Checking the tightness of the power steering system (Mercedes-Benz Sprinter 903)

Since fluid may occasionally leak from the system, a quick check will help determine the cause of the leak. The tightness test of the system must be carried out with an assistant as follows:

• the assistant should turn the steering wheel in both directions from lock to lock, briefly holding the steering wheel in the extreme positions. At the same time, maximum pressure is generated in the system, which allows the source of the leak to be determined;
• check the steering gear area from underneath the vehicle. After removing the covers from the steering gear side, check the connection points of the steering rods, the rack sealing rings, the power steering pump and the connection points of the hoses. Oil stains in these areas indicate a leak.

Information copied from the website mercedesman