There has been a fair amount of discussion recently about problems that forum members have encountered with the 6 speed transmission that is installed in the V8 powered Phaeton. Although we have not yet figured out exactly why these transmissions are encountering problems, most of the evidence appears to point towards contamination of the transmission fluid with engine coolant. This could be taking place at the heat exchanger at the front of the car where the transmission fluid is cooled.
After reading all the discussion at this thread V8 Transmission Problem (was: Engine Coolant in Transmission Fluid), and reading the truly outstanding write-up by Barry Lenoble and Paul Waterloo of AudiPages forum explaining how to change the automatic transmission fluid in an Audi that is equipped with a similar transmission, I decided it might be a good idea to change the fluid and filter in my transmission. I have a W12 powered Phaeton, which uses the 5 speed ‘FGE’ transmission. I have not encountered any problems of any kind, I just decided to do the fluid change partly as preventative maintenance, and partly because I wanted to see what was inside the transmission.
The illustrated guide at the AudiPages forum (Audi A8 Transmission Service) is the basis for this post of mine. The process of changing the fluid in a Phaeton transmission is almost identical to the process for an Audi.
There are two important caveats that must be considered if you are planning to change transmission fluid in a Phaeton:
a) You absolutely must have a hydraulic lift to raise the car. There is a subframe support bar installed right across the middle of the transmission pan. I think the torque specifications for the bolts on this bar are one million Newton-meters per bolt. I cannot imagine being able to get this thing off without the car being lifted up nice and high to allow you free access to it.
b) It is really, really difficult to get the transmission filled up (from empty) before the transmission fluid temperature exceeds the 35°C limit. For this reason, you have to plan to drop your car off at the VW dealer early enough in the day to allow the staff to drain the fluid and partially refill the transmission, then leave the car sitting up on the lift overnight (to cool down) before making the final filling and check first thing the next morning. I cannot over-emphasize how important this is… the car needs to be left on the hoist overnight to cool down before the final check is done.
Having said that, here is a photo essay that describes the process. Please use this together with a printout of Barry and Paul’s write-up from AudiPages – I have not attempted to re-state everything they have already documented there.
1) You will need to order the parts in advance. For a 5 speed FGE transmission such as is installed on a W12 powered Phaeton, this is what you will need for consumables:
1) 9 quarts of fluid suitable for a 'FGE' transmission – part number G 052 162 A2. This is a light amber colour fluid, it looks like Drambuie, has about the same consistency as Drambuie, and costs about as much (per liter) as Drambuie.
2) A gasket for the transmission oil pan, part number 01L 321 371. This is the large green thing.
3) A washer for the drain plug on the transmission pan, part number 018 321 377 B. It’s not possible to order the washer by itself, in practice, you order a new plug and washer.
4) A washer for the fill plug on the transmission pan, part number 01V 321 379. This is actually a rubber O-ring, not a washer, but the parts catalog lists it as a washer.
5) A gasket for the fitting from the oil strainer to the valve body, part number 01L 325 443. This is also an O-ring. Do not get it confused with the other O-ring, they are about the same size but they are not interchangeable.
6) An oil filter part number 01V 325 429 C. This is a flat metal assembly – the filter element is hidden inside it.
You will also need some unusual tools. These are well described in Barry and Paul’s write-up. For a Phaeton, there are three additional special tools that I think you should have available – a hydraulic lift for lifting up the car, a Volkswagen dealership for protecting the hydraulic lift from the elements, and a VAS 1924 transmission fluid filling device.
How to do the work – Draining and Disassembly
Lift the Phaeton up on the hydraulic hoist. Observe the lifting precautions detailed in this post: Lifting the Phaeton on a Hydraulic Lift - Precautions.
Remove the two plastic underbody pans. The front pan comes off first, the rear pan comes off second. You cannot get access to the transmission without removing the rear pan.
Remove the subframe support bar that is present underneath the transmission. I am not sure exactly what this bar does, but I think it adds rigidity to the front suspension. There are nuts on the top of the bar – you will need a socket wrench with an elbow of sorts to allow you to hold the nuts whilst you remove the bolts from below.
