2003 Ford F-150 with caliper brakes on the front and back.

Here is what I have done so far:
1) Checked for external leads at brake calipers and Master Brake cylinder. No leaks
2) Replaced Master Cylinder and used a bleed kit to bleed the Master Brake Cylinder on the vehicle.
3) Replace the back pads. They were thinner than the front, so I replaced them. Didn't replace the front pads. All caliper boots and cylinders no leaking an in good condition.
4) So far have bled system 3 times with a vacuum hand pump.
5) Brake Pedal is still drifting to the floor.

What's left?

This vehicle has 463,00 miles on it. All calipers are original. Worn calipers, maybe?

Thanks

 

Not an expert and I don't know the fine details of what exactly happens but I've read that the ABS pump can cause that. Bad seals in the pump. Might be worth researching. If the MC is good then the fluid has to be going somewhere.

 

Here's a video with what look like some good simple easy tests. One for the MC too. Today's aftermarket parts can be bad out of the box.

 

The HCU for the ABS brakes is what's left
It can bleed brake pressure down
Very few and far between failures like that from an HCU though
I would verify and verify then re-verify the master cylinder bleed
4 wheel ABS HCU replacement is north of 3500 bucks so put at least two master cylinders on it

 

You have put 5000 psi in all 4 brake lines with all 4 wheels off? (testing 1-2) (testing, testing)
I use a basic brake pedal depressor tool against the seat
Then a good visual inspection
Bleeding with a vacuum pump is not the way pros do it
Use your foot and an assistant (gravity bleed first)
Build some pressure before loosening the bleed screw
Do that 5 more times starting with the longest brake line
Usually the RR
Good luck

 

By testing valve body as shown in the video, the plunger inside the valve body is leaking oil back into the body.

Bad ABS Pump/Valve Body.

Has anyone rebuilt one of these Valve Bodies and Seals?

 

Looks like a reman valve body is around 250 ish on rock auto.

have you considered something from a auto recycle yard, and just swapping it out?

 

It's the HCU. I have a 2003 and mechanic replaced 2 Master cylinders that did not fix it. Replaced HCU fixed it.

 

Just wanted to let everyone know that the problem was with the ABS Anti-Lock Brake Pump Valve. The module was fine, but the pump was bad. A new one from the Ford dealership is around $1000 brand new. Not what I spent though. I got on FB market place and there were several F-150's in my year being parted out. I bought one for $50. Works fine! Brakes are as good as new.

 

https://www.ford-trucks.com/forums/1...ke-issues.html