Ok I bought an 88 4runner a few weeks ago. Brakes were a little spongy so i figured I would spend the money and replace pretty much everything since the majority looked original.
Did the rear last week, replaced shoes, springs wheels cylinders and brake lines going into the wheel cylinders, blead everything. After that when first hitting the brakes there was almost no pedal, but after 2nd pump brakes were fine.
Today were replaced the fronts, new rotors, loaded calipers etc. Just as we were finishing bleeding the rear brake line off the proportioning/distribution valve busted. (two that run along the frame by fuel tank). Replaced and bleed again, the rear brakes were locking up, and/or had no fronts. Then we replaced the master cylinder and now theres no pedal at all.
Our only thoughts is that the lines are air locked somewhere and the system won't bleed. Anybody run into anything similar? Have any suggestions or solutions? I guess tomorrow we're going to try and use a vacuum pump and see if we can get fluid through the lines. Appreciate any input that could be given.
Thanks
Jason

 

are u using a vacuum bleeder?

 

No we didnt, we just did it manually using the brake pedal. vaccum pump/bleeder was next thought.

 

the mighty vac hand held pumps are nice

 

I have the same problem with my 88 4Runner. Did all the same work you talked about. The problem with is the Brake Booster. Mine doesn't stay pressurized. If I pump my pedal to pressurized the booster my brakes work great. Havn't swapped it out yet. No cash.

 

bench bleed the master cylinder. you can't bleed the air out of the master cylinder any other way unless extremely lucky. you can do it while installed on the truck but probably easier to remove it. do a search to understand the process if you aren't familliar.

 

We did bench bleed the master before we installed the new one, and we tried again while it was on the vehicle. I think we got all the air out of the master, unless i got a bad one, or damaged it while trying to bleed the air out of the system.

 

update: We used a vacuum pump and that pretty much took care of it. Bleed it at all point with that and then went through and pedal bleed it and the brakes are much better. My pedal is just as rhah mentioned, pedals a little soft to start, a few pumps and its hard and brakes are great, i guess a booster is somewhere in my future also. Thanks for the help.

 

Before you decide to replace your booster take a look at your Check Valve, it's located mid way on the vacum line going to your booster. It's a simple check that will only cost a couple bucks it thats the problem.

 

Does anyone have anymore information on the check valve? I tried searching but didnt really find anything more. My brakes were good, little bit of a soft pedal on first pump, fine afterwards for about the last 1500 miles or so. I was diriving it the last 2 days and this morning on the way to work there was almost no pedal first pump and after that it was fine. Didn't really have a chance to look at it being at work now. Is the booster shot??? I know theres a way to check it in the fsm I'll check when i get home. I also want to check/replace the vacuum hoses. Just curious if anyone else has anything to say. Thanks

 

You said you replaced the rear brake shoes etc.
Did you adjust the brakes up in the rear? If not thats a good chance why . The first time you step on the brake the wheel cylinders don't quite travel enough to apply the shoes, when you pump them it makes the cylinders push the shoes out more to the drums.
Just a thought. seen alot of people do that and wonder why they have to pump the brake pedal.
Good luck.

 

The check valve won't cause your symptoms (unless it's sticking closed, maybe). It holds vacuum in the booster after you shut the engine off, so that you have a bit of power assist left even if your engine stalls while you're driving.

 

As far as with the rear shoes I beleive everything is adjusted correctly.

I tried testing the booster as the fsm explains to check for operating and air pressure and atleast from my interpration what the fsm states everything tests good. The vaccum line looks good, and there is an obvious difference if I pull it off, so i'm assuming that good. The brakes still seem to function properly, it's just the pedal goes pretty much to the floor on first pump. Its snowing and getting dark out so I can't really check much more tonight. The only thing I did in the last few days was top off the brake fluid (possibly overfilled it) I wouldnt expect that to do anything but i might be wrong. Thanks for the input so far.

 

Really sounds to me like the shoes are not adjusted properly or you still have air in the system

 

Reading back over your post the shoe adjustment makes sense for what its doing. I'll start there and see what happens. Thanks

 

Okay I got some brake problems myself and I can't figure out how to post it... email me please. I don't know how to post... Anyone! Thanks. Pedram@webcitypages.com And I don't know where to check for replies if I did post. I'm new. (begging) Thanks again.

 

I am haveing the same problem you are haveing change front wheel bearings and pulled calipers do so, also I was leaking brake fluid between the master cyl and booster so I replaced master cylinder and bench bleed it and cant bleed out the rest of the system, never seen a system that wouldnt bleed any ideas, bleeding manually... Thanks

 

Need more details to help you... especially about what vehicle you're driving.

 

i hate to say it... but try bringing it to pepboys for a bleeding, its like 35 bucks (atleast it was the last time I had them do it, ~7 years ago, lol).


I tried and tried and tried to bleed my brakes properly on my ex-camaro, no matter what I did... I couldn't get all the air out.

Pepboys hooked up a machine to my vehicle, let it 'auto bleed' for about 15 minutes, i paid my 35 bucks, and the brakes felt brand new afterwards.

 

Update: just called pep boys for bleeding, they charge 59.99 to do a complete flush and brake adjustment....