How to you bench belld the master cylinder on a 2000 suburu forester?

Low on coolant

you will have to bench bleed the line to get aall the air out

OK, did you bench bleed the master cylinder before installing? If not, the warranty will be void, and the pedal will drop even if the rest of the hydraulic system is sealed.
I would try another new master cylinder if the bench bleeding was not performed and the master cylinder was deemed to be damaged.

If the master cylinder was bench bled, and it does this, maybe you can get it replaced with a new one under warranty.

Good luck on this repair.

That is a tricky question, adjustments should be done but if you need a new slave cylinder then its a diffrent story as the kit donot come with slave cylinder.

It's usually either plugged bleeder screws or the master cylinder is not pumping fluid to the wheels. It sounds like there is a blockage somewhere and you need to find out if it's at the master cylinder or the wheel.

I’m happy to help further over the phone at https://www.6ya.com/expert/jeremy_69f3cc28d95bf514

Did the pedal go to the floor beforehand? Was the master cylinder leaking, and did you bleed it properly? If the master cylinder was not leaking, check your brake lines going to the rear wheels.

did you hook the big vacum line to booster back in?the master cylinder came w/bench bleeder, did you bench bleed the master cylinder? if not, thats the problem. you'll need to take back off @ bench bleed that master cylinder.

Why were the brake lines replaced?

Sounds like the mastercylinder may have run dry. You have to bench bleed the master and then DO NOT allow fluid to run low, while bleeding brakes...

if master cylinder runs low on fluid and air gets in, almost impossible to bleed with out releasing the lines and bleed master it self.

you should first bench blead a new master cyl before installing it on the car.

it sounds like the master cylinder but belld the freont brakes firdt then the rear this may fix your problem good luck and safe driving if ANY doubt take it to a brake spelist as your daughters life is pressous . Lindz