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Current issue - Can build brake pressure, but it immediately fades and pedal goes straight to the floor.
Past issue - Last week I was driving and noticed the pedal going much further than usual. Couldn't build pressure in it at all but I could still brake. Get back to the house. LSPV boot was full of brake fluid and leaking. The master reservoir was completely empty. Just gone done replacing LSPV with a used one. Bled brakes & lspv. Order was lspv - DR - PR - PF - DF - lspv....wasn't sure when to do lspv so I did it before and after.
Pumped brakes for a few minutes and didn't notice any leaks. Didn't think I needed to bleed master, but only way is to blench bleed right?
So....?
Is there air in the master that requires me to blench bleed it as well, or did I dry it out?
Wondering if I need to replace it or not, and wanted to make sure this is the next culprit to check.
Thanks for all the help!
Sometimes it does take a while to get all the air out
It could be from a poor connection allowing in air
used LSPV allowing air into the system
I don`t know about bleeding a Master Cylinder the last one I did was back in the early seventies
Never seemed to have any problems over the years
If you feel the need to bleed the master cylinder with help to hold the lines from coming out just use the pedal no need to remove it
You might need to make your own lines to allow the fluid to be pumped back in the reservoir
Then of course you need to start over and bleed the whole system again
Not really understand what your saying when you talk about bleeding master with the pedal and making my own lines?
It COULD be a faulty lspv, but I'd like to think it's not, as the last one clearly had a hole in it (leaking fluid) and it no longer appears to be leaking.
IF there was a bad connection, couldn't I see some sort of brake fluid leak when test pumping the brakes?
I redid and bled my brakes about 2 months prior to this happening, in which everything was just fine.
So would having air in the system still let me pump the brakes and build pressure? It just doesn't hold that pressure but for a few seconds.
Would really like to figure if it's the master before I try to replace that as well.
Could it be the order in which I bled them? Perhaps I shouldn't have done the LSPV twice?
Very confused, and appreciate the responses.
Wouldn't have even been able to replace the lspv without you guys.
You can be drawing air in and not leaking fluid !!!
What I meant was no need to pull the Master Cylinder off and secure it in a vise to bleed it.
Most new or Rebuilt master cylinders would come with nylon fittings and hoses for bench bleeding .
The hoses would be placed below the fluid level in the reservoir so air is not drawn back into the master cylinder while trying to bleed it.
I'll check out the master and see how I can go about bleeding it. I guess I'm going to rebleed everything and see what happens. So whats the proper order including the LSPV and master?
There's the master, appears to be the original. I see no way to connect anything to bleed it.
Demon I'm gonna try to go get one of those today.
Waiting to make a move cause I really don't know which direction to go yet. I mean the only thing I can assume is figure out the proper order to bleed and try it again, or replace the master. Reading a lot of threads trying to figure out the actual culprit.
How do I check if I'm getting air in the system with no visual signs of leaking fluid? Wonder if i should just order a new MC just to rule that out. Not exactly cheap. I did have problems with the bleeder valve on one of the tires, just been using an adjustable wrench to loosen em when bleeding. Bought the wrong line wrenches, thought it was 12-13mm. Seems to be a LOT smaller.
Part of me wants to say screw it and have a shop do it, I'm not very mechanically inclined.
Last edited by Scatterbrain; 09-12-2015 at 11:50 AM.
What you would do is unscrew the line put another line on with the line going into the reservoir below the fluid level.
That is how one bleeds a master cylinder if you think it needs to be done.
Before buying parts figure out what is wrong .
I dont KNOW that I need to bleed the master, I just don't what to do. I thought I did since the reservoir had initially gone completely empty which would let air into the master correct?
Plan of attack here, go get new bleeder valves and rebleed everything. That doesn't work, go get a bleeder kit for the master...That doesn't work, replace the master?
Would anyone try this differently? Asked a mechanic friend and he was sure that it was a leak somewhere ( no idea how to find it besides visible fluid leaking) or just a big ass air bubble still hiding in there some where.
Someone told me to never push the peddle all the way to the floor when bleeding, can anyone confirm this?
I know how bench bleed it, but can this also be done without having to remove the master? I found this :
From page BR-4 V.2 '99 FSM:
Quote:
If the master cylinder has been disassembled or if the reservoir becomes empty, bleed the air from the master cylinder.
(a) Disconnect the brake lines from the MC.
(b) Slowly depress the brake pedal and hold it
(c) Block off the outlet plugs with your fingers, and release the brake pedal
(d) Repeat (b) and (c) 3 or 4 times.
Assuming that just squirts brake fluid everywhere.
Last edited by Scatterbrain; 09-12-2015 at 01:25 PM.
Someone told me to never push the peddle all the way to the floor when bleeding, can anyone confirm this?
The reason to never push the pedal to the floor is to avoid ripping up the internal seals when they travel past their "normal distance", ruining the master cylinder. The inside of the master cylinder can have some nasty build up and pitting especially where the seals don't typically go under normal braking.
You only need to worry about this on an old /used master cylinder because a new ones should be clean and smooth through the entire bore.
If the master cylinder was run dry, you need to bleed it, or it may take forever or it may become impossible to force the air out the bleeders at the wheels.
Try bleeding the master cylinder like you said in the truck. You will need another person to do it: one to push the pedal and another to block off the ports or crack the lines open and closed leading to the master cylinder. You will need lots of rags to catch the fluid. Brake fluid eats paint.Keep the master topped off with fresh fluid or you will need to start over.
Or try the one person tube method shown above^^
Definitely try to pinpoint the problem before throwing parts at it.
If you end up needing a new master cylinder, get an OEM Aisin one. Avoid parts store MC if possible but if you are on a time crunch, you can get one.
WHELP! Couldn't find a master bleed kit that had the right fittings, so I tried using bleeder screws to do it that way. While we were messing with it I could hear air escaping from the master. I could feel a small amount of air coming out from where the master mounts to whatever that disc looking thing is. It's also moist with lots of build up beneath it. So I assume a leak? I took some photos. Cleaned out the female part to where the master inserts, there was a huge build of up grease and debris ( wasn't aware you greased then when replacing)
Also the top of the master seems like its been shaved down (unintentionally)
I don't see any issues with the gasket though. On the car side it looks like theres a square paper...gasket? (Sort of covered in gunk now)
After "bleeding the master" got some air out but still couldn't hold pressure. Didn't bother bleeding the rest cause that's when I started hearing the air.
Should I just replace the thing or try to remount it and rebleed everything. There's a large amount of build up on the entire master, only once I got it off did the inside look surprisingly clean. I hesitate to go to a parts store to get a master, but I don't exactly have a week to wait for a new one to come in.
Sorry for the lapse, problem however was solved! Thanks for the help guys!. So I tried to bleed the master while it was installed but it just didn't work right. Took it out (easy) bench bled it, then bled everything and its all working great now!
FYI - Bought one of those generic bench bleed kits that they sell at most auto parts store, huge ripoff. Toyota makes the two master plugs two different sizes, the kit only comes with one valve for each size. So instead I just bought to bleed valves and some clear tubing and used that as my bleed kit. Cheaper and easier. Hopefully it helps someone out.
09-10-2015 | 06:14 PM
Sounds like you still have air in the system.
