MP4.2+6.0

So, I'm doing the W12 tranny service at just past 100K miles. I did the first drain a few weeks back. I only got about 4.5L out, so only about 45%. It left me concluding I probably needed 3 changes to get most of the fluid cycled out. On this second drain, the used fluid still came out quite gray, and nothing like the 4.5L of new "blue" W12 type fluid I pumped in a few weeks earlier.

I previously bought the filter and gasket, so figured it was time to bite the bullet and do the pan and filter pull for the second change. Not easy, as I knew to expect with the big W12 exhaust stuff all around the tranny area. I also wanted to get the gear oil changed (related post to follow) as well as the coolant, so figured I would tackle it all at once. I have done the coolant before so know that drill. Plus, I wanted to carefully inspect the heater control valve that is under the plenum cover to the left of the HVAC filter, so I needed the coolant out for that anyway. BTW, having opened it up (carefully) a section at a time, I found virtully no deposits or residue inside of it. I have changed the coolant before, and the radiator was replaced under warranty, so figure my coolant has always been well maintained.

I have yet to refill the tranny and coolant pending a few more parts on order, but from what I collected I would say this drain netted about six quarts of ATF, including the tranny fluid cooler drop.

Here are some pictures showing general conditions I found, including the pan, the magnets, the filter I cut open with some shears, and the general appearance from underneath w/ the pan off. Again, this is with one drain already just a few weeks prior.

MP4.2+6.0

Getting out the tranny pan was even more hassle than I expected. My going in assumption is I would pull the ATF cooler just in front of the tranny, plus the couple of cross braces under there to open up enough room. I was draining the coolant anyway, and I open the cooling system in the same area (plus the lower radiator hose of course) to drain more out. A bit more tranny fluid came out from the cooler, though less than I thought--less than a pint. I think the W12 (and S8) have the ATF cooler, but probably not on the 4.2's.

By the time I got the pan out (barely), i had also pulled the driver's side mid exhaust from the back to the downpipes to the next section back, plus a plastic piece inside the filler area of the pan (related picture below). I wasted a bunch of time getting out the T27 Torx bolts around the pan above tough-to-reach areas above the exhaust that were a lot more visible and reachable w/ the exhaust out. It still just barely came free with some levering (hands only) of the now loose downpipes on one side. By pulling the plastic filler piece and pulling the back of the pan downward I was able to slide it forward where I had pulled the ATF cooler and get it out. Afterward, I decided just to pull the other side of the exhaust, as well as the gear oil cooler. The latter was optional, but I should have just pulled both sides of the exhaust right away in any case.

I got the pan back in with all these parts now removed. It still was a challenging fit, and I had to leave the plastic filler piece off until I got the pan into its general position above the head pipes. I also put the gasket in place only at that point, which took about 20 minutes to position carefully. Tight clearances and quasi blind as I worked it around that same filler obstruction in the pan, and the valve body that hangs lower around much of the pan area.

Below is a picture of that plastic insert inside of the pan. It is detachable (with care), and with it in place, it reaches up so deep into the lower tranny area recesses that the pan can't be moved much laterally. I think it's there as a safety device to avoid sticking a fill tube way up to where parts may rotate. On my C5 4.2 w/ the older five speed AT, it didn't have a piece like this, and I remember w/ the pan off I would see up into the back of the clutch area from below at just the right angle. The picture is from the rear of the pan with it hanging down--the inner two of the four W12 downpipes can be seen w/ exhaust unbolted, and you can see the green gasket I'm working into position when I snapped the pic.

MP4.2+6.0

As part of this, I also went after the gear oil in both the front and center differentials. First step was to open both filler plugs. The front diff isn't that hard going in from just in front of the right (U.S. passenger side) front axle, but the center Torsen one is harder to reach, at least with the tight exhaust confines of a W12 (or S8). With the exhaust out it became practical. The fill port is just slightly offset above and about 3/8"/10mm behind the large saddle brace that crosses the drive tube area. Using a 6MM ball end allen wrench--actually one made for electrical sub panel work!--I was able to get it open. With both fill ports now open, I proceeded.

