Page 2 of 3 FirstFirst 123 LastLast
Results 11 to 20 of 27

Thread: Brake symptoms

  1. #11
    Join Date
    Dec 2020
    Location
    Otago, NZ.
    Posts
    64
    Total Downloaded
    0

    re brake symptoms

    Vehicle is a '96 d1 300tdi abs.

    Thanks for those suggestions. One mechanic said the same, the other thought it was discs reaching minimum thickness.

    I will replace the vacuum servo unit and go from there:-)

  2. #12
    Join Date
    Jan 1970
    Location
    Central West NSW
    Posts
    13,671
    Total Downloaded
    0
    Quote Originally Posted by dogman View Post
    Vehicle is a '96 d1 300tdi abs.

    Thanks for those suggestions. One mechanic said the same, the other thought it was discs reaching minimum thickness.

    I will replace the vacuum servo unit and go from there:-)
    I doubt very much that its the discs thickness. With my D2 that presents more as a brake shudder when braking heavily, but the power is unaffected.
    Cheers
    Slunnie


    ~ Discovery II Td5 ~ Discovery 3dr V8 ~ Series IIa 6cyl ute ~ Series II V8 ute ~

  3. #13
    Join Date
    May 2012
    Location
    Wannanup WA
    Posts
    1,477
    Total Downloaded
    0
    Quote Originally Posted by dogman View Post
    Vehicle is a '96 d1 300tdi abs.

    Thanks for those suggestions. One mechanic said the same, the other thought it was discs reaching minimum thickness.

    I will replace the vacuum servo unit and go from there:-)
    Up to you, but pretty damn pointless to replace the booster without checking that it is actually getting a vacuum.

    For the "mechanic" with the minimum thickness comment I suggest that you keep away from him, more so when it involves brakes!

  4. #14
    Join Date
    Dec 2020
    Location
    Otago, NZ.
    Posts
    64
    Total Downloaded
    0
    Quote Originally Posted by Old Farang View Post
    Up to you, but pretty damn pointless to replace the booster without checking that it is actually getting a vacuum.
    Dead right. Short of substituting a known good vacuum pump, how can I determine if the existing one is working correctly?

  5. #15
    Join Date
    May 2012
    Location
    Wannanup WA
    Posts
    1,477
    Total Downloaded
    0
    Quote Originally Posted by dogman View Post
    Dead right. Short of substituting a known good vacuum pump, how can I determine if the existing one is working correctly?
    I have not worked specifically on your model, but as I understand it the vacuum pump is mounted on the rear of the alternator. There will be some form of pipe or tube running from the pump to the booster. To be accurate you would need a pressure gauge that also reads vacuum. but a rough idea can be found by disconnecting the pipe, either from the pump, or where it enters the booster. Most systems pull around 15"Hg to 18"Hg, so just putting your finger over the open end of the pipe will give you some idea. The booster end will probably be both easier to get at, plus as it also includes the pipe, both are checked.

    Be aware that the actual vacuum is not what boosts the brakes per se, but movement of the brake pedal allows atmospheric air pressure into the rear of the chamber that then pushes on a large diaphragm towards the vacuumed side, thereby assisting the master cylinder. If that part is not working correctly, or the diaphragm is leaking, then the brakes will be "heavy" to push all the time, and not as you have posted.

  6. #16
    Join Date
    Jan 1970
    Location
    NSW far north coast
    Posts
    17,279
    Total Downloaded
    0
    Quote Originally Posted by Old Farang View Post
    I have not worked specifically on your model, but as I understand it the vacuum pump is mounted on the rear of the alternator. There will be some form of pipe or tube running from the pump to the booster. To be accurate you would need a pressure gauge that also reads vacuum. but a rough idea can be found by disconnecting the pipe, either from the pump, or where it enters the booster. Most systems pull around 15"Hg to 18"Hg, so just putting your finger over the open end of the pipe will give you some idea. The booster end will probably be both easier to get at, [snip]

    Naa, the vac pump is a stand alone unit driven off the camshaft on the RHS side of the block.

    They are made by Wabco and are a pretty ordinary item, the cam follower and lever can break, O ring on the face plate leak, etc
    The afternarket Bearmach ones used to be a more reliable pump.

  7. #17
    Join Date
    Sep 2020
    Location
    Australia
    Posts
    2
    Total Downloaded
    0
    To test the booster pump brakes engine off until all vacuum is expelled, hold foot on brake pedal and start engine, if the booster is working the pedal will sink under your foot a little, this is the vacuum assist working on the booster diaphragm.

  8. #18
    Join Date
    Dec 2020
    Location
    Otago, NZ.
    Posts
    64
    Total Downloaded
    0
    Quote Originally Posted by Old Farang View Post
    <snip> To be accurate you would need a pressure gauge that also reads vacuum. but a rough idea can be found by disconnecting the pipe, either from the pump, or where it enters the booster. Most systems pull around 15"Hg to 18"Hg, so just putting your finger over the open end of the pipe will give you some idea. <snip>
    No pressure gauge. The end of the hose sucks on my finger, weakly - hard to know what 15-18"Hg would feel like.

    Quote Originally Posted by Old Farang
    Be aware that the actual vacuum is not what boosts the brakes per se, but movement of the brake pedal allows atmospheric air pressure into the rear of the chamber that then pushes on a large diaphragm towards the vacuumed side, thereby assisting the master cylinder. If that part is not working correctly, or the diaphragm is leaking, then the brakes will be "heavy" to push all the time, and not as you have posted.
    Yes I wouldn't describe it as heavy at all. The pump is the lead suspect at this point I reckon. According to glencoyne.co.uk they are a 300tdi "known weakness".

  9. #19
    Join Date
    Dec 2020
    Location
    Otago, NZ.
    Posts
    64
    Total Downloaded
    0
    Quote Originally Posted by rick130 View Post
    <snip>They are made by Wabco and are a pretty ordinary item, the cam follower and lever can break, O ring on the face plate leak, etc The afternarket Bearmach ones used to be a more reliable pump.
    I'm looking for the cheapest. So far it's a unipump brand for AUD$285 including postage and NZ tax. Anyone know anything cheaper?

  10. #20
    Join Date
    Aug 2006
    Location
    Melbourn(ish)
    Posts
    26,215
    Total Downloaded
    0
    retrofit a 12V vac pump and close off the port on the mechanical one.

    power via a relay and the ign wire on the injector pump. 20 minute job

    For GM DC 12V Electric Vacuum Pump Power Brake Booster Auxiliary Pump Assembly | eBay
    Dave

    "In a Landrover the other vehicle is your crumple zone."

    For spelling call Rogets, for mechanicing call me.

    Fozzy, 2.25D SIII Ex DCA Ute
    Tdi autoManual d1 (gave it to the Mupion)
    Archaeoptersix 1990 6x6 dual cab(This things staying)


    If you've benefited from one or more of my posts please remember, your taxes paid for my skill sets, I'm just trying to make sure you get your monies worth.
    If you think you're in front on the deal, pay it forwards.

Page 2 of 3 FirstFirst 123 LastLast

Tags for this Thread

Bookmarks

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Search AULRO.com ONLY!
Search All the Web!