Seems to be a popular topic these days.

I managed to drain the MC by accident during a caliper change. Turned out the r/b caliper had incorrect halves so I have had it changed a few times now. Then bad lines...then bad hoses....then.....Both Ft cali's are rebuilts and are now appearing correct.
I have bled the system 5 times, built a power bleeder and done that twice now. Still light goes on...pedal goes to floor.

I am assuming I have air in the MC. I am now preparing to bleed the MC on-board. Any tips for me?
Do i need to submerge (and keep submerged) the ends of my brake lines that will circle back into the MC or do I only need to observe the flow of fluid/air?

I assume i will do this on-board by caressing the brake pedal? Do I need to cyle the brake pedal or leave it locked down at any point during the mc bleed?
or are there any secret Swedish methods?

This had been a very very painful experience that I am fed up with and it is no longer fun!! But I will see it through.

An earlier post by Vrolvo states a badly adjusted booster screw. Can someone shed some info on that?

My brakes were perfect before I decided to change a caliper and introduce this 4 week nightmare
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420,000KM and still ticking

Are the front calipers on the correct sides? The inner pointing bleeder must be at the top, and it's possible to put the calipers on the wrong side, upside down.
There is nothing special about bleeding Volvo brakes, not even the order, if you know what you are doing. Depress the pedal, open and close the bleeder, let the pedal up quickly. Pause. Depress the pedal and repeat, at each bleeder.

Yes they are installed correctly. Nipples up. Dimples down.
I drove the car for about 50 miles tonight. I would say I have about 80% brakes. Light does not go on. But I still have a problem. When I brake I feel a slight binding and kind of a low frequency humm and you feel it in your butt. Like one side of the caliper is pushing the rotor instead of two sides squeezing. No vibration or anything in the steering wheel and it brakes straight. This tells me the problem is in the rear. Yes?
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420,000KM and still ticking

You may be on to something. I have found several instances in customer cars where a stuck piston on one side of the rear Ate calipers causes the good piston to push the pad over and distort the rotor enough to make it contact the fixed pad. Over time the pad wear causes a huge gap which is taken up by master cylinder travel, making the brakes feel spongy, even though there is no air in the system. Pull the back wheels and confirm near zero clearance on the pads on both sides. Have some depress the brake pedal (engine running) HARD and observe the rotor edge.

See my recent post
http://www.brickboard.com/RWD/volvo/1288202/220/240/260/280/brake_problems_1990_245.html
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1980 245 Canadian B21A with SU carb but electronic ignition and M46 trans in Brampton, Ont.

I have a method that has always worked for me. I have never had a problem result from it, but it is my own invention. In fact it works so well I don't bleed any other way. I put worn out pads in the caliper being bled and then use the brake pedal to pump the caliper pistons all the way out. Crack the bleeder screw (or screws) and push the caliper pistons in until brake fluid comes out of the bleeders and close them. You don't need to bleed much fluid out since the air will always be on top in the caliper. All the air should be out of the caliper with one cycle, but keep repeating this until you get no more air out of the bleeders from the brake lines. Then just pump the caliper pistons out again and then push them back in with the bleeder screws closed. This will push any remaining air in the lines and in the MC into the MC resevoir.

I think this technique works so well because you are not trying to push air bubbles down where they don't want to go. I also like it because it does not require any tools or an assistant to pump the brake pedal, and you don't risk damaging the seals in the MC by pushing the pedal too far.