nolan5121

94 4runner 3.0 144k on the odometer.

After bleeding the brakes and bleeding the brakes and bleeding the brakes. I put about 4 quarts clean brake fluid through the system. There was no air in the system. As soon as I start the truck up the push the brakes in and bleed them again there is significant air in the brake system at each corner. I suspected the master cylinder was bad. So i replaced that. Its still doing the exact same thing. After bleeding the brakes and cranking the truck the pedal goes down about 3/4 of the way to the floor. It still stops the vehicle but the air in the lines needs to be fixed. I cant find anything on the internet that has these problems.

The only idea that I have now is there is a bad connection somewhere. My brother bought this truck about 6 months ago and I think it has been like this since he bought it.

Any ideas on what is wrong or how to find the culprit...

Thanks

James Woods

iTrader: (1)

Did you bench bleed the master cylinder when you replaced it? When I bleed brakes, I always let the calipers gravity bleed after using my vacula before I close the bleeders. Also make sure that the rear wheel cylinders are not leaking and letting in air, they are a PITA sometimes.

82greenbeast

x2, I've run into this before of past yota's, times i thought for sure air didn't get into the master cylinder.. It did. If you did that, I'd take a second look at the flex lines, bumped into that before too.

Nailit69

I just did new calipers on my 94 runner. First, make sure you have the bleed valves up/on top and not down. I mounted mine, took a tube from the bleed valve into a jar of fluid and pumped em about 8-10 times (make sure the bubbles and foamy goodness stop) and now they'll launch you through the windshield. No need to close the valve off after every cycle, just make sure the M/C stays full and the hose stays in the fluid till you're done w/each one. I always start w/the farthest one from the M/C (RR/LR/RF/LF). It took me about 7 minutes to flush & bleed out my entire system.

(Side Note) The parts are pretty cheap, usually i'll just replace pads, rotors, calipers, wheel cylinders, etc., while im in there. There's less than $400 in parts in the entire process, why not just buy all new?

EFI85

all cars with power brakes do that upon start up . its the vacuum assist pulling the pedal down . If thats not it id check the adjustment of the rear drums . if that doesnt make the pedal feel better then get a dead blow hammer and bang on the calipers while someone pumps up the brakes . Some time a bubble will get caught in the calipers .

nolan5121

Thanks for the help so far.


I did bleed the master cylinder back into it self prior to bleeding the brakes in order of RR, LR, LF, RF. Like I said all the air was out, then as soon as you start it and push the brakes air gets into the lines. There is no noticable leak anywhere, specifically there is not a noticable leak in the rear wheel cylinders. I looked at that and the brake dust was relitivly undisturbed around the wheel cylinders. What I think is happening is there is a small pin hole leak somewhere that fluid is not coming out of but air is getting sucked back into when the brake pedal is being let go of. I dont really want to spend 400 dollars rebuilding the breaks ( I nor my brother has that extra money laying around). Any Ideas on how to isolate this to fiqure out where the air is getting into?

cubuff4runner

Does it have ABS? I am not too familiar with 2nd gens, but I did have air get in my 3rd gen abs actuator once and it wasn't coming out, but I no longer was using my abs so I just removed it.

topdog63

Check all of your fittings and make sure they are tight. Make sure the rear brakes are adjusted properly. Pull the dust boots back on the wheel cylinders because sometimes they will leak but the boot will hold the fluid in. You can always open all the bleeder valves and just let them gravity bleed, just make sure the master doesn't run dry. Also check all of your brake lines carefully because if theres a hole letting air in, it's going to let fluid out when you push on the brakes.

Another thought, if the previous owner put something besides brake fluid , (i.e. transmission fluid) in the master cylinder, you will have to replace the calipers, wheel cylinders, master cylinder and all of the rubber hoses. Brake fluid is a water soluble product and if someone put a petroleum based product like ATF, motor oil, PS fluid hydraulic fluid, it will ruin all of the rubber seals. I used to be a brake and suspension mechanic and I saw this almost everyday.

topdog63

One other thought, are you still getting air when you bleed the brakes or does the pedal just feel spongy?

nolan5121

I am getting air in the brake lines after I have bled the brakes.

If the rubber seals were ruined would it not be leaking somewhere? I have been at each wheel and have not seen any leaks.

This 4runner to my knowledge (which is very limited) does not have ABS.

I am going to trace the lines back and tighten as I go and see if there is anything that looks amiss when I get off work. If that does not work I am thinking of getting some caps and start isolating the break lines to 1 wheel at a time and see if I can get the problem to go away at a wheel. Then try and fiqure is out from there.

topdog63

If you find that everything is tight and you don't find any cracks in any of the lines try bleeding the entire system. By that I mean bleed everything separately. Go to every place that a hose hooks together or into something else and crack of open with someone pushing on the pedal. That should get any trapped air out

ksti

I was wondering if you did a recent brake job or did your pedel just start going to the floor and you just decided to bleed the brakes?

angrybob

X2 - Why did you bleed the brakes?

Did you include the LSPV when you bled the brakes? If not, there are many, many threads on this topic. Do a quick search on "LSPV" in this forum.

topdog63

If I read it correctly, he bled the brakes because it has had a spongy pedal since his brother purchased it and they were trying to fix it.

nolan5121

So I got (4) M10x1.0 male to male unions. I took the bleeder screw out of the wheel cylinders and calibers to test the calibers to the master cylinder to check if the leak was in there or the caliber. During this expedition I found out that the connector on the right front would not tighten up onto the union and after tighten it was leaking. The leak when on the caliper was minimal enough that I could not see the fluid and (that coupled with the boots on the half cv axle were torn and there was grease everywhere). Well you could see fluid but I thought it was from the grease. SOOO. since the stores are closed I will pick up the part tomorrow after work and bleed again.

So to answer a couple of the last questions. the brakes are good(enough pad), just the brake fluid was not. since my brother bought this truck I have been helping him go through and fix what is wrong and changing fluids. I don't think the fluid had ever been changed in this truck it was nasty. Plus its an excuse to use my car lift

Ill update tomorrow night on the results.

THANKS so much for all the responses. If it was not for this site and others like it (other vehicles) I dont think I would have the courage to do a lot of the work my self.

you guys have a wealth of knowledge on this site and thanks for sharing it.

Nolan

nolan5121

So its fixed now, bad connection in 2 of the lines that was leaking fluid slow enough to not drip anywhere and letting air in. Thanks for all the help.

Nolan

abecedarian

4 quarts of brake fluid? Really? Did you mean "pints"- the small bottles?
I did a complete flush on my '88 4Runner and didn't use much more than a quart.

Anyhow, glad you got it fixed.

nolan5121

abe- I wish i meant pints. no I put 4 quarts through the brakes trying to get all the air out. Finally found the culprit though.

scroungecat

have you tried your check valve for your power booster

SR25JD

I Back Bled Each Fitting,Was Able To Get All Air Out...Hope This Helps,Had To This On My Ol 55 Pan Head To Remove All Air From Lines,Also Did This Little Tip On A Ol Chevy......Works Great.