got my 4 cal's rebuilt for under $400, hooked them up, bled them, not much air came out

if i pump it fast it will feel stiff but my foot will go to the floor in park

if i leave it for a second and push it will go right to the floor

my front brakes seem to be working fine but the back dont work at all.....

Your master cylinder reservoir may not be full enough to keep the back half filled. This is difficult to see, but once you see and understand how that works it is easy to keep the level up. Another thing is the calipers may be reversed, left for right etc. That will place the bleeder below the high point and won't allow bleeding to be successful. Also check the search function for other threads on this general topic.

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1961 190Db retired
1968 220D/8 325,000
1983 300D 164,150