If the Master Cylinder is the old one some say to start the Engine so that when you sep on the pedal the pistons in the Master Cylinder do not travel into territory inside over the gunk or pits that they don't go over in normal use.

Don't know if it is still called bench bleeding when it is still on the Car. But, pile some rages under the Master Cylinder to catch the Brake Fluid that is going to leak out.

Loosen all of the fittings at the Master Cylinder (Engine running) enough so that fluid can come out of them. Have someone push down on the Brake Pedal all the way and hold it there Fluid should come out and then stop when the Brake Pedal bottoms out.
Then you tighten the fittings at the master cylinder then the brake pedal is released and it comes all they way back up sucking fluid down into the Master Cylinder.

Again loosen the fittings at the Master Cylinder Have someone press all the way down on the Brake Pedal and hold it there. Fluid should come out and then stop when the Brake Pedal bottoms out. Then you tighten the fittings at the master cylinder then the brake pedal is released and it comes all they way back up sucking fluid down into the Master Cylinder.

Repeat the above until you feel you are only getting a solid stream of fluid as the brake pedal is press down. Then you tighten the fittings at the master cylinder then the brake pedal is released and it comes all they way back up sucking fluid down into the Master Cylinder. You are done.

You can do the same as the above on each caliper starting with the most distant Caliper from the Master Cylinder working you way through the other Calipers and ending with the Caliper closest to the Master Cylinder.
But you will be loosening and tightening the Caliper Bleed Screw. Loosen Bleed Screw before stepping pushing down brake pedal, push down on brake pedal and hold it while the bleed screw is tightened, release brake pedal and repeat till you get a steady stream of fluid out of the bleed screw and tighten.

When I was a Kid I had to do the pedal pushing for my Dad. Boring and tedious but it works.

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84 300D, 82 Volvo 244Gl Diesel