Stiff power steering

[Joy1]

I got a problem with the power steering on my Suburban 1500 1999 mod.
after I install a new pitman arm. When I start driving the power steering is stiff i centre, when I turn left or right I have to help the steering wheel back to centre. When I drive straight a head the steering is stiff and hard, sometime more and less. After driving about 5 minute the power steering is working fine and normal, but if I take a hard turn to right or left, like turn around the car, the steering is stiff and hard again for about 5 minute.
PS. When I install the new pitman arm I disassemble the power steering from the car, and have it in a vise when I took a way the old pitman arm.

I hope someboby can help me with suggestion to solve the problem.
Thanks

[n_lopezIII]

i had the same problem on my 99 sub. when i would make a u turn the steering would be hard for a few minutes. I replaced the steering gear box. and my problem was solved. I suggest to try to bleed the system 1st and recheck. everyone one guessed it was the pump but that wasnt the issue the pump went for another 50k before it went out and when it did it was hard steering all the time. I guess on the gear box since i figured when the pumps bad it bad and hard steering all the time i didnt have that. The gear box has a worm gear type internally and they tend to bind when turning effecting steering for awhile. I have replced quite of few at work due to the same reson. I hope it helps. buy a aftermarket not from dealer had no problems again dealer wants around 500.00 bucks