93toyrunner2

Thought - Have you adjusted the rears? How much travel does your E brake have when engaged?

xxxtreme22r

I don't know about the O.P. But mine is fine. That's the first thing I adjusted.

waskillywabbit

iTrader: (-1)

X7,067,987,432.658762

:wabbit2:

xxxtreme22r

New master going on tomorrow for me at least.

xxxtreme22r

New master cyl on, brakes bled and still pedal catches low unless I pump with vehicle running. Would a small vacuum leak in the booster cause a soft/low pedal on first pump? grrrrrrrr.

My idle does jump slightly and back down during brake pedal travel. But thought that should cause a hard not soft pedal. Kinda confused here. lol.

Still kinda confused on this post.


Are you saying bleed from front to back? And if I crack thefront/rear lines at the master nothing should come out if properly bled?

Ive tried pumping pedal till hard (blocking pedal down) and bleedng that way as well as "vacuuming" the fluid though the lines while running and leaving the pedal up not pumping.


No air sees to be coming out of my lines currently. However unable to bleed LSPV due to a busted bleeder screw.

snobdds

Your getting air into the lines somewhere. Are you sure all your bleeding screws are air tight and not letting any air back into the system? The broken LSPV bleeder screw might be your problem.

xxxtreme22r

No air coming out of my lines while bleeding.

This is what the "broken" bleeder screw looks like on my LSPV. Doubt that's enough to cause an air leak. However, might be air in that front to back sensor line. I just don't know how that affects pedal feel. Because if that LSPV doesn't sense front line pressure it should shut it off and only use back. Which I shouldn't feel in the pedal while sitting still.

snobdds

If it was me, I would get all new bleeder screws and gravity bleed for at least an hour. Then do the normal bleeding and see if that helps.

I know these systems are hard to bleed. I have struggled with it myself.

xxxtreme22r

bleeder screws on the rears are less then a year old. Came with the new wheel cylinders. Pretty sure I replaced the fronts as well a year ago when I did the brakes. Beginning to think possibly I could have blown a front caliper piston seal, but I don't see any fluid leaking from anywhere.

LSPV has that screw and the bleeder part is completely separate and not replaceable I believe.

peow130

Try bleeding Drivers side rear, passengers rear, LSPV, then drivers front, and then passengers front.
I do my bleed pattern that way, and have never had any issues.

93toyrunner2

Suggestion - Pull your rear drums, and check for out of round. If you don't have the meter to do this, the local auto parts might be able to put them on a drum cutter and once they start spinning, you can see out of round immediately (hear it at least). Put them back on, adjust them until you have constant pressure when spinning the wheel, and back off the adjuster 2-3 clicks, just until they are not making any noise when spinning the tires.

xxxtreme22r

Yayyyyyyyyyy!!!!!!!! I think I gots my brake pedal back. Gotta test drive it yet, can't till I fix this damn tire that I have "issues" with the bead and mud and etc etc in it. But feels much better now. Musta been air in the front pressure sensing line going to the LSPV. Took the line off bled it that way. I am sure there is still a bit of air in there but it's 98% better now while running and sitting still at least.

So to the O.P. BLEED THE LSPV LAST.

wyoming9

iTrader: (1)

Interesting I have done numerous brake jobs on these trucks i have only tried to bleed the LSPV one time ever on any of these Brake systems as It was for a friend it was quite expensive for the new valve and hardware.

I have seen air being drawn in with no or very little fluid loss enough to cause major frustration in bleeding brakes due to a bad flare or stripped threads.

Now I bleed brakes alone with a KD vacuum bleeder starting with right rear left rear right front left front.

Now on the newer trucks the LSPV is on the left side and the older on the right so It takes extra time to bleed the front side the the LSPV is on.

It might take 2 or 3 times around to get it all bleed to my liking.

Another trick I use is to put a vise grip with the jaws ground smooth on the rubber line to keep fluid loss as low as possible . Unless it is time to be changing brake fluid .

Your rear brake shoes must be adjusted up to get a good pedal when doing rear brakes I always install new drums and as the e-brake keeps the rear brake shoes adjusted it must be used or the rear brakes get out of adjustment to the point they no longer work. As they make no contact with the drums.

93toyrunner2

Awesome job. Glad to hear it. So, lesson learned from this thread, bleed, bleed, and bleed some more. Bleed each and every connection in the system several times if that is what it takes.

wiseguymmiv

So I'm going to tackle bleeding my brake system after installing a new brake power booster, and bench bleeding the master cylinder. The FSM says to bleed the LSPV and BV after the wheels are bled.

Q1: What is the BV? Where is it? Anyone have a pic?
edit- I found it in the FSM, but it doesn't tell how to bleed it. BV = Bypass valve on the LSPV.

Q2: Where can I find the LSPV on my 1995 4runner? I saw the LSPV pic in this thread, but not under my rig.

BeenYota

Dealt with the dreaded loss of brakes last year due to my master going out. Replaced the booster first thinking it was for sure the reason for lack of pedal which did nothing, replaced the master and brakes returned.

Haven't had an e-brake installed since I bought the truck and have noticed the passenger side rear drum make subtle contact that has left me stranded on the ice in the middle of the lake on occasion. (Installing this week)

My master brake housing went from a silver to a rust brown color over the course of 2 months since install... I have NOT noticed any brake fluid loss, however I am losing my pedal and brakes again. The front passenger bleed screw may be stripped due to it being an origional part from 92 and the jackass who made the repairs last while I had an emergency. You'd think they would have mentioned something..

