Gilly:
Thanks for the quick response. I purchased my ML in June of 03 when it had 35,000 miles on it. It now has 45,800 miles. It had 1 year left on the original factory warranty, then a 1 year or 50,000 mile Starmark! When I took it in to my dealer recently for the A service and a bad MAF sensor they did the P/S hose upgrade for me, as I had pointed out it had a slight leak, so I doubt they did the filter upgrade before they Starmarked it! I have a good relationship with my dealer's service department, and they have told me they would fix this under my warranty. I believe the regulator is integral to the pump, correct? I just wanted as much information as I could before I took it in so I could understand the problem. I was a line mechanic for GM early in my career, and then 37 years as a machininst for Boeing, and in my experience when the sound of any machine changes, there is something wrong!! Thanks for your input!

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David L