IIIIllIlIllIIllI

First off I have done my due diligence of searching and a lot reading. Here's some background, I recently purchased a '95 4runner and have been working to get it all fixed up. When i got it the brakes were dismal. So far I have checked all lines and replaced a few suspicious (ie badly rusted) hard lines, replaced the master cylinder with a new non-rebuilt one, checked wheel cylinders, calipers, pads / rotors and shoes / drums. No leaks or stuck caliper pistons. I have bled the brakes Quite a few times, both with truck off and on (yes I followed the correct bleeding order as per the fsm and bled the LSPV). I also checked the brake booster to see if it was leaking vacuume, and it seems to be working fine. I also checked to make sure the rear shoes were adjusted properly. Issue is now, with truck off the pedal is rock hard, with truck on the pedal goes nearly to the floor. It will eventually stop givin enough distance, but not well at all. I noticed that while bleeding I seem to get more pressure out back than up front, also when putting the pedal to the floor at 55 mph the abs engages on the rear brakes and it seems as if the front's do not grab too well. Right now I'm leaning towards internally bad flex lines (they look ok, no bulges or leaks when brakes are applied) or possibly a faulty LSPV. I was wondering if anyone might have any other ideas, as I'm just about out. Any and all input is appreciated.
Thanks, Jake.

justin_4runner

i know u say new master but it could be bad, but it more sounds like air in lines still, when u did the bleeding was it with a vacuum pump or just a hose off the the drain plug?

IIIIllIlIllIIllI

Bled with a rubber hose off the drain plug, filled hose with fluid then submerged other end in container of old fluid so I could see if any air came out. I've bled well over a quart of fluid through the system so far (after refilling the new master).

The MAN

just want to make sure.... before you put your new master cylinder on, you bench bled it right?

If you did, I'd look into a bad proportioning valve also (not the LSPV, but always possible that could be bad too)

IIIIllIlIllIIllI

89pickumup

with all that pedal travel and replaced lines and no fluid loss id say air i would think if the booster was bad youd have a hard pedal even if running
id try gravity bleeding take cap off fill resivor open bleeder and let fluid push itself out a wheel at a time dont push the pedal
air travels up so jacking the vehicle up on the end your working on or parking on a grade to help the air get itself out works alot of times for me
i normally start with the farthest wheel and work my way in

IIIIllIlIllIIllI

Well today I made a run to the local U-pull it and acquired a nice looking LSPV (mine is rusted beyond recognition) and a few other misc things. Hopefully this week I'll get a chance to swap it in and gravity bleed everything. Thanks for the ideas feel free to keep them coming, I'll post back after I'm done.

rworegon

Oops! I just re-read OP mega paragraph and noticed that my suggestion below was already done.

Are the rear shoes properly adjusted? If not, you are having to push the pedal down further to move more fluid to the rear cylinders so the shoes can move the extra distance.

S.Skinner

iTrader: (1)

Subscribed. Same issue here, no line replacement tho as mine look pretty darn good for a 23 y/o truck. New rotars/pads/drums/shoes/wheel cylinders and MC. MC was bench bled and all 4 corners were bled aswell as the LSPV in accordinance with the book. Truck off = hard pedal. Driving = 2-3 pumps b4 good pedal and thats intermiten. somtimes it just stops like a champ. Staying stopped for a while tho as i lost the engine this am on the way to work. good luck and hope to figure this issue out soon.

JamesD

If you guys have ABS it might be two things, the ABS unit or a bad power steering pump. They will give you the symptoms some of you are having. The ABS unit is controlled by the power steering in which I have no idea how it really works. If you look at your ABS unit you will notice power steering lines going to it. These units fail often and usually they are bypassed.

James

IIIIllIlIllIIllI

Problem Fixed:
This weekend (after nabbing a few parts from the junkyard) I replaced the LSPV, and both front and rear soft / flex lines, then vacuume bled the brakes in order (bled a ton of fluid through it, esp. out of the rear). Now I have brakes again! Not sure what exactly fixed it but the above combination worked. (Oh, and the rear ABS works, got it to kick in a few times during my road testing)

New Problem:
After several HARD stops i noticed fuel leaking from the pass. side frame rail (literally coming out of a hole in the bottom of the rail) between the front tire and front door. I have No clue where it is coming from or how it is getting into the frame rail, looked around and can't find a fuel leak. After letting it sit I started it and drove around several times and no leak. Did some more repeated Hard braking and leak apeared. Second time I let the pressure out of the fuel tank (unscrewed cap) and leak stopped. Any ideas? It only leaks after repeated hard braking, let the truck idle and drove around the yard for almost an hour with no leaks...

Fixed my gas leak issue too, THANK YOU search function. Turns out I had crossed the vent and return lines going into the tank when I dropped it the other day, this was causing alot of pressure to build up in the tank, which then pushed fuel out of the charcoal canister instead of vapor, apparently the canister dumps into the pass. side frame rail somewhere.