Possible hydraulic servo problem?

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  • Key Walshe
    S2Forum Addict
    • Feb 2007
    • 422
    • Home: United Kingdom Current: England

    #1

    Possible hydraulic servo problem?

    Seems there's a new problem with my Power Steering system which is now affecting my brakes! As most will know the PS and Brake warning lights run off the same system, and as I've got a knackered PS pump when the said warning light (!) (looks like that) came on I presumed it was the same seal in the pump gone!

    To my surprise the PS reservoir was dribbling its fluid out of the top which initially indicated too much fluid in there, although I knew there wasn't! After having a look round that, checking the seals on the pump (all ok for now) and then the brake system for any problems we were a little stumped ('we' being myself and StepDad who has his own car repairs business!) as everything seemed ok to look at! The car drove ok for around 10miles, no brake problems or steering issues, then in slow moving traffic the brakes wet very juddery with alot of resistance in the pedal and even less stopping power compared to usual

    Then, that night checking the manual it came to light that the 2 systems (PS & brakes) were more linked than first thought due to the Hydraulic Servo or Central Pressure Reservoir (after searching on here, is it aka the 'Bomb'? Quite apt considering!). Can anyone confirm that these symptoms are the bomb and if so, any reccomendations on how to replace it, ie who to go to as I believe they're around £220from VAG, and I've also read they can possibly be reconditioned, any truth in that and again if so, any reccomendations (I've read 7 Stars in a previous thread)? And the usual question, is it the same as any other Audi models, I'd guess the 20v is the same but any others?

    Sorry for the long winded thread, but my greatest appreciation to anyone who can help out - damn frustrating having this car at times, but so enjoyable when all's well!
    Audi 80 S2 Nothelle N300 Avant, 1993, Amethyst Pearl VW/Audi Car Magazine article about this very car
    Audi A6 Avant 2.5 TDi, 1995, Arctic Silver (now sold)
    BMW E36 325i Coupe, 1993, Diamond Black (now sold)
    VW Polo 1.0L 6N, 1998, Red (the missus' car)
    Aprilia Rs250 motorbike, 1998, Black (the weekend toy)
  • Cullam3n
    S2Forum Maniac
    • Aug 2007
    • 993
    • Home: United States Current: United Kingdom

    #2
    If the brakes are not being assisted, than either the bomb or servo is at fault. To diagnose it as the bomb, after a good run shut off the car and count how many times you can push the brake pedal before it gets hard. If it's a single digit number then your bomb is knackered.

    The bomb is rather expensive from vagparts but you can get them from Paul in Luxembourg for 130euros (before tax + post) for brand new ones. I have one fitted in mine, top chap.

    If your pedal is juddery as in you slam on it and it kind of pulsates as it goes down your servo is knackered (I just retcified this issue on mine)

    HTH

    Comment

    • Key Walshe
      S2Forum Addict
      • Feb 2007
      • 422
      • Home: United Kingdom Current: England

      #3
      Thanks very much for the reply, very helpful! Going off the description of the symptoms then it's both lol and thanks for the namedrop, I'll get in touch with Paul once I've had a chance to look at the problem abit more thoroughly

      Gonna be a lean, lean, lean in the Walshe household this Christmas lol
      Audi 80 S2 Nothelle N300 Avant, 1993, Amethyst Pearl VW/Audi Car Magazine article about this very car
      Audi A6 Avant 2.5 TDi, 1995, Arctic Silver (now sold)
      BMW E36 325i Coupe, 1993, Diamond Black (now sold)
      VW Polo 1.0L 6N, 1998, Red (the missus' car)
      Aprilia Rs250 motorbike, 1998, Black (the weekend toy)

      Comment

      • Cullam3n
        S2Forum Maniac
        • Aug 2007
        • 993
        • Home: United States Current: United Kingdom

        #4
        To be fair, if your servo is knackered, you pedal will be hard no matter what as it's not building up pressure. I put a brand new bomb in mine before I replaced the servo and it didn't really make too much of a difference.

        I think Paul's site is www.custom-auto-craft.com he's an avid audi nutter as well

        Comment

        • S2central.net
          Retired OG Mod
          • Jul 2003
          • 16590
          • Country: Northern Ireland

          #5
          Follow the technical area into Running Gear on http://s2central.net for some hydraulic info.

          This smells to me of bomb or servo failure - theres some valves inside the bomb which can fail. I need to add some other bomb/servo test information - seems like its not all there, but you need a high pressure guage to verify that 140bar is where it should be !
          Paul Nugent
          Webmaster http://S2central.net
          Administrator http://S2forum.com

          1994 S2 Coupe ABY - aka Project Lazarus
          2001 A6 allroad 2.5TDi - family tank
          2003 S4 Avant 4.2 V8 - daily burble

          Purveyor of HomeFries and Exclusive agent for Samco hose kits (S2/RS2)

          There are only 10 kinds of people that understand binary - those that do, and those that don't

          Comment

          • Error404
            Super Moderator
            • Mar 2007
            • 19789
            • Country: United Kingdom

            #6
            My money is on the Servo - I've just had to replace mine, on the CQ which was doing almost exactly the same as yours, but worse - I couldn't stop at all!!
            I'm guessing your servo is on the way out, but not totally fooked yet.