I looked carefully again, and there just plain is no obvious drain for either differential. I looked in Bentley and at EKTA parts diagrams and reached the same conclusion again. That left the gear oil cooler. It is the low spot gravity-wise for the whole set up. I pretty much knew on mine the two diffs were inter tied fluid wise through the cooler, and the internal side shaft drive tube that goes back to the front diff. Now with the exhaust out, I realized the two fluid lines covered with the Audi heat resistant type shiny foil covered insulation are visible up in there too, also confirming it is the single shared fluid system.

FWIW, apparently this set up is on at least some 4.2's, so if you can see those lines and find an oil gear cooler under there (right under the front of the tranny housing in front of the pan), it should be this shared fluid type. What that in turn means is you use the magic (and more expensive) gear oil for the Torsen unit throughout both diffs. It also means pulling the (easy to remove) cooler is a drain point, if you already drained the coolant that is. If you go by the ZF tranny parts and service guide, for refills you can just use the regular gear oil otherwise used in the front and far rear diffs, but I figured I would just go by the Audi "book" here.

I have yet to fill the diffs, but I pre-filled the cooler with the gear oil before bolting it back up after I got the tranny pan back in. That took maybe a cup+, but important I figured in the overall fill since you have to get both "sides" up to the fill overflow point, and once I have the exhaust in again, reaching the Torsen fill port later will be more challenging. I'm tracking fluid use (takes a bit over 2L total) to be sure I get in what seems like all I drained. I need a few more gaskets to complete the job, so am taking my time with draining, filling, bolting parts back in, etc. in the meantime.

JohnnyJ A6Q

[QUOTE=MP4.2+6.0;Below is a picture of that plastic insert inside of the pan. It is detachable (with care), and with it in place, it reaches up so deep into the lower tranny area recesses that the pan can't be moved much laterally. I think it's there as a safety device to avoid sticking a fill tube way up to where parts may rotate.[/QUOTE]

is not that the plastic fill tube itself, meaning it has to be that tall to fill to the proper level ??

if it was shorter then the fluid would overflow sooner, no?

MP4.2+6.0

The extension part would have to be in there to get the level correct, but obviously they made it removable and separate for some reason. It probably adds an inch give or take to the fill height and closer to 2" for the overall height of the piece including the top "hat" of it. The older pan on my C5 4.2 was just a straight up round passage with no "hat" to the top of the cap area; probably was cut down in length and the removable part added for the moving parts safety issue and this removal issue with the challenging exhaust interference.

Removing that plastic extension--just a press on pressure fit--turned out to be critical to get the pan in and out in the W12. Only with both the mid exhaust out AND the downpipes/cat removed would it be a straight vertical shot for the pan.

MP4.2+6.0

Or, "just like downtown" as we used to say.

Hmmm, stupid offset fill plug on rear of center Torsen diff. where a big aluminum cast saddle crosses over, helps support the tranny and has an important exhaust hanger attached to it. I tried screwing the diff. drain plug in with my handy Klein 6mm ball end allen (how I got it out), but no go in any easy way, and no way I was going to cross thread. Bentley says support the back of the tranny/diff at a jack point you see below in the center left edge of the pic, push it up a bit and remove saddle. More shop make work, let alone the tools or any risks. On to the next idea.

So, out came the Makita and presto, see the picture. Good for life of any remaining drains, but more importantly the re-check once I get it running and the gear oil circulating to find its final level given the split center and front common diff gear oil supply. I cannot imagine trying this w/ the W12 (S8) exhaust in place given I couldn't even hold the plug to the fill port with my fingers--I now load it onto the allen tip protruding through the saddle casting before raising it up and screwing it straight in.

Also BTW, jeez, you would think Art over in Engineering would have thought of this given the unused hole right next to it in the casting that only goes halfway through, or the various other 8mm threaded points to which nothing bolts. Maybe if it wasn't obvious to Art, I'll go with that argument of "obviously not obvious to Art," patent it and offer a license for say $175K or one new D4 W12...

mishar

Well done. I remember that one well. But Art doesn't need it. Art has oil for life.

