1993 4Runner Brake Problem

[skram]

I am trying to figure out what I am not doing correctly with my brake problem.
The breaks in my newly purchase 93 seemed to be fine for about 3 days. Out of the blue the pedal seemed to have more pressure in the high position than before. Also the breaks seemed to be working less and not stopping the truck as they had been doing. This progressively became worse and the vehicle was no longer safe to drive.
After inspection I discovered a leaks in both of the wheel cylinders. The pads on all 4 looked good to go so I went on to bleed the brakes.
Here's where it is getting tricky. I took it for a test run. The brake pedal felt high and not mushy but the brakes would barely stop the car no matter how hard I stood on them. I bled the rear brakes again and got some air out of one. My Wife may of had something to do with that? The other was fine. Still no brakes. I checked to see if the calipers were closing while off of the rotar and they did. I did not check to see if they would keep the wheel from spinning by hand. Either way, they won't stop the truck. Is there something electrical involved in this process.
I have seen posts where up to 40 pumps are needed. I didn't do nearly that many so that's where I will start next, but there was also mention of having the key in the on position but I think they were referring to 02 & 03 trucks.
Any help or direction would be greatly appreciated as currently I am lost.

Sorry this is so winded. Not quite sure how this all works yet as far as postings go.

 

[dem]

Nothing electrical involved and no need for the key to be in the ignition. Make sure that the bleeder hose is submerged in a jar of brake fluid and have your helper start pumping the brake, The helper should be in the down position on the brake when you close the bleeder valve. It took me approx 50 brake pushes only because i was flushing the old fluid out. If that does not work, I would say something is faulty with the brake master cylinder. Hope that helps.
Doug

 

[skram]

Thanks Doug.
Have you heard of this situation by any chance? High Pedal with pressure, but no brake? It makes sense that there is air in the line.
I will try the process again, this time with many more pushes to the break pedal. That may be where I am screwing up. I can go back an over analyze just about everything I've done and find some what if's.
Thanks for clearing up the Key/ingnition mystery and clarifing the process. I will let you know.

 

[skram]

When pumping the brakes up, the approx 40-50 times part, the bleeder should be closed, correct? I am just trying to build up the pressure at this point? Then open the bleed valve, and watch for bubles in the line. When the fluid stops, close the valve and start over with the 40+ times. Is this correct or am I missing something?

Mark

 

[dem]

Hi Mark
I have not heard of the situation you are describing.

As long as the bleeder hose ( vaccum hose works great and it tight) is submerged in the jar with brake fluid, you can leave the bleeder valve cracked open while the helper pumps, just make sure that the pumper stops in the down position, then you shut the bleeder valve.

I have owned a 1984 Toy 4wd, 1988 Toy 4runner, 1990 Toy 4runner and a 2002 Tacoma
I do all the work myself and I have never had any problems with the brake boosters. Only the Master cylinders and rear wheel leaking cylinders on my 84 toy 4wd. Let me know how that goes, I'm interested to know what you find.
Doug

 

[fourwd1]

A lot more info needed.
Does the truck have ABS?

You say you "discovered a leaks in both of the wheel cylinders. The pads on all 4 looked good to go so I went on to bleed the brakes."

That's conflicting, wheel cylinders are on drum brakes, pads are on disk brakes.
Which is it?

Have you bled all the brakes in the proper order ?? >>
LR
RR
RF
LF
LSPV

 

[dem]

Mark
I forgot to add, Make sure the master cylinder doesn't run dry or you will suck air back in...

 

[skram]

Thanks Guys, I changed the wheel cylinders on the drums in the rear. The pads on both the drums and the disks appeared to be fine. I have also kept an eye on the fluid level and added when needed. It has not dropped very low at any time.
In regards to the ABS system. I don't really know. I am slightly suspect of that because there is a wired plug coming off of the master cylinder.
When I originally bled the brakes, I started with the DR, PR, PF, DF. I later realized that I should have started at the farthest our 1st. Since then, I have bled the brakes in the rear 2 more times.
I am going to go and pick up the clear tubing today rather than just letting the brakes blow out on the garage floor.
What and where is the LSPV? Is this Left side purge valve? I haven't done anything with this.

 

[skram]

Last round of bleeding did not change anything. I still have high pedal and no brakes. I didn't see a purge valve on the master cylinder if it even has one.
We removed the vacuum line from the boost to see if anything was different. No feeling change in the pedal. Vacuum pressure felt to be good. However this time when I took the line off there was no audible pressure change sound.
What are the chances that I have a booster problem and what are some other ways of checking to make sure that's what it is?

Mark

 

[skram]

Brake Problem Solved.
Again to Dem, thanks for you help through the bleeding phase.
Turns out that the high pedal was for sure the Power Booster.
I put the new one in, started the car and presto. I have brakes again.
If anyone is having similar problems and want another opinion don't hestitate to shoot me a message. Maybe I can save you some examination time.

Thanks again,
Mark