1997 Ford F-150 Spongy Brake Pedal

FORD F-150
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LLCF-150
  • MEMBER
  • 2 POSTS
I own a 97 f-150 4x4,4.6 liter with 4wabs.
Problem is a soft brake pedal and extra effort to brake at any speed.
Replaced master cylinder.power booster check valve,
both front calipers,hose's,pads and installed sloted front rotors and replaced rear shoe's and hardware.
Problem started after last summer from a vacation trip. Bleed brakes 6 times and used 2 quarts of brake fluid.Also checked push rod at booster,okay.
Brake pedal has 2" travel with engine off,3" when engine running.
What could be the cause? brake booster or
4wabs unit?
Any help would be great!
llcf-150 :?
Apr 25, 2006 at 2:55 AM
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LOSONE
  • ✓Experienced Mechanic
  • 1,616 POSTS
It sound slike you may have air trapped in the upper part of the Anti lock hydraulic module. Try bleeding it but start from the top lines.

DON'T pump and hold on a Ford system. Have someone inside the truck hold the pedal, you loosen the bleeder. Keep the pedal down until you tighten the bleeder then release the pedal. Repeat until there are no bubbles or foam like brake fluid.
Apr 25, 2006 at 4:08 AM
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Suggested Repair

Bleed the anti-lock hydraulic module starting at the top lines. Have a helper hold the pedal down, loosen the bleeder, keep the pedal down until the bleeder is tightened, then release the pedal. Repeat until there are no bubbles or foamy fluid. Do not pump and hold the pedal on this Ford system.

Conversation Summary

The owner of a 1997 Ford F-150 4x4 with 4WABS reports a soft brake pedal and extra braking effort that began after a trip. The master cylinder, booster check valve, front calipers, hoses, pads, slotted rotors, and rear shoes and hardware were replaced, and the brakes were bled repeatedly. The expert suspects air trapped in the upper part of the ABS hydraulic module and recommends bleeding from the top lines using a hold-down method rather than pumping the pedal.

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