Once this bar has been removed, you can remove the drain plug and the transmission fluid will come out. It does not matter what temperature the fluid is when you drain it.
Once the flow of fluid from the drain plug has slowed down to a dribble, you can begin to remove all the fasteners from the perimeter of the sump pan on the bottom of the transmission. These are Torx 27 head fasteners. There are a lot of them – over 30. Same as is illustrated on the AudiPages post, you will have difficulty with two being slightly obstructed by a muffler pipe. The work-around is the same – grind a T27 socket down, then put it in a ¼ inch box end wrench and access the two problem fasteners from the side. It is easiest to leave four fasteners (one on each side) in place until after you have removed all of the others. Then, support the sump pan with your hand, and have a helper remove the last 4 fasteners. The sump pan will have about a liter of fluid in it when you remove it – keep the sump pan flat as you remove it, otherwise you will get soaked by the residual fluid.
The transmission will continue to drip fluid (slowly) after you take the sump pan off, so keep the waste fluid drain device handy to roll into position under the transmission after you have taken the sump pan off.
I observed the fluid as it came out of my transmission – it was a translucent brown colour, much the same as the new fluid. I caught a bit of it in a glass container and let it sit for a while. There did not appear to be any evidence of contamination by any other fluid, or cloudiness, or anything else amiss. No sediment appeared to settle in the bottom of the glass. My car had about 30,000 miles (actually, 54,000 km) on it when I did this.
I had a look at the inside of the sump pan and the magnets in the sump pan. There was a very fine paste-like substance on the magnets, but no obvious metallic particles. I think that the paste-like substance was probably material that had worn off of the various clutches inside the transmission and was then caught by the magnet. There was a tiny bit of sediment on the bottom of the pan, but not anything that I or the techs at the VW dealership were concerned about. All in all, the fluid looked like it was in good shape, and there was no evidence of excessive wear to be found.
Below is a close-up picture of the magnets in the bottom of the tray, and a wider photo of the entire tray. These magnets are located prior to the filter in the fluid flow sequence – so, I am not too worried about the very fine paste on them. I think this is pretty typical wear, and it is similar to the ‘fuzz’ that is found on the chip detector magnet in a healthy aircraft turbine engine.
The next step in the process is to remove the filter, which is the large flat black rectangular thing in the photo below. This is accomplished by removing the two fasteners that hold it in place. I did not bother to tear the filter element apart because there was nothing found upstream of it to warrant further inspection.
Once the filter has been removed, all the draining and dis-assembly work is complete, and the re-assembly phase begins.
How to do the work – Re-assembly
Fit a new O-ring onto the new filter. See the three photos below. Moisten the O-ring with fresh ATF before installing it, and take care not to twist (deform) the O-ring when putting it in place. Install the new filter – it is a friction-fit into the hole on the bottom of the transmission – and put the two fasteners that hold it back in place. Be aware these are different than the fasteners that hold the sump pan in place. The torque value for the fasteners that hold the filter in place is not specified in the VW repair manual, so I used 11 Newton-meters, (8 foot-pounds), which is the same as the torque value for the fasteners used to hold the sump pan in place.
Re-install the drain plug. It is not possible to purchase only a gasket for the drain plug, so I purchased a new plug, complete with gasket. The torque value for the drain plug is not given in the VW repair manual. So, I just torqued it until the threads stripped, then backed it off a quarter of a turn, which is standard practice if you are not certain about these things.
Place the new gasket over the flange on the sump pan. Then, lift the sump pan up and put one fastener in each side, but do not tighten the fastener – leave it loose with about 1 cm of thread showing. Now install all the other fasteners, again not tightening them, leaving them with about 1 cm of thread showing. Once they are all in place, gently press the pan up from the bottom, and finger-tighten one fastener on each side to hold the sump pan and gasket up against the bottom of the transmission. Then tighten all the fasteners, using a diagonal work pattern, to a value of 11 Newton-meters (8 foot pounds). It is very important that the torque is equal on all the fasteners. The VW repair manual does not give a torque value for these fasteners, but VW of America technical bulletin 00-06-06 gives the value of 11 Newton-meters for these fasteners.
