Toyota Repair: 1995 Toyota Celica, high pressure hose, power steering fluid

Question
Dear Ted,
I bought a 1995 Toyota Celica Convertible a year and a half ago. I have had problems with it. In January, I began to have problems with the steering. The wheels will make a screeching-grinding noise when i turned the wheel. My grandfather told me the wheels were the wrong size, so I replaced them. The noise did not stop. Then my dad thought it was a plate by the brakes that was bent, so he fixed it. The noise still did not stop. We have run out of explinations and the noise is still there. Any idaes? I would be very apprecitive if you can find a reason for the noise.
Thank You for your time,
Rachel  

Answer
Check the power steering fluid level if it's low there is a leak in the system, the noise is caused by the power steering pump getting air instead of fluid and the power steering belt will also slip causing the loud squeeling noise, add some fluid and see if the noise goes away and check for a leak, a common source of a leak is the high pressure hose but check the pump and the steering rack for leaks also.
I should have asked this first, is the noise there when standing still and turning the wheel or only when driving and turning?