1992 Ford F350 Dually Diesel Truck Brake System problem.

air in system push break down look for bleeder on check valve if not break line loose at check valve retighten . pump break don t fix push pedal loosen another line tighten back check again

sounds like you got air in the system, when you replaced the master cylinder, you need to bleed it all out takes a lot of fluid to go through the system to get all air out

I have the same problem,, put all new brake components on truck, needed it anyway,, found out that the booster is not designed for a diesel application,, ford made a model change for the diesel,, number from ford is F 5 T Z - 2005 CA a zero loss booster,, have ordered on will put on when arrives, $240. good luck,,

BY TRUCK HAVING ABS BRAKE.YOU NEED A SCANNER TO BLEED BRAKES THE SCANNER HAS TO RESET OPERATION OF THE BRAKE HYDRALIC SYTEM BEFORE YOU CAN BLEED SYSTEM.

You need to crawl under the truck and inspect each brake line for leaks. You also need to check wheel cylinders and calipers. The chances are pretty good that you will find a small leak in a line or a wheel cylinder leaking, pay close attention to the rear of the truck because that is normally where these problems occur. Hope this helps.

when you replace the master cylinder, your are supposed to pump it up manually before you install it. If you don't, you'll have to sit there and pump the brake pedal a couple of thousand times as one almost microscopic air bubble at a time escapes the pressure tube and back fills with fluid. once you can push the pedal repeatedly without any bubbles escaping into the reservoir, then bleed the brakes. Starting with the farthest, usually the Right Rear and work your way up. Make sure you keep the fluid level topped off. If it sucks air once, you have to start all over.

possibly new master cylinder is defective

Perfect well at this point i would say that tha abs valve is bypassing fluid. If you can un hook the line that comes into the abs valve and plug it and try and bleed the system where you cap the line going into the abs valve. If you get a good pedal after pluging the line going into the abs valve this tells me that the abs valve is bypassing fluid give it a try i have ran into this a few time and the abs valve has been bad. Also can you rate this sluton also i do hits on my own free time thanks good luck

5 Inspect Brake Fluid Type Brake fluid loss or contamination 10 Inspect Master Cylinder (Brake System) Worn or leaking brake master cylinder. 11 Inspect Brake Power Booster Damaged booster vacuum line/check valve, or diaphram

With no leaks and a little braking action returning by pumping the pedal I would suggest looking into a master cylinder. Low brake fluid level in the master cylinder will cause the brake warning light to illuminate (possibly, also the ABS light).

If the truck has the 7.3L diesel, it will have a vacuum pump which supplies vacuum for all vacuum accessories. I believe if the vacuum level drops below 10 in. of Hg, the brake light will illuminate. If the vacuum pump fails you'll know it as the brake pedal will require quite a bit of effort to effect any braking effort.