Brake Problems...
 

Since I bought my new 97 4Runner, it has had problems with its brakes. Ive tried a few things to narrow down the possibilities of what is wrong. I've eliminated the rear brakes because I swapped my entire rear axle from another 4Runner with properly functioning brakes. After that I bled the brakes and it made no difference.

I then swapped the master cylinder from the same 4Runner with properly functioning brakes. The only thing I did not install was the paper gasket in between the master cylinder and the wall of the engine bay. I believe that is more to keep the metals from touching more than anything else. Although I did not bench bleed it, I bled each of connections coming out of it separately until there were no more air bubbles and clean brake fluid was flowing. After that, I bled the entire system and it was worse than when I started.

I also checked the flexible lines to see if they were "inflating" when the pedal was depressed and they were not as well as the entire system for signs of leaks.

As of now, when stepping on the brakes, the pedal will sink straight to the floor. If you pump it, the pedal will become harder to press, but there is still very little pressure applied to the brakes. I wouldn't rule out improper bleeding as one of the causes, but when I bled it the old fashioned way with a buddy, we bled close to a bottle and a half through the lines and continued pumping the pedal until well after we saw the last bubbles come out.

If anyone has any advice as to my next best course of action, it would be greatly appreciated.

I have a 1994 with the same problem I barely have brakes just enough to drive it. I've tried various brake booster, master cylinders, both front calipers, rear brake cylinders, and the rear rubber line. Since i've been trying to fix this I have gone through at least 6 big bottles of brake fluid trying different things and bleeding. The only thing I haven't tried yet are the 2 front rubber lines every part store out that sells the they are to short so I have to go through Toyota. When I replaced the rear rubber line my brakes did get better a little but not to what the truck was. Keep me up updated if anyone knows what might be the problem

Is it possible this I need a scan tool to cycle the ABS while bleeding? This weekend I'm going to put on Tundra brakes and properly bench bleed the master cylinder. If the brake pressure isn't fixed I might just break down and bring it to a shop

I dont have 4 wheel ABS on mine only the rear ABS. I've spoken to alot of mechanics and everyone is stumped on this one. i dont think it'd be any better with a ABS scan tool

Just found out my friend I was bleeding the brakes with removed the 2x4 I had under the brake pedal to keep it from going all the way to the floor. It was probably pumped at least a hundred times after that, and he said the front half of the reservoir went dry on one occasion.

Have the seals in the master cylinder gone bad after this amount of pumps on the pedal? I know I have to re-bleed the brakes because of the empty reservoir, but does the master cylinder need to be replaced considering the number of pedal pushes to the floor?

On that note does anyone know a source for brake master cylinder rebuild kits for the 3rd gen? Cant seem to find one.

well im good at brakes to fully eliminate the problem step 1 is you need to bleed the system with clean fresh fluid this mean putting the truck on jack stands pulling the wheels and using a power bleeder on the rears first then the fronts ok
if u still have a spongy pedal replace ur rear wheel cylinders and rebuild ur front wheel calipers and replace ur master cyl with a oem or nappa cyl not pep boys or autozone then bleed the system again if ur break hoses are ok to the the wheels no bloating then you technically should should be able to stop on a dime and get change back like my 91 is set up for mine stops like right now but you cant be cheap on the parts and expect it to preform breaks save ur life and ur bank acc !! it is also critical to know how to bench bleed a master cyl properly to get all of the air out before to hook up the lines
for 130$ you can buy the vacula bleeder its well worth it .