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Its Official - Haldex Sucks

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  • Its Official - Haldex Sucks

    I've been having intermittent 4WD engagement issues on this S3 thing. The Haldex system under the rear seat always made a noise from when I bought the car and after a bit of research figured a 'new' primary pump would be best bet to cure that. The ESP light was also always on, but after renewing the clock spring and repairing the lateral G sensor on the steering column I was able to clear those faults. Ran the recalibration sequence then I only get the ESP light after the car starts moving. Fault codes on Haldex for lack of CANbus connectivity with ECU & ABS controller remained and I hoped to find some broken wires between the spare wheel area and the Haldex controller but that wasn't it either.

    20 odd quid on eBay found me another pump but it turned out the noise is from the Haldex controller itself... and a bit of google-ing finds that pretty consistent. Apparently the Gen-1 Haldex controllers are prone to oil creeping past gaskets & seals to start playing havoc with the electronic module.

    So 100 odd quid finds me a spare haldex controller... connect that one to the car and it comes with fault code 65535 'internal error' which is another sure sign of oil ingress - this one had oil spilt all over the connections and the body was filthy - it cracks me up when car breakers neither bother to clean anything or test anything and happily ask for three figure sums - its a total crap shoot. I did get a refund on that one after a prolonged discussion, but anyway.

    So another 120 quid found another Haldex controller plus another pump. Plugged that in today and guess what - same 65535 error code on the controller. Externally this one looked a lot fresher so I felt the need to investigate - at risk of damaging the thing further, but hopeful that a good clean internally would at least give it some electrical sanity. There is a crappy little O-ring which seals the oily side of the stepper motor from the electronic side of things... when that O-ring fails then oil creeps into the clean side and you can imagine all sorts of chaos.

    So anyway, I found an O-ring from a spares box that was a nice looking fit so I took a chance on that and kept going with the clean up job... the next bit is a bit embarrassing and expensive, but its a lesson to us all - when I took off the metal cover for the PCB I was confronted with some god awful snotty gloop that I assumed was potting compound which had been broken down by the Haldex oil... so I set to cleaning that up which was a bad idea as its terrible stuff to scrape off. It was only after a few minutes cleaning that I noticed a bunch of tiny single strand wires from pads on the PCB to the connector pins on the edges. I had broken several off as I had never seen that kind of connectivity before.

    Sorry to be gross, but if you can imagine something the size of pubic hairs from the board to the plug pins then you get the general idea. So deep breath - with some conductive pubes and my magnification spectacles I can fix these. But then it gets worse... while moving over the board with a soldering iron that I was waiting to heat up - a large dollop of solder falls off and splats itself over multiple tracks making some short circuits... ok deeper breath - I can mop that up... turns out I could not - trying three different irons, a hot air system, two different types of mop... the solder just wouldn't get hot enough to melt as all the heat was transferring through the PCB into metal chassis of the controller.

    So the only sensible recourse of action (after 3hrs of dicking around with this thing) was to hit it the PCB with a cold chisel and fatal force from a 2lb lump hammer. That certainly put it well past any chance of corrective surgery but at least I got rid of some anger. What a piece of shy-ite (pardon the language)... So I am 220 quid in the hole and all I have is two spare Haldex pumps (both those tested fine at least), plus the non PCB half of this controller. The S3 was supposed to be some low stress fun and experience for track days - I want to be spannering the S2, not this thing.

    Just realised its Friday 13th so perhaps today wasn't the day to venture inside this fiendish device - I have learnt more about Haldex in the past month than I ever wanted to know. The irony is that the Haldex controller on my car was fitted with the PowerTrak insert for permanent 4WD engagement so mine doesn't even need the stepper motor to work, but because CANbus isn't working then the pump never activates (as the ECU cannot tell Haldex about rpm) and so 4WD doesn't engage - and the ESP light comes on. I am tempted to just bypass the Haldex controller and hot wire the pump on in the meantime, so at least I get 4WD although ESP will always be off. I could probably code the ABS controller & ECU for 2WD to kill the nagging ESP light, but I bet that only creates more hassle than its worth.

    I have to put this down to some expensive hands-on research... and waffling on here about it might give me a better avenue to explore.