Doesn't anyone here use the stainless nipples with the spring and ball bearing for 1 man brake bleeding????

wiseguymmiv

After changing out the power brake booster, bench bleeding the MC, re-installing it, bleeding RR, LR, RF, LF, and LSPV, I now have more braking power than I did before the new power booster was installed, but the brakes are still spongy. It takes me too much distance to stop when traveling at 40 - 50 mph. I also hear a slight air noise when pressing the brake while the truck is running. It is much less of a noise than the old brake booster made, but still seems like it is too loud. Suggestions?

The stealership suggested I spend more than $3000 on a completely new brake system, front to back, so they are no help. They can't bring themselves to say "We don't know what is causing your brake problem."

GuitarMike

Sounds like a vacuum leak! That is provided you have ALL the air out - it can be sneaky that way, and you may still have a tad in there, which WILL make it spongy. It just takes tweeking to be sure it's all gone (and a lot of fluid).

When I pull rear axles or anything, I cap off the line (NOT the fitting, I push that back a little) with a small "bolt protector" - a little rubber cap I found in the hardware store. It's like a thing you'd put on bolts on a swingset to keep kids from getting cut on protruding bolt ends. I got 3 sizes....the smallest force-fit over the line, and I lost ZERO fluid after a week with nothing attached! Put axles back in, quick bleed (5 mins)...back on the road. Something to think about.
I once bled my MC dry overnight - NEVER AGAIN. WHAT A PAIN!

FWIW- during my last 'take it all apart' moment, I pulled the LSPV, cleaned it up all nice and perty...then held it GENTLY in a vice, applied heat to bleeder from a propane torch, followed by ICE water. Not enough heat to travel and melt the rubber internals, tho! But this freed up my bleeder nicely.
Then I tack welded a plate to the bolt flat on the LSPV rear (NOT the LSPV body!), and attached the unit to my frame w/self-tappers after putting the lines back on. My mount was rusted away, so had to do this....
Flushed it all out w/brake fluid when I was done, before re-installing lines. Works like a charm now! No more floppy BS to ruin the lines. Much better than the bungee method, LOL.

If yours is THAT crusty, you might want to check out how well-attached to the frame it is, before it pops off and takes out some lines...

wiseguymmiv

I agree; vacuum leak or some air remaining in the lines.

Full disclosure: I couldn't get the push rod extending out of the power brake booster to turn in order to make it longer/shorter, and was afraid of breaking part of the new $250 booster, so I just left it at the preset distance. I also did not test the brake pedal distance once I had everything back together,as it was getting dark and I'm working outside. Could those cause a spongy brake feeling with slight air noise when the brake is pressed? I wouldn't think so, but I rarely do this level of mechanical work myself.

Someone told me today I should "gravity bleed" all lines at the same time and then refill them. Has anyone used that method? Maybe I'm a little slow today, but I don't understand how that would work. Would that involve no use of the brake pedal to push out the fluid, then tightening all bleeder screws after they've bled out, then bleeding the MC, RR, LR, RF, LF, and the LSPV all over again? Am I missing something?

GuitarMike

I've ACCIDENTALLY used the 'gravity bleed method'...by leaving lines disconnected overnight, and coming back to a dry MC!! All I can see that gaining you is losing ALL the fluid (if any is junk, ok, it's like a 'flush' I guess, and that is good but if it's clear, it's good).

If your MC went dry, I'd suggest bench-bleeding, right off the truck, with 2 lines run back into the reservoir. After I went dry, that's what stalled me up! Only takes 3 to 5 pumps, and you'll see the air come out. Then reconnect the MC and lines, and bleed the heck out of everything...I mean, like 1/2 to 3/4 cup of fluid out of each bleeder, Drivers Rear, Pass Rear, Pass Front Driver's Front.....farthest first, remember....then LSPV. At times I have bled the LSPV first, and then last too, for grins, just to get things moving. I've experienced clean flow, done the same fitting 2 more times, and THEN hit a couple of whopper bubbles...then no more. So it can be tricky.

An "air noise" really makes me wonder if you have a vacuum leak....can you search for it before you remove the MC to bench bleed? Might save you a lot of work for nothing! If you get ANY brakes, you're probably at least close to done bleeding.

Another thing I did (and do) is leave stuff sitting a day or so, and look for leaks at fittings/unions that might be letting air in.

I'm surprised this is killing ya so bad, man - first time, ok, should be a pain, but by now I'd think you'd have it, having done it many times, which leads me to think vac leak, or that pushrod.....

Last thing before removing MC etc. - did you crank out your rear shoes to Juuuust rub the drum, before bleeding etc? I've found that, on jackstands, you can roll the tires forward and work the bellcranks until the just start to rub a bit, don't be shy. That makes adjusting the rears unneccesary (since they already are at that point!). If the shoes are in too far, you may get really spongy, non-effective brakes. Easiest done with truck on stands of course.

Remember, the system only wants to move the parts like 1/8"....if the rears are out, you will get ODD results (I did!).

- adjust rear shoes
- check for vac leak
- try it. No go, bench bleed MC
- bleed everything
- No go - suspect MC or booster gone bad or out of adjustment.....