2012 5500i International steering issue

I made a few trips north in a star like that, which ever way you pointed that thing was where it went when you turned loose of it. It was bad enough that I had a flat on the right steer, and it didn't even try to pull that direction until after the tire was ruint. I felt it slip a little when I turned into cold foot and looked after I parked, the tire was almost flat with knots bulging all out of it.
We tried everything, eventually found out that the power steering filter had came apart on the previous owner and went through the system. I heard later that it took a gearbox to fix it, but don't know for sure as I never drove it again.I will say it was freakin dangerous.

 

Sticky steering shaft or low caster will also cause this.

 

The pump itself will not cause the steering to not return to center on it's own while rolling. If the front end is free as you say, have the alignment checked. You should be able to turn the wheels lock to lock with the truck not running and axle up on stands. Not from the steering wheel, but from the tire. Any spring work recently? Shims left out by accident?

 

Lack of caster can cause the steering not to center correctly but you'd likely have a front end shimmy going down the highway (think wobbly shopping cart caster wheel).

Its been a while since I studdied up on alignment angles but I believe kingpin inclination plays a role in the steering self-centering. When you turn the steering wheel, the angle of the kingpin actually causes the front axle to lift slightly. This downward force helps to re-center the steering.