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Transmission fluid, coolant contamination?

Discussion in 'Engine, Drivetrain, Fuel and Exhaust' started by Conor, Oct 11, 2019.

  1. Conor

    Conor Senior Member

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    Hey guys,

    I've just come across an article online outlining an issue with the W211 E55K. What happens is the transmission cooler fails, and coolant gets into the transmission fluid, thus absolutely killing your transmission and resulting in a very expensive repair.

    The issue is commonly referred to as Strawberry Milkshake of Death (SMOD).

    I do understand that some makes/models are more susceptible than others, but I am wondering is this something I need to be keeping an eye on in my R230 / S212 s.

    Just curious what other peoples thoughts are on these. A main reason for asking is that, considering my S212 is 192k miles old, i've often said the only two things I am concerned about are transmission and catalytic converter (I'm not too worried about the big block engine). As if these go, they will be expensive to fix.
     
  2. V6Matty

    V6Matty Senior Member

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    Only really affected the early 211’s fitted with Valeo radiators ( some 163’s as well I think) it wasn’t the rad that failed but a coupling at the rad. If it hasn’t had an issue by now then its very unlikely to be an issue. The correct name for this is Glycol Contamination, symptoms are very jerky gear changes, whine from the box at certain revs, slipping/hunting between gears and another thing that I can’t remember right now.
     
  3. Bogus

    Bogus Active Senior Members

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    This can happen in any vehicle where the ATF cooler is incorporated in the radiator. The key is clean well maintained cooling medium with the right mix of coolant / antifreeze which of course also contain corrosion inhibitors. In my old Toyota Hilux, with an unknown history I choose to fit a separate ATF cooler, blanking off the in rad one. if you are confident that the coolant has always been maintained in good nick, probably no need to worry.
     
  4. alexanderfoti

    alexanderfoti MBO Forum Supporter Authorised Forum Supporter

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    Yes any vehicle can be affected. Most MBs have combined ATF and engine coolant radiators but there was a spate of failing valeo radiators that affected 211/219s a lot.
     
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  5. OP
    Conor

    Conor Senior Member

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    Ok, I guess the wisdom of a friend rings true again.. oil, in this case fluid, is cheap and metal is expensive.
     
  6. matthew k

    matthew k Senior Member

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    Vibration under load in higher gears is the other symptom I seem to remember. Early Valeo Rads, something to do with the internal crimping being done incorrectly or something. I had a 2003 E55 fitted with one, I was very worried, but did 6k trouble free in it. The consensus seems to be if it's still ok now it's 'likely' to be ok. Still, given the damage it can do to the box, the main one I know of is stripping the clutch plate material away, probably best to change at some point.
     
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  7. V6Matty

    V6Matty Senior Member

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    That’s was the other one I couldn’t think of, thanks Matt

    Your right essentially strips all contact material, washes out all the bearings and all the material clogs up the fluid channels, meaning it’s pretty much a new gearbox that’s needed or a painstaking rebuild.
     
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  8. V6Matty

    V6Matty Senior Member

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    Changing the fluid makes no difference, it was a factory/manufacturing fault (although I don’t think Mercedes ever admitted as much)
     
  9. davemercedes

    davemercedes Senior Member

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    That's okay but at least it might have been seen before a calamity if the auto box was serviced. I think MB did automatic owners a real dis-service with the vague "sealed for life" period. Every now and then when new members pop up, amazingly the same old question of whether their auto box has ever been serviced arises. I always point out that this is a job for an Indy (i.e.:not your "local garage") and it should be done NOW if it's been omitted.
    - The price of a service versus an auto box!
     
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  10. LostKiwi

    LostKiwi Senior Member

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    I had a Toyota Land cruiser that had suffered the same issue. When the gearbox was pulled apart the rebuilders were amazed at the amount of rust in the box (and this was after it had been 'fixed' by the previous owner and had a replacement radiator and external cooler fitted).
    Apparently it was a nightmare to put right.
     
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  11. davemercedes

    davemercedes Senior Member

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    I had a Daewoo (Ssangyong) Musso 4x4 that I ran for about 4 years (on vegetable oil!)...
    It had VERY comfortable leather seats jokingly referred to as an armchair on wheels and the auto box was a Borg-Warner Australia hybrid which generally felt good. But it developed a frightening jump down through the box. I found through the owners club that the correct transmission fluid is "Castrol TQ95" which is a scarlet red colour. Changing the fluid was an absolute pig especially as it was "fill to overflow".
     
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  12. umblecumbuz

    umblecumbuz Senior Member

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    It's a common enough design, but I've never liked a 'radiator within a radiator'.
    No doubt an efficient manufacturing solution, but by choice give me separate heat exchangers every time.
    At least you get immediate visible warning if something begins to leak, and no cross-contamination.
     
  13. davemercedes

    davemercedes Senior Member

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    When I ran a Triumph parts distributorship (in a former life!) I used a trick of supercession records to link the towbars on the automatic 2000 and 2.5PI cars to the associated oil cooler kit (yes a separate oil cooler!) with a note to staff to "sell with tow bar".

    The details about the oil cooler kit and its technical benefits were hidden away in a Technical Newsletter and adding one into the total upgrade price frankly wasn't too bad - as usual when compared to the price of an auto box/overhaul. I always thought it surprising when Joe Bloggs came in to get a tow bar - usually before driving down to the South of France/Italy/Spain on holiday and when the technical note popped up we would explain how it kept the auto box safe etc. Incredibly about half of them refused it even when shown the official technical bulletin!
     
  14. LostKiwi

    LostKiwi Senior Member

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    The design provides a couple of benefits:
    1. Faster warm up of the oil.
    2. Regulated temperature of the oil.

    The first of these helps reduce wear.
    The second allows more accurate tuning of the drivetrain to get smoother changes.
     
  15. umblecumbuz

    umblecumbuz Senior Member

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    Fair comment. Shows that there are pros and cons either way.
    Atf overheating can be a bigger wear factor than warm-up time - especially when towing hard - but obviously this can be designed out.
    You pays your money ...
     
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  16. EmilysDad

    EmilysDad Senior Member

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    Quite common now that the dip stick has been removed ;)
     
  17. davemercedes

    davemercedes Senior Member

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    Well, that was probably the last couple of times I lay very uncomfortably on f-f-cold concrete to do anything (essential or not)! And I'm pleased to say "never again!"
     

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