HELP power steering

I am new to landrovers and spent the winter rebuilding my 90td.
Now that its mot'd and on the road the power steering fluid has started bubbling up out the resevoir cap.Is the sytem needing drained and rebled with new fluid? or is there a bigger problem. Any help would be very appreciated.

Mine will do this if the steering wheel is turned from lock to lock without the engine running, can't think how I found out now. Any how I'd try bleeding it again and check the tension in the drive belt.

Hello.

Thanks for the reply. Will bleed it at the weekend and see if it makes any difference. THANKS