with rferance to changnig the pas pump, is it a case of draining the fluid and bolting on/off pump?
Yes, plus you may / will need to bleed the sytem when it is all back together.
whats there left to bleed if i have drained it before removing the old pump??
When you refill it, bleeding it gets any air out.
ahh gotcha 
No worries, I have fitted a few in the past, feel free to pm if you need any info.