MP4.2+6.0

Just for posterity, Audi has the wrong part number for the center (Torsen) diff fill plug, apparently worldwide from my finding the same bad part number on Euro EKTA. If you order one, they send you what is just a second front diff plug. Only if you order the "old" D2 plug do you end up with the correct part. They are different diameters on the threads--smaller on this center one, and a 6mm allen instead of an 8mm like the front one. On the third order go around AudiUSAParts likewise confirmed that the pics in EKTA don't match the D3 tranny (at leas W12 flavor) back on the Torsen tail end, and that the part # is indeed no good. The difference between the two turns out to be an "A" at the end of the number.

MP4.2+6.0

I did the third and final intended ATF drain on the D3 W12 over the weekend. Some notes:

1. Basically it drains about 4.5L if you just open the drain port and don't pull the pan filter. I drained 7+L for the second cycle where I did pull the pan and filter, plus dropped the W12 ATF cooler. By my math it took 3 drain cycles, one involving a pan pull, to get to a 90%+ cumulative change level. My W12 always ran "blue" fluid/LifeGuard 6+, but anyone switching from Gold (6) to either Blue (6+) or Green (8) would probably want to get to that 90%+ level, and thus three cycles. That means 16L of fluid, which also ties off exactly to the principal TSB that reads on thorough tranny fluid changes--the "hoot" one. IIRC, two drains, one involving a pan pull, got me near 85%; probably good enough absent a change in fluid type. The pan pull is way more work than the simple drain, at least with the W12 (and S8) exhaust interference issues. As one more tidbit, after drain and restart it takes 2-2.5L more once you start the engine. So with a simple drain and refill, likely a majority of the fluid you replace only goes in after you restart it rather than during the first part of refilling right after you close the pan drain up.

2. Using both a Fluke IR thermometer and VAG COM together, I found the simple Fluke IR measure pointing the laser dot at the pan area underneath gave me essentially the same reading as the VAG COM when looking for that 40-50C sweet spot to check it for final fill level. But a lot easier when you are under there to just hit it with the IR gun than fumble w/ a laptop, especially if you do it solo.

3. I ran the tranny adaptation afterward. Surprisingly, even though VAGCOM has an adaptation button, I didn't see it there anywhere below that choice. Instead, IIRC by looking at another adaptation first (throttle or engine??), by using Basic Settings and resetting the very first block that comes up to 00, it seems to have triggered the adaptation cycle--meaning it wiped all its prior shift behavior learning. Later I noticed you can do that under "Adaptation" too, but it isn't documented there like it is for the Engine module. Per various stuff I've read, neither code resetting nor power disconnecting results in a fresh adaptation. Then following a TSB set of instructions I did an adaptation drive. Results seemed good. Adaptation following forcing the reset is basically some shifting from neutral to drive and then reverse to drive for three seconds 5x over, then some 1-2 and 2-1 shifts (using the manual mode) and then a bunch of driving where you slowly run it up from 1 to 6 and back down from 6 to 1 again a bunch of times while in regular automatic for a mile or so each time. It took a quiet nighttime boulevard or two where I could reach 45 or so and get it up to 6th (on a low revs/high gearing W12) and then slowly come down without pissing off other drivers or looking extra odd on the road and with shoulder coasting/ slow stopping. The before, during and after shift quality seemed better at the margin as the adaptation drive progressed. Subtle, but on a quiet road w/ no tunes, AC blower, and with very careful feel and listening, I could sense little stuff like torque converter locking cut in or out in higher gears, smoothing out of the shifting, etc. Still haven't jumped on it or tried hard to make it act up in any way, since adaptation instructions say it is up to 500 miles to fully settle in to its new parameters, and I haven't gone hardly 50 miles since so far.

4. The ATF fluid still looked pretty murky on the second and single biggest drain with the pan pull. Only on the third drain could I see some color to what I was draining, though it looked more greenish as it drained than the nice bluish I was pumping back in.

PaulW

Interesting regarding adaptation. Where did you get the instructions for that?