Have a 1999 and just replaced the master cylinder. I am trying to bleed the brakes but the rear bleeder valves are rusted to the calipers and I can't remove them. Is it possible to bleed the lines by removing the brake lines themselves or am I constrained into new calipers?

 

new calipers, or try and get the bleeders out and replace the bleeders with new if they break.

 

you can try heating them up too. ive had luck doing this lately got some of the crustiest looking ones off that way. if they break you can get new bleeders if you can manage to easy out the old ones. you MIGHT be able to bleed it at the lines. but the lines arent the highest point. if any of that air shoots into the caliper it aint gonna work

 

Not the best solution but it will work in a pinch

have a friend help you, remove and position the calipers so the lines are at the top.
put a wood shim the same thickness or a bit larger than the rotor,
wedge it between the pads and use the line as a bleeder screw.

Following proper bleeding procedures of course,that will get you back on the road.

put some rust penetrant / heat on the bleeders they should break free after a few days of careful working them back and forth

and yes you will go through alot more fluid than you normaly would using the bleeders, so keep your eye on the fluid level in the master cyl.

Hope that helps