Why doed the brake pedal fade on f350?

Answer 1

There are many reasons you may experience brake fade.

Here are some possible causes,

1. Contaminated brake fluid.
2. Internal leak in the master cylinder.
3. Internal leak in the ABS unit.
4. External leak in the system.
5. excessive heat build up in the system.

The modern braking system has become more complex. These ABS systems seem to

allow more "flex" in the hydraulic system allowing more pedal fade.

The three pump test,

It has been a standard for years to test the brake system for Master cylinder by pass. I have tested many newer Fords and they on the most part fail that test. I have been told officially that this type of brake pedal fade is common for this brand and is not an issue.

If you experience brake fade during operation I strongly recommend getting it serviced including having a brake fluid test and flush if necessary. most foreign auto makers require a brake fluid flush every 30,000 to 50,000 mi as a part of their maintenance schedule, the big three do not.