My 2004 Crew Cab Z71 5.3L was purchased with 110,000 miles from a Craigslist ad and the previous owner warned me that it has had no power steering assist at parking manuevers and moans and groans only at low speeds (I said stupidly, "no problem"). I now have 116K miles, and I've decided enough of the "no assist and bitching and complaining by me and the truck". So far it has no leaks, and the fluid in the reservoir is full, but the fluid is dark and somewhat red (smelled like burnt transmission fluid). I checked the steering pump pulley (looked good) and even replaced the serpentine belt. I checked all the front end components and they checked out okay too, and I even greased all the zerk fittings. On Saturday May 31st, 2014, I decided to extract the old fluid from the pump reservoir with a hand pump type of fluid pump extactor and emptied the old fluid in a clean bucket. The fluid that came out was a blackish and dark red fluid resembling burnt ATF fluid, due to the smell and a little bit of black pasty residue. After this, I placed a plastic cup under the return line going to the reservoir, disconnected the return line and emptied even more of the nasty old fluid. I then put a 3/8 rubber plug vacuum cap to plug that metal tube off the pump, and with the return line I placed a barbed type of brass 5/16 two way connector union to connect a 5/16 fuel line that I got from Napa which was about four feet long. I then routed this hose under the truck and into the catch bucket. I then filled the reservoir full with new O'Reillys power steering fluid (GM equivalent) I then jacked the front end up and placed the truck on jack stands. At this time, I turned the ignition switch to the on position (not running), and turned the wheel left and right, lock to lock. When I first turned it, it was hard to turn, then I heard a loud gush of fluid enter the catch bucket with more of that black and burnt fluid. Then I immediately noticed the steering becoming easier to turn in either direction despite the front wheels off the ground. I check the reservoir and topped it off again with more fluid and turned the wheel to the left and right until I saw clear stream of power steering fluid exiting the hose going into the bucket. I also had the wife start the truck and turn the wheel both ways all the while looking at the reservoir to see if the reservoir was still full, and did so safely to flush it even more. Then I filled the reservoir to full cold and took it for a test drive, and wow what a difference. The steering felt so smooth and took only one finger to turn it while manuvering it at low speeds and best of all no groaning and moaning from me or the steering. All this went fine until about I drove it for a few miles. I checked the reservoir and it was still clean and was full (full hot). Now the steering is taking two hands to turn and there seems to be no power assist at low speed during parking lot manuevers or just low speed turning. This is why I decided to purchase a new AC Delco power steering pump (no hydroboost), and I also purchased a pulley installer and remover tool as well. I hope this rectifies the problem. I ordered the pump from Amazon as well as the tool. I haven't recieved it yet, but just from the fluid flush, there are no more moaning and groaning sounds when turning at low speeds, and the hard effort to turn is not as bad (still hard to turn) as it used to be. I did check for leaks at the cooler, and all the lines, and there are none visible. I used a lot of brake cleaner around the steering box, connections of the lines, and the pump, and all looks good without any trace of leaks. I will keep you all updated when I get the pump installed.