Can anybody recomend a good high interest building society account as I want to start saving for a new autobox for my 270CDI which I would imagine will be around 3K!
My reason being that, Mercedes inform me that the fluid doesn't need changing, never ever, and, will not entertain doing a change for me. I know therefore, that the box will cease to exist at around 100,000 miles.
Would anybody know if it's possible to change the fluid without major work or should I just start saving!
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Why do makers persist with this "fill for life" nonsense? I knew manufac. had tried this with coolant and had the obvious failures, but i had no idea mercedes were doing it with Auto fluid.
I have no idea about changing ATF on this car, but hopefully Aprilia will be along shortly to help you out. I think he is very knowledgable on mercedes autos (and most other things car related).
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Yes, Aprilia will have an authoritative opinion. I would also call in to a local MB independent specialist and see what they say, which could be anything from "I'm afraid MB are right" to "Sheer nonsense, designed to boost their appeal to fleet managers; the fluid should be changed regularly and this is how it's done . . ."
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As if by magic.....
Ah, well. Since 1998 Merc have pretty much settled on the 722.6 electronically-controlled five-speed 'box for all of their cars. This 'box uses a synthetic ATF and is said to be 'filled for life'.
Most MB dealers are very very wary of 722.6 - there have been quite a few problems with it. That's why they don't want to change the fluid for you. It is EXTREMELY senstive to fluid level (i.e. basically a design fault).
You can easily drain the fluid, and preferably the change the filter at the same time. 50k miles is a good time to do this. A normal drain/refill will swap about 6 litres; the transmission holds about 11 litres (rest is in the TC).
When refilling you need to have the fluid temp at exactly 80deg.C. when you top up - this is to get the level correct. MB dealers use a diagnostic tool to read the ATX temp sensor directly. You may need to buy a 'service' dipstick if your transmission doesn't have a dipstick as standard (most don't - to discourage non-dealers from doing anything with the transmission).
BTW, a MB recon transmission will run more like £4-5k rather than £3k !!
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Thanks for (another) very interesting post Aprilia.What happens to the box if the level is incorrect? What sort of mileages are these things reaching on the original fluid before they go bang?
I was always taught that ATF should be changed every 12 months and that this was pretty much essential.
Perhaps worth leaving well alone Al 42.
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Thanks for (another) very interesting post Aprilia.What happens to the box if the level is incorrect? What sort of mileages are these things reaching on the original fluid before they go bang? I was always taught that ATF should be changed every 12 months and that this was pretty much essential. Perhaps worth leaving well alone Al 42.
Overfilling is as bad as underfilling since it over-pressurises the tranmsission.
Common failures on these transmissions have been torque covertor clutch failure; front drum bush failure (its only a plain bearing) and planetary gearset failure (K2 clutch drum).
Some have only made it to 50k miles - but that was mainly the earlier ones. You should get to 100k without a problem, even if the fluid is not changed. There is also the possibility of electronic failure - the shift-switch can go fautly and there are six solenoids on the valve body. Best not to think too hard about it.......
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Thanks very much for the advice - looks like the fluid's staying put then! 4-5K!! I'll just have to keep my fingers crossed that nothing goes wrong.
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For the savings account you could use www.moneysupermarket.com
Unfortunately I have no knowledge on autoboxes nut I'm sure some else will come along with more knowledge...
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306 2.0 SE Cabriolet
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>>There is also the possibility of electronic failure - the shift-switch can go fautly and there are six solenoids on the valve body. Best not to think too hard about it.......
Definately! I never knew mercedes had had this sort of trouble and i always thought they produced the best auto boxs available.
Sounds like a pure design fault to have a system that is so sensitive to fluid level - Not to mention the other weaknesses.
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To be fair, all transmissions tend to have their weak points. This 722.6 MB box is probably no better or worse than other 'electronic' boxes in that respect. It is very touchy on fluid level though.
The 722.6 is totally different to the pre-'97/98 MB autoboxes which were 4-speed hydraulic affairs. Much simpler and more reliable, plus cheaper to fix.
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Aprilia
My 1996 E320 Coupé has a five-speed box. Ah, I think I've already answered the question I was about to pose: from the number 722503 04 (etc.), I see that it's not a 722.6 box.
And I am reminded that the last time an MB dealer servicing department touched that car they refilled the autobox with too little fluid -- at least a litre short -- at a major (36k) service, and it started playing up immediately. Still, with that much shortfall you can't blame it, can you?
As a general comment based on ownership of three MBs (two currently) and driving several others, I wouldn't say that the autoboxes are the smoothest ever made. In that connection, I've heard from a fellow owner that replacing what MB call the vacuum box can improve smoothness significantly; as it costs under £30, I think I may do that, at least on the older car.
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Yes, the older boxes are pretty crude (but effective and robust). They are vacuum controlled and all the piping etc has to be in tip-top condition. I think you are talking about the vacuum modulator. Yes, you could try replacing it - if it has gone weak or leaky then you will get hard shifting. Might well be worth replacing.
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