1995 850 glt brake problems
 

ok so i changed all four breaks new rotors bled the lines and all that worked goodrfo awhile

Now after driving the car for awhile I have to press almost all the way down on the brake to stay stopped could it be the master cylinder?

anyone?

Is the pedal spongy or hard when you push down on it?

Does it gradually sink as you hold it pressed?

in the morning its fine like i can stop without pressing all the way down
then after im off work i push all the way down like just right out of the gate im pressing all the way down like the other day my back breaks were locking up and i was sliding around but yeah it feels kind of hard when pushing it but i have to go all the way down also if this helps i live in an area where its been 100+ degrees in the past two weeks so could the break fluid get thin from the heat?

What was the reason you did the brakes in the first place and how did they feel before you did the work ??

Did you have this problem before ??

Brake fluid doesn't get thin. So that one's out.

When you did the brakes, did you do anything to allow brake fluid to bleed out of the system ??

Did you replace any of the calipers, hoses, lines . . . anything that could have let air get into the system ??

The brakes were really bad like the pads and rotors where done! Ive bled the lines twice already there was air in the lines the first time the second time i didn't see any the brakes were worse before i changed the pads and rotors

And yes it does sink as i hold down on the brake pedal.

If the fluid is NOT dropping, and the brake pedal fades, you likely have a problem with the master cylinder.

Did you have the system open ?? Did you remove a line, caliper or hose or leave a bleeder open ??

Did you bleed all four wheels, one at a time ?? Did you follow the Volvo procedure of which to bleed first and what order to go in ??

Did you bleed them with a vacuum pump, just gravity or with a second person ??

Like Rspi said, if it's not dripping someplace, the master is internally leaking or fluid is bypassing the pistons seals and it needs to go.
When you pull it there is also a chance you might see fluid on the back side of it if the rear seal failed and it's been leaking into the big brake booster it's bolted to.

when i bled the brakes i did the normal z pattern starting from the passenger rear wheel (is it different on volvos?) i did it with a second person too

LR, RR, RF, then LF.

Bleeding brake (note spelling) systems that include ABS control units (most cars built in last 20 years or so) by using old two-man method is fraught with peril. Using a pressure bleeder is only way to go IMO, and you don't need a helper!

I.e. you have air in the lines if you didn't have this problem before you worked on the brakes. And you're endangering yourself and others by driving your car in this condition.

I'm guessing this is the problem but I've already asked twice if he had the system open or ran the master out and never received an answer. He replace the pads and rotors from what I can make out but that doesn't tell me if the system was open. The proper way is to break (<-correct spelling) open a bleeder before you retract the piston so the old fluid gets pushed out and not back into the ABS and or master cylinder with any crap that might be in there.
I can' help people with a problem if they chose not to help themselves. :(
I'm not asking because I don't have anything else to do.

And I understand the brakes needed to be done but the OP also hasn't said if this problem was there before he did the brakes.
It's a simple question that tells those trying to help the OP if it could be anything since it was already there before the brake job or if it's a new problem which tells people trying to help that it's something caused by something done during the brake job.