Gearbox Issue & Limp Mode

[discostu]

My RS6 has suddenly started switching to limp mode.
When I start it and drive the change between 1st and second and low revs feels like it slipping/hesitant, is this just how limp mode works or do I have a gear box issue that is causing limp mode?

Any help would be much appreciated. desperately hoping it's not time for a new box

[SteveCuz]

Check the ATF you might be low.

Stephen

[Shoppinit]

Difficult to tell without doing some proper diagnostics.

Most likely causes are low ATF or worn TC.

[discostu]

Disaster averted, new ATF fluid and strainer (4 litres out and nearly 6 litres in), box now running super smooth.
Elsawin disc proved invaluable, £10 well spent.

[mavada]

Did you do it yourself?

[discostu]

Yes, it's fairly straight forward but I wouldn't have done it without service manual. The fill point is important at the right temperature, so there is some arsing about on the final fill.
Pleased I did it as Audi wanted £330 to do the change and another £130 to run a diagnostic. It's cost £125 on ATF and the strainer and a morning to do it. You'll need a pit or a lift as the car needs to be level so you can't do it on a jack.

[mavada]

ok but you didnt flush it ?

[AdrianE]

I gather it's impossible to change all the fluid at once as a lot doesn't drain out of the torque converter? Needs about 3 changes to get it all out! What's recommended approach for flushing?

[mavada]

so it is 3x125... maybe audi will do the flush within the 330 and do the diagnostic yourself...

[Golfather]

Disaster averted, new ATF fluid and strainer (4 litres out and nearly 6 litres in), box now running super smooth.
Elsawin disc proved invaluable, £10 well spent.

Good man, well done on the DIY front
Owning VAG without ElsaWin should be made a crime

[Shoppinit]

I gather it's impossible to change all the fluid at once as a lot doesn't drain out of the torque converter? Needs about 3 changes to get it all out! What's recommended approach for flushing?

Yup, but you can get 70% odd percent of it. Better than nothing. You can always do another ATF change in a few thousand miles then you'll get 91% of it.

Some places use a transfuser on the ATF cooler to draw out the old and replace with new. Of course, doing it this way means that you don't desump to get at the filter.

Was your level low? Did you find the source of the leak?

[mavada]

Why is it that important to refill it at a specific temperature as shown in ElsaWin?
How long will it take to cool down a full heated gearbox to reach that specific temperature?

[Shoppinit]

Because when the ATF get hot it expands. A lot. The level is correct for a specific temperature (and hence density) only. If you do it when the engine is hot, you won't put enough ATF in. And you can't do it with the engine off because you need the pump to be circulating the ATF while you fill it or you won't be able to put enough in.

Best way is to have the box stone cold (leave it overnight) and whack as much ATF as you can in while the box is still cold. This is why you fill it as much as you can before starting the engine. Then start the engine and have someone go through the gears in tiptro while you stuff as much ATF in as possible.

I think the temperature given for checking the level is 35°C (to be confirmed) so if you have put enough ATF in then it should start to spill out of the fill plug when you start to get near 35°. When the Vagcom reads 35, put the plug in and your level is good.

[mavada]

ok clear is always, thanks Shoppinit

[chunky79]

Disaster averted, new ATF fluid and strainer (4 litres out and nearly 6 litres in), box now running super smooth.
Elsawin disc proved invaluable, £10 well spent.

Good man, well done on the DIY front
Owning VAG without ElsaWin should be made a crime

Is there just 1 type of elsawin workshop manual?

dunc