Santa FE SM (2001-06) :: Hum Noise When Speed Reduced - Power Steering Fluid Leak From Reservoir

2005 Santa Fe (88K, 2.7 V6).

For a month or two, after the car got warmed up, I'd hear a whine/hum noise when I slowed to turn or reduced speed. The noise was much more noticeable when the car had been running at least 15-20 minutes, but I did occasionally hear it when the car was somewhat cool still. Never had a problem steering during this time, even with the noise... but I eventually figured out that slowing down and/or turning brought it on. So I took it to a mechanic.

They showed me bubbles coming from the power steering reservoir, and said I needed a new PS pump and pressure hose, along with a flush/new fluid. I paid for all of that.

Next day: The car would become hard to turn when I made a tight turn into a parking spot... again, not a constant thing, but only when turning to park and going slow. The noise APPEARED to be gone, but this new issue worried me so I took it back. They put a different pump on (no charge), thinking the other may have been defective.

Next Day: I hear the whine again on my way home from work. When I get home, I park, leave it running, and pop the hood. There's a fast drip bubbling from beneath the reservoir cap and running down to the pavement. First thing the next morning I return to mechanic. He says the first two pumps were the same brand and both "remanufactured" so he switches to a different brand -- this one brand new, not "remanufactured" -- and installs that one.

A half hour later, I get home. Hearing that same whine/hum, I lift the hood. Fluid is pouring out from beneath the cap in a steady, unbroken stream (not a drip, but a stream). So I took it back to the mechanic (who to his credit, has charged me nothing since the initial new pump installation). What could cause the power steering fluid to gush out from the reservoir cap when the car gets hot? I have a brand new pump and pressure hose. What could cause this condition..