93 civic dx brakes

[1993civicDX]

hello, i have a 93 civic dx and sometimes the brake pedal moves slowly to the floor, has brake fluid put some in a while back since I thought it might have just been low. any idea what could be wrong?

searched for answers and got a little info but not sure what I should check first lol

 

[Deezy]

Start by bleeding your brakes....If the problem persists, then swap in a new master cylinder....

 

[CivicPartsGuy7]

Ive got a master cylinder and booster for your car. 20$ let me know

 

[2NRSTV]

It's most likely your Master. If it feels hard at first, but then slowly sinks to the floor, then it would be your Master.
This is caused by your initial pump holding pressure, then fluid will start to leak past the primary piston cup back into the reservoir and also into your brake booster.
Mostly, if it was air in your brake lines, the pedal would feel squishy.