Finishing up touches on the '89 560sl rebuild that took 2yrs of weekends. Looks and runs pretty good if I do say so myself. Yesterday's fun was a closer look at the brakes. I went in armed with parts I knew I had to replace, various printouts from the CD repair manual and an expectation that 'nothing is ever easy'. I was not dissapointed. I went into this activity with working brakes but two probable sticking calipers. I figured I would take off the hoses (previous posts suggested my problem could be related), flush the fluid, check calipers, and replace the front rotors which appeared to be worn down quite a bit. In the process of course I introduced air to the system. My car has an ABS controller that looks nothing like the the one in the manual, so when I attempted to bleed the lines, the manual said to release the "SP" nut on the abs unit to let down the fluid to a prescribed level. Now knowing how far the fluid level was being let down stumped me initially but ok, measure it...but then I realized there is no 'SP' nut on the unit. Of course the unit is buried up in the front of the hood and I can only physically get to it from the top, but feeling around it doesn't produce anything that seems like another bleed screw. Also, I noticed that I can not flush the system with a vacuum tool, drawing vacuum on the lines will not yeild fluid, the pressure will remain, even if I pump the pedal and have the car running. I suspect the ABS unit is doing something that prevents fluid from just flowing but not sure and the manual is no help. Anyone out there done a job like this have any advice?

When I bleed the brakes on my 88, not sure it is differant then the 89, after changeing the hoses, I found you have to pump the brakes real slow, otherwise nothing would come out.

Just an update, I think I have the problem solved. I think this points to the need to flush brake fluid annually because I ended up basically redoing the entire system and everywhere I looked I saw evidence of moisture damage (rust). So the reason I could not get fluid to come out of the rear brakes when depressing the brake pedal was not the ABS system, it was the master cylinder. There are two 'pumps' within the master, the first stage is for the front brakes and the second stage is for the rear...it seems the rear stage return spring was degraded by heat/rust so that it wasn't strong enough to push the actuator back enough to draw in new fluid. I ordered a replacement master from Perf Products, ($160 vs $289 from the dealer), and installed it this weekend. The system bled like what I am used to from that point on. So now the car has a new master, rebuilt calipers, new hoses and fresh fluid. Runs like a dream...now off to the water hoses...