Expedition. Brake Fade. Not fixed with new Brake Master Cyl

[Rhasmas]

Yes my ABS light came on the other day on my Ford when i was driving and then went off. Ever since i went to drive my truck i put my foot on the brake and she is grinding and jumping and i can feel it in the wheel. When i am driving she is fine but when i go to put my foot on the brake she is jumping and has a grinding sound . What would make her do that? I am afraid to drive her.

[Karl]

Sounds like you just have a base brake problem. The grinding is most likely caused by the pads being worn all the way down to the rotor, and now you are driving "metal on metal".
No, i would not drive it.

The sound and feeling means your brakes are grinding away !

This would also cause the ABS light.

It may be that you have a caliper that locked up, or they just plain are worn out and have not been check in a long time.

[ExpeditionGuy]

Expedition, yr=2000, 5.4L, 4x4 auto, 110k miles, Cruise control, Vehicle location is Northern California wine country.

Brake Fade. Truck normally driven each day. Parked 2 weeks (I don't know if this has anything to do with the problem). Symptom. When braking at a constant pressure the pedal fades to the floor. If I press more quickly, I get more braking. I had the brake master cylinder replaced with a new OEM spec'd part. Same problem. Another new brake master and the symptoms remain. There is zero fluid leaking anywhere.

It seems like there is a valve that is allowing fluid to pass back and not out to the calipers. This leakage seems to be a specific volume as there is a particular rate which I can press the pedal and it goes steadly to the floor with no change in braking force. I press a bit faster and I get braking force but not 100% of the force prior to this problem.

Thanks. ExpeditionGuy

[carriedi]

if the master cylinder is not the problem and there is no fluid loss (leaking) and the brake hoses are all in good condition, you should look at your ABS. the electro-hydraulic unit could be bad.

can you get the pedal to fade with the engine not running? with the key off, pump the brake pedal until the pedal if hard and won't go down with vacuum asist. then try and make the pedal fade. if you cannot make it fade, hold the pedal down very hard. start the engine. the vacuum booster should let the pedal go down. do you get the fading pedal now? If you do, take your foot off the brake. then Brake again and put the truck in gear. push the brake pedal until it fades all the way down. does the truck start to roll? If the truck doesn't start to roll let the brake pedal up slowly. where on the pedal does the truck start to roll at? Just off the floor or does it stay in place until you are 1/2 to 3/4 back to the top? If your truck starts to roll right from the bottom you should look to make sure the master is good (anyone can have a bad new part) then look at you abs unit. If the truck doesn't roll until you are back up near the top of the pedal then you might not have pedal fade. Your booster may let you push the pedal close to the floor but where it activates and releases the brakes is where you see if the brake hydraulics is the problem.

[Djk6211]

When the clutch pedal is depressed the brake pedal depressed a bit causing slight braking when shifting. Help please?

[carriedi]

that's might be a tough repair unless you are patient and focused. The shaft the goes through the brake and clutch pedal can get rusted up and bind the pedals together. If you are lucky you can spray some kind of lubricant up to the pedals and it will be okay. Most times you have to remove the shaft and manually clean and lube the parts up. It's not hard but there are a lot of things that you have to take off to get at the shaft bolt and get it out of the vehicle to take it all apart.

[Djk6211]

Thank you. I thought this may be be problem. I recently found out the truck had been sitting for a while with a broken driver side window. It was tarped but moisture had been an issue. Thanks for your help.

[Djk6211]

What would cause the engine to rev up when brake pedal is released? It is only for a couple of seconds then goes back to normal RPM. Vacuum issue?

[carriedi]

I think I would look at what the vacuum is doing there. Try pinching off the vacuum booster's vacuum line and pump the brakes and see if it still does it. (while you are in park. don't go driving like that. It will make it hard to stop)