Brake Booster? interactive vehicle dynamics (IVD)

Lincoln LS

  1. jinx8402

    jinx8402 Active LVC Member

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    Hey Guys,

    Sorry in advance if this has been covered...but I have searched here, and also by using Google to search this site since sometimes it finds things that the built in search does not find...

    I am having a mushy brake pedal, and notice that when I press the pedal all the way down to the floor and release it makes a noticeable hiss noise. From searching it seems like a brake booster/vacuum leak issue. I looked up and found there are two brake boosters for our cars. One with IVD (interactive vehicle dynamics) and one without. How would I be able to tell which one I would need?

    Also, I have heard sometimes it's the vacuum line and/or a plastic pvc like piece that could cause the issue. If any one has any input on what/where I should look for, let me know. Hoping it's that rather than the booster itself.

    Thanks!
    Craig
     
  2. joegr

    joegr Dedicated LVC Member

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    Some hiss is normal.
    Mushy pedal is often caused be air in the brake lines and/or old (contaminated) break fluid. Have you tried bleeding them?

    Do you have Advancetrac (not to be confused with just traction control)? If so, then you would need the IVD booster.
     
  3. jinx8402

    jinx8402 Active LVC Member

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    Well, I just had my rear rotors/pads/calipers/hoses replaced. My mechanic did them. He said the front hoses were good. He changed the fluid/bled the system a few times because he noticed the mushy pedals as well.

    He has an extremely busy shop, and wasn't able to diagnose further at that point as it was the end of day on a friday. This was two Fridays ago. He wanted me to give it a few weeks to see if it would (for lack of a better term) normalize. It hasn't as of yet. Was just seeing if it is something relatively easy that I could take a crack at.

    I don't believe I have advancedtrac, just the normal traction control that I am aware of. I have a non-sport V8.
     
  4. LLADNAR

    LLADNAR LVC Member

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    To know if you have Advance Trac is just knowing what the symbol looks like. Advance trac has the car with the squiggly lines behind it and Traction control is the tire and wheel peeling out. Also it does sound like your booster is hissing. The seals go bad in them sometimes.
     
  5. jinx8402

    jinx8402 Active LVC Member

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    Thanks. I'm fairly handy, but haven't replaced a brake booster before. Anyone have any steps to replace? Can just the seal be replaced?
     
  6. LLADNAR

    LLADNAR LVC Member

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    No you cant replace the seals. They are not rebuildable. Never replaced a booster on an LS. Have on plenty of other Fords as a Dealership tech. But since Lincolns have a badass warranty we usually ship them to our sister dealer to have that stuff fixed. That being said, it doesnt look fun
     
  7. jinx8402

    jinx8402 Active LVC Member

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    Yeah, I am going to look at the hose and valve check first to see if that's the issue. Perhaps one of them is damaged causing the leak.
     
  8. dlo73

    dlo73 Active LVC Member

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    I just changed my booster and abs module, it had to be programmed so I didn't do it myself.
    with brakes I feel better let a pro do it.
     
  9. dirtydeedsdonewithsheep

    dirtydeedsdonewithsheep New LVC Member

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    ok so i also need to replace my brake booster. I am 99 percent sure it has gone bad. The member above said it has to be programmed? what do you mean by this?
     
  10. joegr

    joegr Dedicated LVC Member

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    The ABS module had to be programmed. If you're not swapping that, then you don't have to deal with it. There is a sensor under the dash that you may have to replace.
     
  11. dirtydeedsdonewithsheep

    dirtydeedsdonewithsheep New LVC Member

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    ok. so i replaced the brake booster. which is not not fun. but i got it on there and im still having brake problems. instead of the brake pedal being mushy, it is hard now like it should be, but i have hardly any stopping power, like i just have manual brakes. The master cylinder has been replaced as well. i hear a hissing noise which i assume is a vacuum leak, but when i press on the brake pedal it stops. any ideas?
     
  12. LS4me

    LS4me Dedicated LVC Member

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    Did you bleed the system; correctly? When I installed the SS lines I had to have the engine running to properly bleed the lines.
     
