The surest method I know to test a MC is to "deadhead" it and hit the pedal.

To deadhead a master cylinder, you install blind plugs in place of the two lines and push the pedal. Because the plugs are blocked solid, there's nowhere for the brake fluid to go. A good MC will have a high, rock hard pedal. It won't budge even 1".

I made two blind plugs by cutting off the lines from a junked car, crimping them over about 1/2" down from the flare nut, and brazing them closed.

A master cylinder will eventually bleed itself, but it's smart to "bench bleed" it before installation. That way you avoid pumping bubbles needlessly through the system.

I hear over and over that Volvo recommends a certain sequence for bleeding the system. I confess to not knowing it and therefore not using it. Perhaps I've just been dumb, stupid lucky for all these years and all these Volvos.

I hope the original poster double checks what Art Benstein suggested -- the right 'n left front calipers mighta been swapped (BTDT), which makes them impossible to properly bleed. They'll fit fine otherwise.
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Don Foster (near Cape Cod, MA)