2000 Taurus Power Steering pressure

The pressure in my power steering system appears to be excessive, at times fluid will release from the top of the cap through the hole in the cap, when you turn off the car. The cap is also hard to remove becaue of the built up pressure.

What causes this?

Air trapped in the system. This can happen when a leak is present or when turning the steering wheel with the vehicle engine not running.

Try bleeding the air out with a vacuum pump.