  13. joegr

    joegr Dedicated LVC Member

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    Did you use a new booster? Or a used one that might be defective?

    A vacuum leak will prevent you from getting much or any boost. This will make a pedal very hard to push. Note that you may still have the "mushy" problem too. There's no way to know without the booster working.
     
  14. joegr

    joegr Dedicated LVC Member

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    If the booster isn't working (due to the leak) having the engine running or not while bleeding wouldn't make any difference.
     
  15. LS4me

    LS4me Dedicated LVC Member

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    True. I was just "questioning" the bleed. My pedal makes a hissing type noise when I depress it too. Always has. On all my Ford products. Heard only from inside though.
     
  16. joegr

    joegr Dedicated LVC Member

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    Yes, that's normal. I think that he is saying he has a hissing noise all the time when the engine is running, and it stops when the brake pedal is depressed.

    Normally, there is vacuum on both sides of the diaphragm inside the booster. When you press on the brake pedal, air is allowed into the side of the diaphragm facing you. This air can now push against the diaphragm (the other side is still at vacuum) to help you push the brakes.
     
  17. dirtydeedsdonewithsheep

    dirtydeedsdonewithsheep New LVC Member

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    yes i was saying is the hissing is constant untill i press the brake pedal and it is silent. I will take you back to the beginning of my brake problems: A few months ago I noticed that the brakes were getting weaker and weaker. I took it to mechanic friend of mine who noticed that the master cylinder was leaking. apparently it had been leaking for awhile because you could see where brake fluid had been running down the brake booster. So we changed the master cylinder and bled the brakes with the car off (not sure if this should have been done with the engine on or not), but when i started driving it again immediately afterwards, i noticed a considerable hissing noise which would stop when the brake pedal was pressed. So we assumed it was the brake booster. So a couple weeks later we changed the brake booster. The old brake booster WAS damaged because when we pulled it out, we noticed that the whole inside of it where the master cylinder goes in fell apart. So we replaced the brake booster and the brake pedal is hard now, but it harder to stop now then before we changed the booster, and i still hear the vacuum leak, which sounds like it is coming from down near the brake pedal. The booster was a brand new motor craft booster, and the master cylinder was brand new as well. We did not loosen the brake lines and ive been told that its not necessary to bleed the brakes when changing the booster if the lines are not loosened. Even if the brakes need to be bled, i dont know what would be causing the vacuum leak. Its like Im getting now power from the booster. Very frustrating and i dont know what to do!
     
  18. TooManyToys

    TooManyToys Well-Known LVC Member

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    I think you got a bad booster. Without application there should be no air movement (hiss). With application the reaction valve allows normal air into the drivers side of the booster to essentially pressurize that side of the diaphragm(s) for assist. Most likely the reaction valve is assembled incorrectly.

    Bleeding the hydraulics has nothing to do with the booster side of the application system. If you can move the M/C out of the way during a booster replacement, the hydraulics will not need to be bleed as there would be no way to get air into the wet side unless you flip the M/C upside down.

    The brake hydraulics on this vehicle like any other can be bleed without the engine running.
     
  19. dirtydeedsdonewithsheep

    dirtydeedsdonewithsheep New LVC Member

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    ok. i will look into it. thank you all for all your help. i hope thats it, cause this has been frustrating.
     
  20. LS4me

    LS4me Dedicated LVC Member

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    Tried it on both the '00 & '06 and we couldn't get the system to push fluid unless the engine was running. We were using the two-person method without a fancy-shmancy machine.
     
  21. TooManyToys

    TooManyToys Well-Known LVC Member

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    We never had an issue with our test LS, and I didn't with my wife's car ??????

    Maybe it only works on this side of the country.
     
  22. joegr

    joegr Dedicated LVC Member

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    I haven't had any problems with my 04 or 06 when bleeding with the engine off. I put a clear hose over the bleeder and put the other end of the hose in a bottle. (This to keep air from being sucked back in.) I bleed by pushing the brake pedal, with the engine off. It's easy, and I do it enough to change out all the fluid.
     

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