ATF Leak at Transmission Solenoid Harness Entry
 

First, I've been a long-time reader but am a first time poster. I've learned a lot on the forum and appreciate everyone's input.

Now my question. I've searched the archives but haven't been able to find a previous, similar post.

I have a 1998 A8 4.2L Quattro. I noticed that the transmission has slipped a bit as of late and also went into limp mode a few times in the last week or so. Threw code 17114 Gear Incorrect Ratio. Hoping for the best, I ordered a filter, ATF change kit, raised the car and dropped the AT pan tonight. After dropping the pan, I noticed that the coupling on the front of the transmission housing through which the solenoid harness enters was wet with, presumably, ATF. I felt the plastic coupling and it is loose. I assume that it should be tight and the fact that it is loose is causing the ATF leak, and my slippage problems.

Has anyone else encountered a leak in this area while changing the ATF?

Also, while I'm in there, I thought about removing the solenoids and cleaning them, in case they were sticking and contributing to my problems. Has anyone done this before? Any words of advice?

I'll post my progress as I go. Thanks in advance.

No i have never seen a trans leak from there, but thats definately causing your slippage problems. On another note, if you don't have a vag com or the specific VAG fill tool you will most likely screw up the fill procedure. There is no way of removing the solinoids to clean them, and that really won't do anything to help you. I would figure out what parts you need from the dealer to plug the leak, and have them fill it for you. Unless you have experience with ZF transmissions and you're armed with a vag com to monitor the transmission temp.

Thanks for the input, auditech. Your posts are always very helpful. I've ordered a VAG cable and plan on downloading the ross-tech software to monitor the temperature (30-45 C, I believe). I drained the fluid last night and plan on filling it tonight. I’ve been following the audipages ATF instructions, which indicate that with the car running it should take about 15 minutes for the temperature to go from ambient to 45 C, so I assume that is my window to fill it and go through the gears a couple of times to get to the right level.

My drained fluid was dark brown, but not yet black. There was some smudge on the filter and pan, but not as much as I suspected. There were no magnets in the pan. It looks like someone changed the ATF previously (I’ve only had the car a short time) as the gasket seemed newer and some of the T27 torx screws were replaced with standard 10mm bolts (the ones under the exhaust, fortunately).

Regarding the leak, I’d like to be able to remove the plastic solenoid harness coupling for inspection. Has anyone removed this piece before? Does the solenoid harness terminate at the coupling, or is it a pass-through only? There doesn’t appear to be any sort of gasket between the plastic coupling and the transmission case, which surprised me. I’m wondering if there should be a gasket of some sort there, and the fact that there is no gasket is causing the leak. I couldn’t find any exploded views of the transmission showing this piece. Any info on this would be much appreciated.

When I pulled the ATF filter, I noticed that it had been damaged. There is a black plastic tube that protrudes down from the filter, I assume to siphon AFT from the bottom of the pan and through the filter. On my removed filter, this black plastic tube was broken such that there were three jagged “V” shaped breaks in it, about one inch deep by one ¾ inch wide at the bottom of the tube. I’m thinking that the change in the geometry of the tube bottom would affect its ability to pull fluid from the pan, especially if the fluid was low. Also, I’m worried that those pieces of plastic could be broken up and somewhere inside the transmission, but I maybe that would be prevented by the filter.

As for the leak, after further inspection I think that it wasn't leaking at the coupling after all. I took the coupling apart and it's not quite completely sealed, but is designed to keep most of the fluid in. I'll continue to monitor it for a bit to see if it changes.

Back to the transmission: I filled the fluid today following all the requirements (temp, level, going through gears, OEM fluid, new filter/gaskets, etc) and then took her for a ride. No change in the problem, still not quite shifting right. I did some experimenting in Tiptronic and seem to have narrowed down the symptom. It seems to only slip up in 2nd gear. It's more of a clunk where it feels like it's trying to shift, but it happens in 2nd gear in manual shift mode. All the other gears seam fine. It also shifts fine through all (except 2nd) in auto mode. Could this be a symptom of something else? Torque converter, perhaps?

How were you filling it? You only have like a 10 minute window to get all of about 6 -7 liters in there before it gets too hot and expands on you. Did you get your vag com yet? Is there any fault codes in the TCM like a shift solinoid etc?
The fact that the filter had something broken worries me, it wouldn't get into the clutch pack area, but it could clogg/block a check ball in the valve body causing shift problems on one gear. If you had a bad torque conveter, usually you will get a check engine light and have faults in the ECM, and TCM.

I started filling it cold (it had sat overnight) and timed myself from when the car was started to when I finished filling it. I put in 6 liters of fluid in 10 minutes before it started spilling out. I had a friend in the car who cycled each gear for about 30 seconds twice while I filled it. The last cycle he only stayed in reverse for a few seconds because it started spilling fluid out while in reverse. I haven’t received my PC cable yet so I wasn’t able to monitor the temp. I plan on putting it back on stands later this week once I get the cable to double check the fluid level at the appropriate temp.

I did pull a transmission code using a generic reader. Code 17114 Gear Incorrect Ratio. Also 17087, but I read somewhere that is for not having the brake pedal depressed. No engine codes present.

One more piece of info. While driving it the first time after the fluid change, after it clunked/hesitated in 2nd gear, after it shifted into 3rd gear I heard a squeal that I had never heard before. It was fairly loud and sounded kind of like I peeled out the tires, but I don’t think the tires peeled out. It also seems to be a little more doggy, not accelerating as well as before the fluid change in lower gears (1-3). That could just be in my head since I’ve been trying not to accelerate too quickly since the fluid change. 4th and 5th gear seem fine and power/acceleration seems fine in those gears.

Since the fluid change, it frequently cuts to safe mode (all gears lit up) when starting from a stand still. It did this a few times before the fluid change, but it’s been more common since the fluid change.

Thanks again for your input.

That code is from running through the gears up on jack stands without turning off the ESP. You only have to cycle through the gears once, then put it back into either park or neutral when filling it. It is absolutely crucial to use a vag com here. I cannot tell you how many times people would swear they did it right and i fixed the car by doing it for them. It has to be perfect, putting it into reverse could have caused problems at the very end.
The fact that its going into trans limp mode (all gears lit) tells me its not correct.

Thanks for the feedback. I’m hoping that I did it wrong and that it’s not something major. I should have the VAG-COM cable this week, and I’ll download the ross-tech software so I can monitor the fluid correctly. Here’s what I intend to do, please let me know if I’m missing any steps:

1. Let car sit overnight to cool down.
2. Plug in VAG-COM w/laptop set up to monitor temp.
3. Remove fill plug w/17mm allen.
4. Turn on car.
5. Begin pumping in fluid until pan overflows.
6. When temp is at 35C,shift through all gears, starting with reverse, then through D, 4, 3, 2 and then end in Neutral, all the time adding fluid.
7. When fluid stops overflowing out of the pan, replace the fill plug.
8. Shut off car.

Please let me know if that’s the correct order or if I’m missing any steps.

Thanks again for your help!

No thats incorrect, do not run the engine when draining the trans. When you hit 35C you are at the limit and this is when the fluid will expand beyond spec. You have to fill the trans with about 4 liters, then start it, run it through the gears, then continue filling until you get to about 32C. If you have already put in 6 liters by this time, wait until it hits 33C and keep adding until it spills out. If you hit 35C your fucked.

I'm sure you get this a lot on this forum, but man, you're a genius. I got my VAGCOM cable today and followed your steps exactly, topping off the fluid at 33C. It drove MUCH smoother and shifted much better. Thanks for your replies and help. I cleared the codes and will monitor them to see if they return.