Brake pedal gets soft, but returns to normal after repressing

When i’m coming to a stop the brake pedal gets really soft and sinks almost all the way to the floor, but if i let off the pedal for a second and repress it then its fine. All my pads are new so I know thats not the issue. could my master cylinder be going out? or do I just have air in my lines somewhere? It does’nt happen all the time but it’s been getting a lot more frequent. Thanks guys

This sounds like the master cylinder. Turn the car on,push the brake and hold it,if the pedal starts to fall,its the master cylinder.
Might also be air in the lines,might need to bleed them.

I’ll check that out, thanks man

91_LS- that test you mentioned is only for testing the brake booster.
512_sir II- bleed your brakes, and look for leaking lines and hoses. You can also unbolt the master cylinder from the bulkhead (not the lines) and pull it forward a bit, and inspect behind the master cylinder. If its leaking replace it.

No its not bro,if the booster was bad,the brake would be hard as shit to push. If the master was bad,the pedal would only get hard after you pump it,but will loose its pressure. By pumping it,you pressurize the master,keep foot on the pedal and it will slowly fall to the floor.

And how to check the booster,same concept but without the car on.

that test doesnt prove that it is the master cylinder.
The correct way to diagnose it is to look for leaks. if a line leaks the pedal will drop.
Neither of those articles show the correct testing procedures.

No,that;s why it tells you to check the fluid and look for leaks first. But if the pedal drops after performing this test,the likelihood of it being the mast is great. Air in the lines will make the pedal feel spongy,but the pedal wont drop to the floor all the way (UNLESS THE FLUID IS LOW) and i mean low as in "nothing in the fill cup.

We dont know if there is fluid in the cup.
Now good day to both of you. No point in arguing further.

512_SIR II- you have everything you need on this page. Good luck. :up:

Ha wow guys lol. Alright thanks everyone

Take it from a fully qualified mechanic, a former honda technican and a 92 da6 owner! its your master cylinder seals. when you start driving your pedal is fine, after a while of braking the padal starts to travel, whats happening is as the fluid gets warm it gets lighter thus passing the seals. this problem starts by changing the brake pads and pumping the pedal and pushing the seals beyound there normal sliding area and the grove made by the seals cuts the seals. two opitions, change the seals which can be got from honda and just change the master cylinder completely, the later is easier if your not too mechanicly minded! hope this helps.