            Doubt its anything to do with the bomb unless its some kind of valve failure like Paul suggested - the brakes work fine on my 20v with a totally dead bomb (pedal hard within 2 pumps).

            Swap the servo first i'd say
            I got one if you need it, came off a CQ with about 110k on it
            Panthero Coupé quattro 20vt
            Indigo ABY coupé
            Imola B6 S4 Avant

            Comment

            • S2central.net
              Retired OG Mod
              • Jul 2003
              • 16590
              • Country: Northern Ireland

              #7
              Ahhh - just found it - there IS a quick servo test on s2central.net in the hydraulic section. That should nail it - though I find access is bl@@dy terrible in that area !
              Paul Nugent
              Webmaster http://S2central.net
              Administrator http://S2forum.com

              1994 S2 Coupe ABY - aka Project Lazarus
              2001 A6 allroad 2.5TDi - family tank
              2003 S4 Avant 4.2 V8 - daily burble

              Purveyor of HomeFries and Exclusive agent for Samco hose kits (S2/RS2)

              There are only 10 kinds of people that understand binary - those that do, and those that don't

              Comment

              • Cullam3n
                S2Forum Maniac
                • Aug 2007
                • 993
                • Home: United States Current: United Kingdom

                #8
                I still have my bad servo that I want to disassemble to see exactly what went wrong, because I did the servo test and it didn't drip anything.

                Comment

                • Error404
                  Super Moderator
                  • Mar 2007
                  • 19789
                  • Country: United Kingdom

                  #9
                  AFAIK you can rebuild some of them, not others. Ask Chris (LHD Kid) he was doing this
                  Panthero Coupé quattro 20vt
                  Indigo ABY coupé
                  Imola B6 S4 Avant

                  Comment

                  • Cullam3n
                    S2Forum Maniac
                    • Aug 2007
                    • 993
                    • Home: United States Current: United Kingdom

                    #10
                    Was reading somewhere that they are not meant to be rebuilt... not sure if the servo on the v6 is different.

                    Comment

                    • Pirvu Eugen
                      S2Forum Extremist
                      • Apr 2007
                      • 1978
                      • Country: Romania

                      #11
                      only the old URQuattro servo unit can be rebuild. http://www.quattro.ca/Urq/Brake_servo_guide.pdf
                      The new models can not be rebuild. I will make some pictures from the both units internals to see the diferences between the old and new models.
                      The idea off Audi is to buy a 600 Euro unit in place of repair the old one with 10 Euro.
                      Good guys, not?
                      Hope this helps!
                      Eugen

                      Comment

                      • LHD_Kid
                        S2Forum Possessed
                        • May 2006
                        • 3696
                        • Home: England Current: Belgium

                        #12
                        Originally posted by Pirvu Eugen
                        only the old URQuattro servo unit can be rebuild. http://www.quattro.ca/Urq/Brake_servo_guide.pdf
                        The new models can not be rebuild. I will make some pictures from the both units internals to see the diferences between the old and new models.
                        The idea off Audi is to buy a 600 Euro unit in place of repair the old one with 10 Euro.
                        Good guys, not?
                        Hope this helps!
                        Eugen
                        Yes, this is correct..... Eugen kindly dismantled a few different models of servo from his 'stock' to see if there was any way of replacing any internal seals, and only the very early ones are servicable, unfortunately...
                        This means, as said, you spend 360 quid instead of a fiver....
                        Chris
                        Honda CBR 1100XX Blackbird Turbo....undergoing major changes.....
                        S2 Coupe... bit easier off the line...
                        '03 ZX12-R daily hack.... lots of nice bolt ons...

                        Comment

                        • Key Walshe
                          S2Forum Addict
                          • Feb 2007
                          • 422
                          • Home: United Kingdom Current: England

                          #13
                          Thanks for all the replys and advice, s2central especially thanks for the link to your site - some great info on there, not just on this subject but loads others too! But, when you say there's a test in the Hydraulics section I couldn't seem to find that section, unless it was THIS section of the brakes bit, brakes_06!

                          And LHD_Kid, when you say it was only the very early ones that are servicable, I guess you mean even earlier than a '93 S2 Avant?
                          Audi 80 S2 Nothelle N300 Avant, 1993, Amethyst Pearl VW/Audi Car Magazine article about this very car
                          Audi A6 Avant 2.5 TDi, 1995, Arctic Silver (now sold)
                          BMW E36 325i Coupe, 1993, Diamond Black (now sold)
                          VW Polo 1.0L 6N, 1998, Red (the missus' car)
                          Aprilia Rs250 motorbike, 1998, Black (the weekend toy)

                          Comment

                          • LHD_Kid
                            S2Forum Possessed
                            • May 2006
                            • 3696
                            • Home: England Current: Belgium

                            #14
                            Originally posted by Key Walshe
                            And LHD_Kid, when you say it was only the very early ones that are servicable, I guess you mean even earlier than a '93 S2 Avant?
                            Fraid so mate.... turns out, it is even earlier than a 1991 3B too...
                            Sorry
                            Chris
                            Honda CBR 1100XX Blackbird Turbo....undergoing major changes.....
                            S2 Coupe... bit easier off the line...
                            '03 ZX12-R daily hack.... lots of nice bolt ons...

                            Comment

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