So I just bought a 2007 RDX with 70,000 miles. The servicing documents were great the person who owned the car before myself doing normal flushes, oil changes ect. The day after I took it home I started hearing the famous hum from the PS pump that is well documented all over the internet. I have looked at many topics and dont know where to turn now seeing it go in so many directions. I changed the o-ring on from the PS res to the pump with no avail. The noise is still present. The PS fluid is all frothy and after the car is turned off you can hear what seems to be air going into the pump from the line with the o-ring. I dont really know where to turn from here because I never have worked with the PS system before. Thanks.

 

Make sure there are no leaks in the system and then flush/change the fluid and add a bottle of LUCAS power steering additive !

 

I replaced ALL the fluid with the original Honda product and haven't heard from it in MONTHS.

But if you change fluid and continue to hear noise, I'd look to that froth in the fluid. It means you have a leak in the part of the circuit that is under negative (sucking) pressure. It's pulling air in through the leak - and THAT leaves NO telltale fluid stains on the outside. Start by tightening all clamps and looking for cracks/holes.