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Un-Sticking Your TDi VNT Turbo Vanes.....

Discussion in 'A4/S4 forum(B5 Chassis)' started by evilscotsman, Nov 5, 2010.

  1. scr8pdo
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    scr8pdo Member

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    How hard is it to remove the actuator arm so that I can test the actuator arm, if its a total nightmare I will use long nose pliers, thanks in advance, Ste :)
    #81
  2. Tolak
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    Tolak Member

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    Based on similar Garrett t/c on different car:
    The actuator bellows has the vacuum tube entering one side, and the pull-rod coming out of the other side. This pull rod then drops down to the actuator arm on the bearing side of the turbo. So if you grab the actuator bellow like a ball, you should find the actuator shaft between your fingers, and you can then squeeze to pull the actuator up.
    Should move with less force than a tennis ball takes to squash, and then drop back to fully relaxed. If you hear air hissing, you might have a vacuum leak (tube) or a problem with the actuator (most unlikely).
    The vacuum is modulated by a trembler valve (identified as N75, above), so you get the amount of vacuum to achieve the scheduled turbo boost; if the control reaches full range without getting the boost, then the fault will be reported.
    Note that only the VNT/VVT is in the hot area; the actuator is almost 4" away, so much cooler, and the electronics of the trembler valve are well away from the hot area.
    HTH,
    Tom
    #82
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  3. evilscotsman
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    evilscotsman Space Cowboy

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    very well put Tom.

    Folks, what sticks, is the ring the actuator operates on, and it usually sticks in the full boost position with the vanes closed (well pointing to the hotwheel / exducer) - hence when you use MM to soften and absorb the carbon, you should be able to get the actuator arm moving (which is actually moving the vnt ring and vanes inside the hot end. (MM = Mr Muscle)

    And its only needed if you get over-boost limp mode, on a VNT turbo diesel.

    also, never ever put MM in the intake side of the turbo!!! it reacts violently with aluminium and produces a toxic gas, never get it in contact with alloy. At least MM has a lower concentration than you may have made yourself, I never went into that before but you can make a strong version for pennies if you find MM cant shift the carbon cos its so thick....MM is Sodium Hydroxide, otherwise known as Lye, or Caustic Soda (as used in Biodiesel production - key element for de-soaping the veg oils) - you can buy caustic soda crystals in a number of places, and read the instructions. Always add the crystals to water, never the other way round, and wear goggles, gloves (and an apron if your a clutz) and inject the solution using a plastic paint mixing syringe and follow the original instructions after that.

    Sodium Hydroxide burns hot too so when it gets blown thru the cat, whats left of it ignites and helps clean off the mesh as well. My cat was cleaner than before after doing it. Its the only substance known to man which can dissolve carbon into itself apart from a chemical mixture called Piranha Fluid which is Hydrofluoric acid, and Sulphuric acid, a VERY VERY nasty combination, that even eats glass. Its used to clean carbonized glassware in a chemistry lab.
    #83
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  4. jbh
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    jbh TDi lover

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    so Scott when are you doing the next chemistry lesson? what is it you do?
    #84
  5. Tolak
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    Tolak Member

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    Slightly worried about suggesting the use of this, especially if someone is a klutz!
    Also, it is typically better to try two iterations of a slightly milder (and safer) solution, because the effect is cumulative.
    But I agree with all the rest of your comments, and thanks for your kind comment.
    #85
  6. evilscotsman
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    evilscotsman Space Cowboy

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    lol cheers man, I'm an electronics engineer, in process control & automated machinery so I have worked in a few chemical plants or similar like paper mills, power stations etc and so you have to find stuff to work in some difficult areas, they use a list of preferred chemicals for certain tasks, like decarbonizing a large steam plant boiler tubes in a firebox. Thats how I found out about Sodium Hydroxide shifting carbon.

    The MM foam is easy to use if you get the bit right with the tubing (get it to the bowels of the turbo cast iron end) and get the foam to fill the hot wheel casting (brown cast iron end again for those that arent sure.)

    So to summarize, fill your brown end right up with foam so it touches every part of your ring and soaks your nozzles.

    (ooooh suits you Sir!)

    1267092318-paul_whitehouse_suitsyou.jpg

    I've got it on my skin before and it doesnt burn readily cos its like 6% NaOH if you rinse it off fairly soon, but it works well after a couple of hours on the turbo. Too long, and its solvent evaporates and it starts to gel, if you do that by mistake then just add another filling of foam, wait an hour and then button up and blast it out on a run. The new stuff will turn the gelled stuff into liquid again pretty quickly.

