my 840 had a power steering leak from the pump,i had it rebuilt,now the brakes are workn right (since it's all workn together)the resevoire is full but no steering assistance. can any one help me

You should ask that question on Roadfly--there are only a couple of owners here and a lot there. http://bimmer.roadfly.com/bmw/forums/e31/

What type of Pentosin do you use? I am guessing 11S. Has the reservoir been refilled with the correct type of Pentosin?

There could also be a trapped air issue. Try the following:

1. Turn on the car.
2. Turn the steering wheel lock to lock (Full right than full Left).
3. Turn off the car.
4. Open the hood and open the Pentosin Canister lid.
5. Pump the brakes 24 times till the pedal gets hard.
6. Look in the pentosin reservoir.
7. The fluid should be halfway of the metal mesh screen and be Light Emerald Green in color.

If the fluid level or color shows different post here and I will try to help further.

Regards,

i used 11s,when i pumped it the fluid does come up,seems to be enough,the pump is also not making any of that whining noises that usually come with low fluids,.at very first when leak was still intact i applied some fluid to move the car,and it worked fine,just needed more fluid,but now ,no dice.if there is air in the system how would i go about bleeding the steering line?

Bleeding the steering line is a hard job. It is out of my capabilities. Maybe a drive to the mechanic is in order.