Foaming at the mouth

[Drivfour at aol.com]

My 1987 5ktq turned out to have a loose connection at the swage on the inlet 
to the hydraulic pump.  The fluid ran low and I topped up the resevoir, drove 
home changed out hose and refilled res.  I started up car and turned wheel 
lock to lock several times.  The fluid foamed up to the top. Shut engine off, 
let sit for 15 min and drove car for ten min.  The fluid level was at it's 
correct height at the start, but foamed right out the top.  What am I doing 
wrong????
JD