Once the sump pan has been reinstalled, you can remove the filling plug. Do not install the new O-ring on it as soon as you remove it - save the new O-ring until the end of the whole process, because you will be installing and removing this plug a few times before you are finished. Keep the fill plug handy, with the very large Allen key installed in the bottom of it – you will need to be able to get access to the plug and the Allen key quickly later on, to avoid a big mess when you are filling the transmission.
Before you forget about it, re-install the big subframe support bar that goes across the bottom of the transmission sump pan. Take careful note of how it is oriented – the beveled part in the middle is installed so that it matches the shape of the transmission sump pan. The bevel goes on the top, and faces the back of the car. The torque value for these bolts is interesting – it is 50 Newton-meters plus an additional 90° of tightening. In other words, pretty darn tight.
How to do the work – Filling it
Now it is time to start adding new transmission fluid. Fill up the VAG 1924 transmission fluid filling jug with the fluid appropriate to your transmission. In the case of a 5 speed transmission model FGE, this is VW part number G 052 162 A2. I believe that the 6 speed Phaeton transmission uses a different fluid. Double check to make sure you are putting the correct fluid in the transmission.
Hook up the diagnostic scan tool (VAG 5052 or similar) to the car, and look up the measured value block for ATF temperature. This is MVB 1 of group 7. If you prefer, you can use guided functions.
Place the jug in a convenient and secure place that is well above the transmission. On a Phaeton, the air intake area behind the engine is big enough to offer an excellent spot for placing the jug. Gravity will then do the work for you.
Be very cautious and gentle when inserting the filling tube. If you reef it in too hard, you will damage the top of the filling hole assembly.
Get everything organized and the diagnostic scan tool hooked up before you begin filling.
Place the jug on the top of the engine, then lift the car up, stuff the nozzle into the filling hole, and open the valve. The transmission will accept about 4 liters of fluid before it starts to spill out - see the photo below.
When it starts to spill out, remove the nozzle, put the filling plug back in place (finger-tight), and start the car. Run it through the different gear positions (don’t bother with S, that is just an electrical position), then turn the engine off and put the nozzle back in and continue filling. It will probably take another 3 liters or so.
Don’t leave the car running longer than necessary to stir things up inside the transmission, otherwise, the fluid temperature will increase beyond 35°C, and then you will have to leave the car up on the lift overnight to cool down and re-start the process in the morning. In practice, I have never been able to get this job finished without the fluid temperature exceeding 35°C before I am finished, so, you might as well plan to leave the darn car up on the lift overnight and finish the job in the morning. Life is less stressful that way.
This is what the diagnostic scan tool looks like when you are monitoring the temperature of the fluid as you fill the transmission. Once the temperature gets to 40°C, you need to leave the car turned off for quite a while (overnight is easiest) to let it cool back down again before you can do the final top-up.
To complete the final top-up, start the (cold) car, run it through the various gear positions (Park, reverse, drive, 2, 3, 4, 5) for about 20 seconds each, put it back in park, take the plug out, and fill until the fluid leaks out. This is done with the engine running! The objective is to have the fluid leaking out just as the temperature of the fluid reaches 35°C. At this point, put the filling plug back in, tighten it to 80 Newton-meters, and take the car for a long test drive so that everything gets hot. Bring a portable diagnostic scan tool with you and make sure that the transmission fluid reaches at least 85 degrees. This is the point at which the valve to the transmission fluid cooler (at the front of the car) opens. Bring the car back to the dealership, let it sit for about 5 hours with the hood up (to help it cool down), then perform one final fill. At this point, the work is done.
Note that the transmission will not require addition of the full specified capacity of fluid (9.8 liters) because you have not drained all the fluid from the torque converter or the transmission fluid heat exchanger during the drain process. My transmission accepted 7 liters of fluid – this does not include the roughly 500 ml that was spilled during the various top-up sessons.
If you have read this far, I think you can now understand why you need to leave the car at the dealership for a couple of days to get this work done. The most time-consuming thing is letting the fluid cool down.
Below is a picture of a Phaeton that is at the ideal temperature to begin the process of adding transmission fluid.