Streaming. Okay, I was really concerned that your steering was melting.
There are some possibilities;
There is a pressure switch that changes the amount of pressure allowed to assist the steering based on vehicle speed. Otherwise known as speed sensitive steering. For many japanese vehicles of the early 90's, it is a bypass that comes off the power steering, to a gear drive where the speedometer cable goes into the transmission where is is pressurized by means of the speed that the cable is spinning. It then travels past a pressure sensor switch that, I forget exactly if it bypasses or if there is a valve, etc, to make the steering less responsive at higher speeds so you don't change lanes into the oncoming traffic. There is also a setup that has basically two bypasses with different size restrictor and based on speed, one of the two is used for low speed or high speed.
So, there very well could be an electrical component that is not intermittently restricting the pressure at high speeds and over pressurizing the system.
This is actually pretty likely, the question now is what components is causing it.
Since it is intermittent, I would try replacing the power steering pressure switch, or at least test it with a multi meter. A haynes manual should have the spec to test it.
If it is over pressurizing at highway speed, the high pressure hose could blow and that is not the best fluid to be on while changing lanes at 65 MPH.
I think someone who has experience with Nissans, meaning try to find a repair shop that advertises itself as a Nissan or at least a foreign car specialist, since it is an unusual problem.
Let me know how it turns out.
Wednesday, February 23rd, 2011 AT 8:38 AM