No brakes on K3500

[RaptorMan555]

Hope someone can help me on this one. I'm


Hope someone can help me on this one. I can't get any brakes on my 1 ton 4x4 project. I've gravity bled the front and no pedal at all. Replaced the master cylinder twice just in case. The hydraboost is good. Any suggestions?


1982 1/2 ton 4x4 6.2 Banks Turbo
1980 1 ton 4x4 6.2 Banks Turbo
1992 3/4 ton 6.5
1992 1 ton 6.5
1975 7500 GMC 6V43 Detroit

[Brianlar]

I had better luck pumping the pedal with a helper turning the bleeders. Trick is, get em to stop your pedal travel by tightening the screw while you are depressing the pedal after the air is gone. Check the rear brake adjusters? Got antilock? good luck!

[dieselbegreat]

Master cylinders must usually be bled before they are installed and connected to the hard lines, and gravity bleeding the front brakes is not good enough to get a firm pedal. I would buy a couple quarts of brake fluid and, with a someone's help, flush the entire system per the service manual. (It's a long way to the back wheels.) Some ABS requires special procedures to bleed the system.

[wvo]

I don't know if this applies to your vehicle, but my '82 3/4 ton suburban has a brass valve that the lines from the master cylinder go down to. As I understand it, if my front or rear portion of the system develops a leak then the valve isolates the leak and allows the other portion of the system to still develop pressure. The valve has a piston inside that can hang up. I think if the piston is not centered then the brake light comes on in the dash. It gave me a bleeding headache until I figured it out.

maybe