suspension problem

[rebel_mtc]

Hi guys my mechanic just replace the 2 accumulator air cells on the hydraulic suspension but the car would be bouncy at speeds of 120kph. like giving a free massage for the rear passenger ( the problem is intermitent)

Is there probably air trap within the lines? how do I bleed this out? The mechanic told me no bleeders for this system and it's self priming and air would go away after some time