I have a 1999 ML 320. The power steering started to make a winding noise, it progessively got loader and loader. No leaks in the pump were noticable, no loss of fluid. It would wind excessively when turning the wheel so I concluded it had to be the pump. I replaced the pump and the noise seemed to have gone away but within few days of driving it has returned, although not quite as load. Any ideas what else this could be, I checked the serpintine belt and it shows no signs of where.
JP

Hopefully the problem wasn't the power steering pump. When the pump fails usually particles of metal get into the power steering fluid if you delay repairing it quickly, and then enter the power steering rack system. After that happens, you can change the pump but the metal particles will enter the new pump via the fluid and cause it to fail quickly. Sorry to say that unless the pump is replaced before metal particles start entering the fluid, you will have to replace both the pump and rack. Hopefully there is some other problem that is causing the the noise. Good luck!

Try replacing the reservoir..it has a built-in "filter" & they can cause noise..

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator