1. Welcome to Jeeps.net!

    You are currently viewing as a guest! To get full-access, you need to register for a FREE account.

    As a registered member, you’ll be able to:
    • Participate in all Jeep discussion topics
    • Transfer over your build thread from a different forum to this one
    • Communicate privately with other Jeep owners from around the world
    • Post your own photos in our Members Gallery
    • Access all special features of the site

Little vacuum / hard breaks

Discussion in 'Liberty' started by aidanmoffatt, Feb 21, 2019.

  1. Feb 21, 2019 at 11:42 AM
    #1
    aidanmoffatt

    aidanmoffatt [OP] Jeep novice

    Joined:
    Feb 19, 2019
    Member:
    #2905
    Messages:
    12
    Gender:
    Male
    First Name:
    Aidan
    Cornwall, England
    Vehicle:
    2004 Jeep Cherokee (Liberty) 2.5 CRD Limited KJ
    Hi all, I’ve had some braking issues, and from what I can see it’s quite a common fault. I originally suspected the booster as the issue but noticed the vacuum (when disconnecting the heater line) was very poor. So I then thought vacuum pump... Today the vacuum pump has been replaced and still very poor braking, I was not impressed, as it was the best part of a days labour, and quite an expensive part that obviously didn’t need changing. Has anyone else had any experience of this and can anyone offer any advice on the next step I should take!?
     
  2. Feb 21, 2019 at 2:04 PM
    #2
    Jim Beam

    Jim Beam Member

    Joined:
    Feb 11, 2019
    Member:
    #2891
    Messages:
    22
    Gender:
    Male
    First Name:
    Donald
    Vehicle:
    1986 CJ7
    Fuel Injection, Dana 44s, T18, 4.10s w/lockers
    Have you checked the other usual suspects like brake fluid level and brake cylinder leakage?
     
  3. Feb 21, 2019 at 2:33 PM
    #3
    aidanmoffatt

    aidanmoffatt [OP] Jeep novice

    Joined:
    Feb 19, 2019
    Member:
    #2905
    Messages:
    12
    Gender:
    Male
    First Name:
    Aidan
    Cornwall, England
    Vehicle:
    2004 Jeep Cherokee (Liberty) 2.5 CRD Limited KJ
    No I haven’t actually, thank you. Well my fluid is filled to max, but I haven’t checked for cylinder leakage. I’ll have a look in the morning.
     
  4. Feb 21, 2019 at 3:26 PM
    #4
    aggrex

    aggrex Well-Known Member

    Joined:
    Sep 12, 2016
    Member:
    #203
    Messages:
    2,112
    DE
    Vehicle:
    Backcountry '16
    Tuffy>AEV>TTO>JW>STech>EVOcage>MagnaFlow>SpiderTrax>RockHard>TF>SpringTail>67design>Bolt>GPCA>Curt>
    "Braking issues" and "poor braking" can mean different things. Inability to stop? Brake pedal goes to floor when brakes applied? Brake pads worn, glazed or contaminated? Rotors rusty, scored or irregular surface? Calipers frozen? Brake lines corroded or leaking? ETC ETC
     
    JKBob 25 likes this.
  5. Feb 21, 2019 at 3:47 PM
    #5
    aidanmoffatt

    aidanmoffatt [OP] Jeep novice

    Joined:
    Feb 19, 2019
    Member:
    #2905
    Messages:
    12
    Gender:
    Male
    First Name:
    Aidan
    Cornwall, England
    Vehicle:
    2004 Jeep Cherokee (Liberty) 2.5 CRD Limited KJ
    Sorry, bad explanation. If I start the truck up with my foot on the brake pedal it goes down after around 15-20 seconds very slowly. When driving it does stop but the pedal is very firm and gets firmer if I have to brake a few times in a row, until the vacuum has built up again. Pads and callipers are all fine, and I’m pretty sure there’s no leaky lines.
     
  6. Feb 21, 2019 at 5:17 PM
    #6
    Jim Beam

    Jim Beam Member

    Joined:
    Feb 11, 2019
    Member:
    #2891
    Messages:
    22
    Gender:
    Male
    First Name:
    Donald
    Vehicle:
    1986 CJ7
    Fuel Injection, Dana 44s, T18, 4.10s w/lockers
    How old is your brake fluid? The master brake cylinder could be failing.
     
    aggrex likes this.
  7. Feb 24, 2019 at 4:51 AM
    #7
    aidanmoffatt

    aidanmoffatt [OP] Jeep novice

    Joined:
    Feb 19, 2019
    Member:
    #2905
    Messages:
    12
    Gender:
    Male
    First Name:
    Aidan
    Cornwall, England
    Vehicle:
    2004 Jeep Cherokee (Liberty) 2.5 CRD Limited KJ
    Brake fluid is pretty new and looks very clean, and at a good level. Thanks for the advice i’ll Check the master cylinder over.
     
