brakes went out do to loss of fluid the other night added fluid bleed the breaks, they only work when you pump them 3 or so times then they work awesome. replaced the master cylinder and the problem wasnt fixed. brought it to les schwab for a break test they told me at first i didnt bleed them right. so they ran about a gallon of fluid through and said the master was bad... i really dont think thats the problem so i went to orileys where i bought the cylidner and they said they would replace it but they dont think thats the problem. any ideas? im stumped

 

where did you lose the fluid?

 

Not sure itl was slow leak I know my clutch cylinder leaks a little behind the firewall

 

Well if you have a slow leak it will be able to suck air into the system making it near impossible to bleed your brakes.

Find the leak!!

I would also make sure your E-Brake is working and the rear brakes are adjusted up which can make a big difference in pedal feel

 

i found a leak where the master cylinder meets the brake booster.. could this allow air to enter and not probably bleed them? even when i replaced my master cylinder the problem stayed the same. which makes me believe it is not the master cylinder and possibly the brake booster.

 

When you replaced the m/c, did you bench bleed it? Did you see the leak on the outside at the joint btwn the m/c and booster or did you see the leak only after separating the m/c from the booster? Is there brake fluid in the booster?

The booster itself cannot cause a fluid leak. Its the seal around the primary piston in the m/c that would result in fluid in that area - reman'd m/c I am guessing. As much of a PITA as it is, I would exchange the m/c with another one if you have brake fluid exposed around the mounting flange area.

Does the pedal slowly go to the floor when you hold the brakes at constant pressure (engine on)?

 

i dont remember seeing the leak, and by bench bleed do what exactly do you mean? i think im gonna put one more m.c on it tomorrow . and ill try and explain what the pedal does as best i can.. this is with the engine on. the pedal goes to the floor and the backs lock up if you really press on them hard.. but if you pump them 3 or 4 times the work great.. and if you pumped them 3 or 4 times and hold it down a little the pressure stays. but a soon as you let go its gone.

 

Don't forget to check the Load Sensing Proportioning Valve. It is on the passenger side above the axle on the frame. My '88 had no brakes and I changed the m/c and nothing happened. I then noticed the ball of rust above the rear axle.

Although the LSPV may have something to do with it, I would go ahead and bench bleed first. LSPV's are very hard to find. Only place I found mine was from a junk yard in Wisconsin. good luck

 

Bench bleed what you have first. Do a search here or on google for "how to bench bleed a master cylinder". You should have gotten some clear tubing and plastic tube fittings with the new master cylinder. Those are for bench bleeding. You have to make the master cylinder 'wet' and remove the air before you install it. Bench bleeding does this.

Good luck.

 

I just had the most frustrating brake experience ever and it kind of sounds along the same line as yours.

Last week my pedal got really soft and would only work after I pumped it a few times. This past August, I redid the entire front (wheel bearings, seals, pads rotors etc.), but never touched the back. So my first check was the back breaks and found my right wheel cylinder leaking very slowly. So I replaced both sides and put new shoes on. Still had a soft pedal. I did not suspect the MC because if I pumped the breaks, the pedal would hold steady. So I just kept bleeding and bleeding and it got me nowhere.

In frustration, I got a new OEM MC and put it on and bled the brakes. Well my soft pedal went away and the brakes work fantastic now. I took apart the MC to see what was up and I could not see any apparent failures in the seals. I can only guess it was leaking internally somewhere. I have no idea what went out, but it was a bad MC.

I bench bled the MC just by plugging up the outlet holes with my fingers. When the pedal was depressed, I let the air escape past my fingers. When the pedal was released, I plugged the holes so no air went back in. I did this about 5 times before I got pure fluid out of the MC.

Hope this helps...Breaks are one system that I would not hesitate to replace parts until it’s fixed. Just for the principle of safety alone.

 

Most master cylinders come with a brake bleeding system, and instructions on how to do it.
I know that the napa ones do.

 

make sure the rear brakes are adjusted first. then bleed the m/c followed by left rear, right rear, left front, right front then the LSPV. you'll probably go through 1-2 quarts of brake fluid.

 

turns out it was the wheel cylinder. the leak most have been small at first because i saw no fluid. but i got home last night from work i pulled it into the garage and noticed my rear driver side tire was covered in fluid. so i getting my rebuild kit today and hopefully this will solve my problem

 

okayy im really stumped now! the wheel cylinder did not fix it so i put on another m/c bleed it . and it still feels the same.... could my calipers be letting air in. they are not leaking and my brakes work great when i pump them . this could be a job for a professional

 

Make sure all your bleeders are in good shape and not letting any air in.

 

got new ones with the wheel cylinder and cleaned the front two

 

bleed everything again, and this time, include the LSPV. Be sure to bleed the line in the LSPV that comes from from the front brakes. Basically, every connected joint in the brake lines will need to be cracked open during the bleeding of the entire system, and eventually, you will be able to work out the air.
Read this entire post for more information:
https://www.yotatech.com/forums/f120...eeding-244093/

 

thanks for the link. ill guess i try it again tomorrow.. these brakes are consuming my tresured days off work! i just wanna go wheeling!

 

are your brake pads getting fluid on them? are you replacing them when they do?

 

not sure what you mean.. front or back pads?