MuddfreaksOffroad

So my dad has a 89 toyota as many u probably know, well he has had this odd brake problem. what it does is when u start it and press the brake pedal the brakes SLOWLY go to the floor. NOW the truck still stops not quite as well as it should ... and if you pump the pedal it comes back up but then goes back down. My father and i been trying to figure out what it is, we have several ideas i just want some more opinions before he takes it to his mech to see what it is then imma replace it. I think it could be the brake booster, or a leak in the incoming booster line ( air line ) or maybe air in the brake lines?? idk its confusing cuz if you rev the engine up a lil and push the brakes it SOMETIMES brings the pedal and sometimes not so much.

so let me know your ideas guys help me figure this out lol

rusche

Sounds like a bypassing primary seal in the master cylinder to me.

abecedarian

Sounds like the master cylinder to me too.

mmcpeck

Yup, master cylinder.

MuddfreaksOffroad

ok but its not leaking any fluid ... idk if that makes a difference or not to your answers but thats not too bad. lol Ill have to look around for new master cylinders see how much they cost.

rusche

Theres an itty bitty primary seal in the master cylinder.
When it leaks, its usually small, and it leaks internal, there is no fluid loss.

MuddfreaksOffroad

o hmm but hes not loosing any fluid in the master cylinder resevour? but then again if its little then i can see it not being noticable. HMM so would u suggest replacing the seal only? or getting a all new brake master?

swampfox

your master cyl might be leaking into the brake booster. unbolt the master cyl. and slide it forward enough to see if there is any fluid between them.

MuddfreaksOffroad

k well im in school so i wont have time to do that till prob friday but ill let him know and maybe he can do it himself.