When I purchased my truck the hydro-boost had a leak, but instead of replacing the gaskets I just purchased a whole new unit, (I figured after 205,000 miles I might as well). Now 2,500 miles later of no problems or leaks, I got in my truck yesterday morning, started it, and a couple seconds of idling later there was a loud noise coming from the hydro-boost. I quickly shut off my truck, waited a few minutes and then tried to start it up again, and it started doing it again. (P.S. whenever I tried turning the steering wheel or pressing the brake the sound would get louder). However I came home from work that evening and started it up and it didn’t make the sound, and drove just fine. And now today it did the exact same thing, in the morning before work it wasn’t working and then I got home and it worked (And yes brake and power steering fluid levels are fine) 

 

1999 Dodge Ram 2500 5.9 Cummins sport thanks in advance for any help provided!

Could be the power steering pump going out, this past winter it started wining when it was cold and it would make the brakes feel weird till it was warm. Replaced pump and all is good now. 
I thought mine was the hydroboost at first because of the weird brakes, even replaced it but still remained.