Hard Brakes - Mystery!

[BamaDrewski]

First off, I have searched lots of the forums and posts for a possible solution. Finding none, I am posting here.

Problem:

Brakes started failing over a period of two days. At first, they were a little hard but once the engine warmed up – they were fine.

NOW, the brakes are as hard as a rock.

This is what has been done:

1. Master cylinder installed
2. Brake Booster has been installed (Salvage yard)
3. Brakes have been bled in the proper order.
4. Wheel cylinders on rear have been replaced.
5. Vacuum hose from manifold to booster has been replaced.

The brakes are still hard as a rock.

Any suggestions?

 

[nissanh]

Did you get the one-way valve in vacuum line between the manifold and the booster in the proper direction?

Do you have another car? if so, can you run a hose from that car's brake booster (from
intake manifold) to the 4runner booster? would this soften the brake?

Is the masterpump is clogged? or the lines running from the master pump to wheels are clogged?

 

[BamaDrewski]

Did you get the one-way valve in vacuum line between the manifold and the booster in the proper direction?

Do you have another car? if so, can you run a hose from that car's brake booster (from
intake manifold) to the 4runner booster? would this soften the brake?

Is the masterpump is clogged? or the lines running from the master pump to wheels are clogged?

Thanks for the suggestions. I am not sure what you mean by "master pump" unless you are referencing the Master Cylinder.

The lines are clear. I have bled the brakes. There was an issue with the rear brake cylinders and I replaced them. (Yet, still the same issue) The brake fluid flows freely now to all four wheels.

I had not thought of connecting the booster to another vacuum source. I may try that!

 

[LittleCaesar]

You replaced the check valve too correct? Grommet as well?

 

[nissanh]

Yes, I meant the master cylinder.

How many inches does the paddle travel to a complete stop? When pressing it, does it feel like soft and all of a sudden it is hard and no more travel? At this level of the paddle, do you feel the truck's wheels are not locked?