    I am sure the more recent Haldex systems are a vast improvement on the 1st generation - but yeah, give me Torsen any day !

    I have photos if anyone cares, but for now its time for a beer.
    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

  • #2
    So what your saying is don't get a early model S3 not even if its very inexpensive and if you do don't ask you to fix it

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    • #3

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      • #4
        Originally posted by LSG
        So what your saying is don't get a early model S3 not even if its very inexpensive and if you do don't ask you to fix it
        Lol - good summary - there are allegedly some reputable sources of refurbished Gen1 Haldex controllers but I rolled the dice on eBay and lost (my temper).
        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

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        • #5
          Car fixing on Friday the 13th should be avoided at all cost! I was very pleased with myself yesterday as my brake pipes looked great. I was wondering where the abs hole was on the off side wing, then realised I had run my pipe through it
          S2 Avant in restoration
          S3 Sportback daily
          Terrecan parts collector

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          • #6
            Originally posted by S2central.net View Post
            I am sure the more recent Haldex systems are a vast improvement on the 1st generation - but yeah, give me Torsen any day !
            Haldex has moved on hugely and is now on generation 5, which works extremely well on smaller cars and is much more fuel-efficient than Torsen as it's usually set up to be "on demand" (exactly how depends on what the car manufacturer specifies).
            Both our cars are 4WD, one with Torsen the other Haldex Gen 5, and both systems work superbly.

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            • #7
              Originally posted by HPsauce
              Haldex has moved on hugely and is now on generation 5, which works extremely well on smaller cars and is much more fuel-efficient than Torsen as it's usually set up to be "on demand" (exactly how depends on what the car manufacturer specifies).
              Both our cars are 4WD, one with Torsen the other Haldex Gen 5, and both systems work superbly.
              Yeah I fully agree - it's designed to be only activated when required. Just a pity it took Haldex 4 or 5 attempts to get a system in mass production that is robust and reliable.

              For mine I want 50-50 torque split all the time and the faults cleared. Then a simple switch can deactivate the controller for FWD when tootling or reversing in tight spots - seeing as Haldex uses a transfer box instead of a centre diff.
              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


              • #8
                It's not designed to run like that and you will burn out the pump if you force it 50 50 all the time.
                http://tuner.ee - http://www.facebook.com/tuner.ee

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                • #9
                  Originally posted by prj
                  It's not designed to run like that and you will burn out the pump if you force it 50 50 all the time.
                  From my understanding of the Audi self study program - The pump runs all the time 24/7 when engine revs above 400rpm - it creates the primary pressure (approx 4bar) needed by the mechanical components of the viscous clutch to build sufficient hydraulic pressure for the plates to engage. The force by which the plates engage is dictated by the position of a stepper motor (in the controller) which moves a pressure control valve. The controversial "powertrak insert" replaces the dynamic control valve with its stepper motor operation and has the haldex clutch fully engaged all the time (as long as pump is running). The insert simply fakes the position of where the dynamic valve would be to deliver maximum clutch engagement.

                  The result is 50/50 torque split and yes rear drivetrain wear would be increased due to full time operation but it's not like the Haldex plates will be slipping, heating and wearing as they are engaged all the time. And it's not like I will doing big miles on this thing.

                  I want the consistency of knowing 4WD is on all the time (at least when the pump is running) - rather than waiting for some lines of code in the ECU, ABS and Haldex controllers to figure out when to activate the 4WD !

                  Turning off the Haldex pump turns the car into a FWD car so it allows you to avoid any potential nasties from effectively having a locked centre diff which can give noises and such in parking situations.

                  There is a lot of nonsense talked about Haldex on many other Audi forums - I spent too long sorting the facts from the noise and feel I understand it well enough now. The SSP explains it pretty well - I can post it here later.

                  There are fabled aftermarket "blue" and "orange" controllers from Haldex which are more geared to performance / track day applications with software changes that allow the Haldex to be engaged more rapidly than the factory items. These "special" controllers are very rare and silly expensive when they come on eBay - there is one there at the moment for GBP700 - which is crazy.
                  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


                  • #10
                    Might not have been the pump, but when we've put dumb controllers in that just set fixed 50/50 something gave out quite quickly.
                    http://tuner.ee - http://www.facebook.com/tuner.ee

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