1. RDFTS

    RDFTS aka Rick Supporting Member

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    For the record I have had my master cylinder replaced on my raptor under warranty about 2 years ago.
     
  2. cayenne

    cayenne Full Access Member

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    I've had similar issues occur on a couple different vehicles. The only master cylinder that I had fail did produce problems like this but it was on a fastback Mustang long prior to ABS sensors.

    Cooked brake fluid does very weird things, I would change that first, it's too easy not to do as the process of elimination. I also had similar problems on another F150 in the late 90's and it was a wheel speed sensor. It was triggering the ABS system but never threw a code and never indicated ABS was having issues on the dash. Took me forever to track down, but the brake pedal behaved just like Noah is explaining. It felt like I would momentarily lose braking ability.
     
  3. The Car Stereo Company

    The Car Stereo Company aka nosbusa Supporting Vendor

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    so is a replacement better than replacing a seal?
     
  4. BenBB

    BenBB Full Access Member

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    Never seen a seal kit, master cylinder is around a hundred bucks with a new reservoir and cap so that's generally what everyone does. Bench bleed, swap it, then bleed at calipers...looks like you need to also bleed the ABS module: Post #3 in this thread from '09 calls for an NGS scan tool and "service bleed" at each corner. Can anyone verify this?
     
  5. J DAMAGE

    J DAMAGE Full Access Member

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    Haven’t looked up to see if there’s a rebuild kit, we just replace them, then use the scanner as in your post , scanner pretty much guides you through the rest, haven’t had to replace any of the abs, as of yet, that’s where it gets expensive.

    Back to square one, the problem is air in the system, being master cylinder, or internal leak in abs system, and yes dirty/contaminated fluid can cause problems.
    As stated by others, cheapest 1st step change fluid, then move on from there, but you are going to need scanner to do it right, because there is signs of air in system from what is being described, if there is hard codes, he should of popped a light, but if there is a soft code, no light, I would put it on a scanner to start, should see something.
     
    Last edited: Jul 12, 2018
  6. The Car Stereo Company

    The Car Stereo Company aka nosbusa Supporting Vendor

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    so i started with the easy one first. i changed the passenger rear caliper and bracket. it works to a certainn extent. coming down off the mountain that rotor was orange like the rest of them, but not as bright.the bracket pins were a little loose and the grease was pretty much toast. pedal still feels a little soft so i guess i look at the master cylinder next.
    @Hockster thanks for taking my call last sunday about my transmission. the filter change helped a lot. still overheats but i think a complete flush will solve it
     
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