04 4Runner Master Cylinder???

[cgarrett5119]

2004 Toyota 4Runner 4WD 4.0L V6

Got a question... my wife's 4Runner needed the front pads changed. Took them to a shop to have them replaced. She got the car back and when I drove it on the weekend the brake went nearly to the floor before engaging in the last 1/4 of the stroke. I had her go back to have them bleed the brakes again assuming air was in the system and nothing was wrong with the brakes before the pads were replaced.

Long story short, they rebled, the issue did not get resolved. I took it to another shop to see what they thought, they bled them twice, no change and now they are saying its a master cylinder is shot. In my mind there is no chance the master cylinder being bad considering it was entirely fine before the pads were replaced.

Is there something the shops don't know about bleeding this system? Thoughts and comments are welcomed.

This is my first post on this forum. I usually go straight to the forums whenever I have an issue with any of my vehicles or toys. Loaded with information and knowledgable people so thank you in advance.

 

[audiness]

2 thoughts:

1. the shop accidentally let the cylinder run dry, and there is air trapped somewhere in the master cylinder. i read somewhere if you let it go dry, you have to have toyota hook it up to a computer to cycle all the gizmos inside it to fully re-bleed it.

2. I recently bled my brakes, and found that trying to bleed with the car turned off didn't work very well. I had to have the engine running, there seems to be some sort of pump in teh master cyl that wouldn't come on w/o the car being on.

 

[DocMT]

Yes, if air gets into the master cylinder, you have to go to a Toyota dealership so they can hook up their scan tool and re-bleed the entire brake system. Both the Chilton and Haynes manuals warn against getting air into the master cylinder for this very reason.