Make sure you have enough fluid in the master cylinder and that it has been bled enough to draw it in -- if you have only air in it, you can go back and forth forever.

You should be able to just open the bleeders with the master cylinder reservior full and apply a bit of vaccum -- this will pull the fluid down nicely. That's what I did on the 280 SE. Open only one side at a time to avoid pulling air across the brake lines though.

Failing that, a traditional bleed with two people will work the best, as any air forced out of the calipers will then cause fluid to be drawn in at the master cylinder.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!