This just started happening two days ago outta nowhere.. But when i press on my brakes with the engine running, pedal nearly goes to the floor, goes about 3/4 of the stroke length till i finally get resistance, and pumping 2 times or 10 times does nothing to get it firm, and doing a hard hit with my foot gives me about a split second of resistance, then bam its back on the floor.. Not only that, but when the engine is OFF it does the same thing, a little bit harder pedal, but still goes down to about 3/4 of the stroke length and stops, pumping it 20, 30 times makes no difference.. With the way it is though, i can still use the brakes, theyll hold that little bit of pressure down at the botto for as long as i need em too, and i can still lock em up, as i found out last night during the rain.. But I Pump bled the brakes earlier till new fluid came out, and still the same result, no change.. Im pretty sure that this is a bad master cylinder, but moneys tight right now and Id like a couple confirmations or ideas from more knowledgeable members before i buy a new mc..

 

Prolly the seals in the master cylinder are bad. That's my guess because if you slam on the pedal you get some resistance then it fades out because the seals are allowing fluid to bypass causing a soft pedal. My two cents...

 

x2 You can also unbolt master cylinder with steel lines attached and pull back master gently and check for brake fluid (moisture) around piston. If so its probably the master.

 

Alright, so what would be the best brand to go for, since ill be buyin off rockauto? beck arnley, raybestos, wagner, cardone?

 

My first choice would be an Aisin, but the others are okay too. Are you going re-built or new?

 

my first choice is always aisin or oem, i got a thick stack of dealer invoices from oem parts ive always gotten, but my clutch slave, brake master, and power steering pump all decided to start goin out right after i blew my knee out and was forced onto disability, and aisin is a bit pricey, so im looking for quality but not so expensive..

 

preferably new..

 

Yeah, sounds like the master if it happens regardless of boost assist. Try an OEM parts supplier like toyotapartseast.com to get near cost prices over dealer list! Good luck, don't forget to bench bleed upon installation!

 

Got it all up and running a couple days ago.. Musta been shot for awhile, cuz the pedal has never felt so firm and responsive.. Brake fluid was a dark brown as well, so im glad I bled all the old stuff out and got the new stuff in, 2 new quarts worth now sittin in the lines.. Thanks for the responses guys..