  8. Feb 24, 2019 at 11:50 AM
    #8
    Jim Beam

    Jim Beam Member

    Joined:
    Feb 11, 2019
    Member:
    #2891
    Messages:
    22
    Gender:
    Male
    First Name:
    Donald
    Vehicle:
    1986 CJ7
    Fuel Injection, Dana 44s, T18, 4.10s w/lockers
    A good start to figuring out the vacuum issue would be to get a reading from a vacuum gauge.
     
    OFFGRID and JKBob 25 like this.
  9. Feb 25, 2019 at 8:35 AM
    #9
    aidanmoffatt

    aidanmoffatt [OP] Jeep novice

    Joined:
    Feb 19, 2019
    Member:
    #2905
    Messages:
    12
    Gender:
    Male
    First Name:
    Aidan
    Cornwall, England
    Vehicle:
    2004 Jeep Cherokee (Liberty) 2.5 CRD Limited KJ
    I don’t have a vacuum gauge unfortunately, however I have disconnected the hose and put my finger over the end and I can tell you the vacuum is barely noticeable, in usual circumstances it should hold against my finger very firmly. I have ordered a new booster anyway as I’m fairly sure that’s the issue, if not then it’s back to the drawing board.
     
  10. Feb 25, 2019 at 2:51 PM
    #10
    Jim Beam

    Jim Beam Member

    Joined:
    Feb 11, 2019
    Member:
    #2891
    Messages:
    22
    Gender:
    Male
    First Name:
    Donald
    Vehicle:
    1986 CJ7
    Fuel Injection, Dana 44s, T18, 4.10s w/lockers
    A bad brake booster with a leaky diaphragm, can stall out an engine when idling. If you suspect the booster, just disconnect it.
     
  11. Feb 25, 2019 at 11:20 PM
    #11
    aidanmoffatt

    aidanmoffatt [OP] Jeep novice

    Joined:
    Feb 19, 2019
    Member:
    #2905
    Messages:
    12
    Gender:
    Male
    First Name:
    Aidan
    Cornwall, England
    Vehicle:
    2004 Jeep Cherokee (Liberty) 2.5 CRD Limited KJ
    Okay that sounds interesting, can you expand on this at all? So do you mean if I disconnect it when idling it should stall if faulty? Sorry not 100 % sure what you meant. Thank you
     
  12. Feb 26, 2019 at 2:07 PM
    #12
    Jim Beam

    Jim Beam Member

    Joined:
    Feb 11, 2019
    Member:
    #2891
    Messages:
    22
    Gender:
    Male
    First Name:
    Donald
    Vehicle:
    1986 CJ7
    Fuel Injection, Dana 44s, T18, 4.10s w/lockers
    Disconnect the vacuum line into the brake booster and plug the hose end as not to lose any vacuum. If there is a leaky booster, the vacuum should be restored. It will indicate so by using a vacuum gauge before and after. The brake pedal will be pretty stiff without the vacuum assist, but still usable.
     
  13. Mar 11, 2019 at 2:42 PM
    #13
    aidanmoffatt

    aidanmoffatt [OP] Jeep novice

    Joined:
    Feb 19, 2019
    Member:
    #2905
    Messages:
    12
    Gender:
    Male
    First Name:
    Aidan
    Cornwall, England
    Vehicle:
    2004 Jeep Cherokee (Liberty) 2.5 CRD Limited KJ
    Okay so, I have now replaced the booster and the vac pump and still have the same issue!! This is getting very frustrating now! What would any of you do for the next step? I don’t know what else there is to replace? I’ve spent more than I paid for the truck trying to get brakes!! Haha. Someone please help. Pedal still very firm, is it just something I have to live with? Can a thicker engine oil create a better vacuum in the vac pump? If I start it up and it idles for a few minutes the pedal feels nice and easy to press, but just that one time, then it’s firm and slow at stopping. Trying to give as much detail as possible. Is this a common fault?
     

Products Discussed in

To Top