Transmission Fluid, Torque Converter or not?

[jakewinning]

Hi All,

Just picked up a C250 AMG Sport Automatic 62 plate, 47k miles. As I've just picked it up and it's due a service I've dropped it into a Mercedes Indy for a few bits of work, here's what I've gone for:

- Service B (which they tell me includes Air Filter, Pollen Filter, Fuel Filter, Oil Filter and Oil change plus the other necessaries)
- Rear Axle Oil Change
- Brake Fluid Change
- ATF Fluid Change

Now my main question lies with the ATF Fluid Change. I've read some really conflicting thoughts on this. Most people seem to say that you shouldn't touch the Torque Converter and shouldn't drain it (which is also what this garage believe on a car of this age). Others have said that if you don't drain it, your just lazy..

My question is, am I doing the right thing by having these guys change the ATF Fluid without Torque Converter? Anything else I should be worried about? The car also seems to jitter ever so slightly when cold on gear up, from what I understand this is standard with the 7G?


Thanks in advance and sorry for the long post!


Cheers,
Jake.

 

[Lyserman]

The transmission and the torque converter are both fed by the same oil supply.
The oil left inside the TC will be just as old as the oil drained from the sump.

How would you feel if the garage told you they were only going to drain half of your engine oil and then top it back up when doing an engine oil change?

Tony

 

[jakewinning]

Thanks Tony, I agree, that's why I'm confused to be honest with you.

The garage I took it to said we don't touch the Torque Converter on a car that's only done 47k miles because it can cause issues. Can you think of what issues he could be talking about?

I've already dropped the car in with them so hoping it's not too late to get them to do this properly!

 

[gianton]

Your car has the 7g+ tranny, which needs an oil/filter change every 75k miles or 4 years. I do mine every 55k miles just for peace of mind. Last change was at a local MB dealer and I insisted to have the TC oil drained as well. Total oil used was just under 10 litres and the type was the A 001 989 77 03.

Show them the video below how to find the TC drain plug (1:50 min)

https://www.youtube.com/watch?annot...&feature=iv&src_vid=_-72EN_pqUU&v=sP0FfkfQCLg

 

[Lyserman]

Maybe they misunderstood.
I cannot think of any issues that could be caused by changing the ATF.
To me, it sounds like them not wanting to take the extra time to flush out the old oil.

Not all cars are fitted with a TC drain.

Tony

 

[Abcan]

I have the same box in my 62 plate e Class. It's done 50k and it's never jittery as you describe. Mines due it's first fluid change at its next service that's due in November.

 

[kid-jensen]

At 47 k miles, there will be no isues with contaminants which might get dislodged by fresh oil, so the TC fill is definately reccomended.

As you mentioned, there's conflicting information as to whether the TC has a drain plug in this box, but if it doesn't, it can still be flushed, it just takes more time and equipment.

Although expensive, a transmission oil change is a worthwhile investment..

 

[jakewinning]

Thanks for all your responses, much appreciated!

So the guys did an ATF oil change (apparently the old stuff was very dirty) and reset the Gearbox module and said it will be snatchy to start with and will ease out as it learns from my driving style.. I'm hoping this is the case as it seems pretty snatchy between 2nd and 3rd at the moment.

I've read that if that doesn't resolve it then a software update to the TCU is recommended. I've heard lots of good things about a company called Eurocharged. Anyone have thoughts on this?

 

[gianton]

Thanks for all your responses, much appreciated!

So the guys did an ATF oil change (apparently the old stuff was very dirty) and reset the Gearbox module and said it will be snatchy to start with and will ease out as it learns from my driving style.. I'm hoping this is the case as it seems pretty snatchy between 2nd and 3rd at the moment.

I've read that if that doesn't resolve it then a software update to the TCU is recommended. I've heard lots of good things about a company called Eurocharged. Anyone have thoughts on this?

Did they flash the TC fluid too?

 

[jakewinning]

Did they flash the TC fluid too?

Nope they wouldn't do it. Said it would cause problems, I explained all the points you guys sent across but they said they've experienced it causing lots of problems and won't do it..

At that stage they already had the car and had done most of the work and it was quite a trek to get it there and back so I went ahead as it was.

I know, I should've been more persistent..

 

[John]

Hmm, didn't do the TC and now the gear changes are snatchy.

I'm surprised the ATF is that dirty in a car of that age and mileage.

I wonder how feasible a 75k mile change is when the oil is that bad at 47k.

 

[jakewinning]

Yea I'm dubious too. I called the guy today and he said that they had reset the gearbox adaptations which means the gear change will be snatched for the first hundred miles or so while it learns your driving style.

Hasn't learnt yet and it's been that. He's been good though in that he said I can just head back and they'll take a look. I'm hoping it's something really simple as I've still got 3 months warranty from the dealer I bought it from and if it's not just a standard service thing I'll have to get them to sort it/take it back.

Has anyone experienced this same behavior with their 7g tronic plus? Snatchy 2->3 and 3->4 then silky smooth from there. Any ideas what it could be?

 

[gianton]

I had the TC fluid flashed on both times, gear changes are silky smooth always. My car has 150k miles and had the fluid/filter change both on gearbox and TC twice so far.

 

[exvolvoman]

Completely different car I know, 2004 C180K, I'm about to do an ATF change and ordered a kit from MB of Newcastle, 4lts oil, filter and gasket. That isn't enough for a complete oil change, so I'm assuming the torque converter is not drained.
Would like your guys comments please?
Also, is in necessary to replace the oil pan bolts?

 

[brucemillar]

Most garages (dealer on independent) will NOT change the TC fluid unless specifically requested to do so. Over time (and changes) this will balance out as the TC fluid mixes with the new fluid in a cyclical process.

* Some will simply drain and refill the trans then repeat within a few hundred miles.

* Others will remove the hoses and drain the lot (if asked to do so)

* Some (like Wright Tech) use a machine that does the lot including measuring and weighing.

Re-setting the adaptions can give you a noticeable change in shifts as it re-learns your style. This is entirely dependent on what the box had learned previously, so cannot be generalised to all cars.

 

[John]

Yea I'm dubious too. I called the guy today and he said that they had reset the gearbox adaptations which means the gear change will be snatched for the first hundred miles or so while it learns your driving style.

Hasn't learnt yet and it's been that. He's been good though in that he said I can just head back and they'll take a look. I'm hoping it's something really simple as I've still got 3 months warranty from the dealer I bought it from and if it's not just a standard service thing I'll have to get them to sort it/take it back.

Has anyone experienced this same behavior with their 7g tronic plus? Snatchy 2->3 and 3->4 then silky smooth from there. Any ideas what it could be?

The only time I've ever experienced a snatchy auto was when I had a Saab 9-5 Aero HOT on an 04 plate.

Changing the fluid resolved but it did come back again albeit probably needed another fluid doing by then.

I'm not sure I agree with adaptations causing it - it should still be smooth regardless.

I wonder if the firmware is up to date on your gearbox although arguably, if it didn't do it before the fluid change, it could still be a mechanical issue maybe related to how it / what was done, rather than an electronic one.

I had my fluid on my previous 722.6 twice by Wright Tech mentioned above, albeit a different gearbox but still adaptive, and never experienced any snatchyness. And as Bruce states - WT flush the whole lot!