    Raw caustic soda in pure concentrated liquid form is EVIL kids, its really bad stuff that instantly dissolves eyeballs and noses, it's as dangerous as sulphuric acid , its just at the opposite end of the PH scale. It turns body fat instantly to soap (true, thats how soap is made - chemistry lesson 2 LOL)

    Use the MM foam ok. Don't make your own.

    walterwhitequotebreakin.jpg

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    Last edited: Sep 14, 2013
    #86
  7. Tolak
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    Tolak Member

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    So that's why we speak the same language; I'm a system engineer, coming from a software background, working in avionics, so describing a process, and understanding the reasons behind it, are my bread and butter.
    Strangely, this forum doesn't seem to be too wrapped up in the electronics controllers, and is biased towards mods and basic mechanical stuff, which is good. Just moved over from another forum (changed car) and there it was all codes and diagnostics.
    Anon
    #87
  8. evilscotsman
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    evilscotsman Space Cowboy

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    lol I get ya. I just like tinkering with 90's TDI's but sometimes things need more explanation. I try not to be too stuffy and have a laugh tho.
    #88
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  9. Mu81n
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    Mu81n New Member

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    Evening,

    Just out of curiosity, would it be a better idea to get a blanking plate with a hole big enough to insert the 3mm silicone tube, cover the turbo from the exhaust side and fill it with Mr Muscle? This method apparently is also used, when using innotec.
    #89
  10. PAULF
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    PAULF Member

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    That's essentially what I did with my 2.5TDis.

    Three nuts to unbolt the exhaust, tuck the tube behind the turbine, squirt and cover with cardboard - before the foam jumps out.

    A lot easier than trying to feed through and the result was still a freed-up actuator.

    Regarding Tolaks comment,
    As I see it, codes and diagnostic computers should be regarded as one more tool to assist in the driving experience - along with tape,penetrating oil and big hammers!
    #90
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  11. Tolak
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    Tolak Member

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    Agree about using any hole to get the foam into the turbine. However, the inlet manifold upstream of the EGR and especially the head (upstream of the exhaust manifold) is aluminium, and so will be damaged if you put too much foam in, so the foam content needs to be measured/controlled in some way. Using top-down is easier, since the exhaust is steel, and only spillage upstream of the turbo is an issue.

    Driving experience, absolutely. But some of the issues are diagnosed with codes, and some with good old-fashioned mechanical skills, so those problems need everything we can use. Working out what the problems are, so all that remains is the "simple" repair, is the preferred route; these garages who swap one component after another (charging you at every step) are just making a mockery of diagnostic skills, and the customer's wallet. I would be much happier if they bore the costs of items found en route, so they could claim the benefit of their skills.
    #91
  12. ColinT
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    ColinT New Member

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    I have recently had this problem with my 1998 Audi A4 1.9TDi the Mr Muscle worked a treat on it.

    Many thanks for the info.

    Colin
    #92
  13. slizza786
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    slizza786 Member

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    Sorry to revive an old thread but did your car have an egr cooler? What engine type was it? Bkd? My aluminium pipe goes from the egr valve to the egr cooler and then there's another pipe that goes from the cooler to the turbo which is extremely hard to get access to from the top and i tried already from underneath the car but the frustration got to me so I want to try another attempt from the top regardless of how long it takes
    #93
  14. DeNi
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    DeNi New Member

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    mine is 53plate, so has same cooler as yours, to get easy access like on those pictures i had to completely remove it (left it hanging on rubber pipes only).
    #94
  15. DeNi
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    DeNi New Member

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    Just abit of info. Did this on my car 13months ago (~5k miles). Mostly driving on cold engine round town so turbo gets covered in that soot really quick. had to do it once again now because limp mode appeared again couple weeks ago. Well, this time it was much quicker because i knew what i am doing this time. Thanks once again to this topic owner. saved another ~£200 for turbo cleaning? :)
    #95
  16. dazzag
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    dazzag New Member

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    i've been trying to solve the dreaded limp mode problem with my 97 1.9tdi i had high hopes after reading this thread. I thought everything went well. The pipe went downwards as much as i expected it to. But no change i was expecting a plume of smoke after starting up but there was nothing??

    Maybe the pipe did not go where i expected it to?
    #96
  17. gb484
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    gb484 New Member

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    A million thanks for these posts!! This should be required reading for anyone with a TDI! Could not get the actuator arm on my Merc Sprinter 212d to move despite best efforts. Found post re using Mr Muscle and gave it a try. Still no movement. Needed to go out to shops after spending much time trawling internet and trying various things, so off we set with the van running like a pudding and making an horrendous clacking noise from the engine. As we get into town, about 5 miles away, the clacking noise starts to change in tone but the EDC light that had been on permanently for almost a week stayed on and still no real improvement. Shopping done, we climb back in and I fires up the engine. Couldn't believe my ears or eyes. EDC light out and turbo boost back to normal. Boy, did I enjoy the drive home!
    #97

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