1999 Mercedes ML 430 Help!

[1highhog]

I own a 1999 ML 430 and have had several problems with it. It makes a popping noise when backing up or just driving really slow. I can't trace it down to any particular point on the car. Anyone else have this problem?

It also has another problem, I think it's coming from the power steering pump but when I check the fluid it's fine. It also turns as it should, not hard at all. I notice this when I'm sitting at a stop and needing to turn, it then whines. After reading some other forums on Mercedes, I was wondering if anyone knows of any recalls on this model 430. I'm not the orginal owner, and the vehicle now has 133,000 miles on it. Would Mercedes still fix any problems on my 430 if there is a recall? Any help would be appreciated.