nickcarguy

'00 A6 Avant, 2.8 Q Tiptronic. Was experiencing a slight delay in downshifts to 1st when coming to a stop. Replaced the ATF and filter which has resulted in a dramatic improvement. Purchased Correct Pentosin ATF, and filter from German Auto Parts.
The fluid and filter was last changed at 90k by an independent transmission shop. When I dropped the pan I was happy to see they used a ZF filter. As for the fluid and pan, it was pretty dirty considering it had only been 27k since last service.
I followed the refilling and topping off exactly . Did notice it only drained approx 5.5 litres of old fluid. While it took a bit over 6 litres when I refilled.
Just wanted to share this with you as it supports many previous posts that clean fluid and correct fluid level can make a big difference in shift quality. Not to mention longevity.

SloopJohnB@mac.com

Good on you. I'm assuming you used vag-com to monitor transmission oil temperature while doing all this?

nickcarguy

Yes. Brought it up to apprx ~105 degrees F. before sealing the fill plug and shutting down the engine.
What concerned me was how black the old ATF was. I'm hoping this isn't a sign of a more significant problem.
The transmission shifts perfectly, and has never thrown a code.
Even after pumping in 6 liters of fresh, clear fluid , as soon as the engine was idling, temperature increased and fill level caused some runoff the fluid that overflowed out was again fairly dirty.
Just illustrates how much "old" fluid remains in the unit after draining the pan.

jseklund

This is why a lot of people will do another fluid change shortly after - to dilute the old fluid even further with new fluid.

nickcarguy

That sounds logical. But the thought of going through the fluid refill process again is such a PITA. I've heard as many as 7 liters remain behind in the torque converter and gearbox. You can never really get it all renewed. Thanks for the input.

SloopJohnB@mac.com

When you drop the belly pan (at least on the 4.2...) there are a couple lines going to an oil cooler that can be disconnected (well, you have to cut those damn one-time clamps and replace with worm clamps) and used to flush the trans. After you change out the the filter and put the pan back on and fill the pan (don't worry about setting the level, leave the filler open) you can then use the trans hydraulic pump to pump out the old fluid through the hose...you have to keep filling the trans with a j-tube (same as the way you filled it in the first place) until clear fluid comes through.

Shut the engine off and hook up the lines to the cooler (which should have drained by now..you can flush it if you wish or if you know the pressure side of the cooler you only have to disconnect one side but most people have to learn which one it is..I can never remember!) and finish setting the transmission fluid level.

Much fluid is going to go out that hose at a pretty good clip so be sure to clamp it onto like a three gallon bucket.

jseklund

Yes, this is the other method - and the A student method in my mind. Some people don't like messing with the torque converter fluid because there is going to be some time where it is running 'dry' while it refills, unless you have a way (machine) to pump it back through there like a power flush. This is just one of those topics with so much controversy for no good reason. I flushed through the torque converter on my mom's car, put in new fluid throughout and it looked absolutely new 50,000 miles later. I just dropped the pan on mine and it looked less new 50,000 miles later, but plenty good for me. I'll have to change it again in another 20,000 at this point...I bet it comes out looking even better.

Dropping the pan a second time is the A- way of doing it. And I'm not sure which way would be less messy - disconnecting the cooler line or dropping the pan again.

GTA_Driver

I swore my torque converter was going, then did a simple fluid change, and it drives like new. Been driving with the shudder for 3 years. It would only occur at certain engine load between 1500 and 1900 RPM, but it's smooth as butter now.

Still original transmission on my 4.2L with 140K miles. I only wish my Allroad had the 5HP24.