Automatic Transmission Leak: $2000 Repair Cost?

The automatic transmission on our 1992 Audi 100 C4 gasoline engine (V6 2.8 AAH) is leaking.
(4-speed automatic transmission by ZF).
(Otherwise, the transmission still shifts perfectly / mileage is now 149,000 km).

The leak is not located in the area of the "oil pan" of the transmission.
but rather in the area of the rear "housing cover" (which also contains bearings pressed in from the inside, in which shafts run, etc.).

My trusted mechanic is now hesitant to remove this housing cover because he's concerned that the aforementioned shafts might then interfere with something, etc.
I can understand that...

"Automotive specialist companies" that I contacted want to immediately sell me an automatic transmission...
It is said that, otherwise, the cost of removing and installing the transmission, etc., would already be in the range of the cost of an automatic transmission --> approximately 2000 EUR (including everything).

I need an independent third opinion from you all right now:
Wouldn't it be possible to reseal the automatic transmission with less effort?
Do I really need a complete automatic transmission for that?
Can anyone perhaps recommend a company (in the northern Germany region) with experience in the repair and maintenance of automatic transmissions?

Thank you in advance for your opinions...

Hi,

How do you know it's leaking? Is it losing a lot of oil? (It probably shouldn't be leaking if it's still shifting perfectly.)

Quote:

Shouldn't it be possible to reseal the automatic transmission with less effort?

"Exactly where is it leaking? What kind of seal is used in your transmission?"


Regards,
Sure, here is the translation of the text from German to English:

"Micha"

Mephisto wrote:

How do you know that it is leaking?

because it's leaking oil, red ATF oil.

Mephisto wrote:

Is he losing a lot of oil?

Yes.
But only while driving.
If I stop it, only the fluid that leaked out while driving drips out.

Mephisto wrote:

(It really shouldn't be like that if it's still shifting perfectly.)

Of course, I'll refill it...

Mephisto wrote:

Exactly where is it leaking?

On the sealing surface of the rear housing cover.
in the lower area.
approximately where an additional Allen screw is inserted from the front.

Mephisto wrote:

What kind of gasket is in your transmission?

I have no idea how I could find that out.

'Try to find someone who has ASLE installed on their computer, or ask an audio dealer if you can briefly take a look. Everything is usually well-documented there, and it should indicate whether the waveforms are suitable for you if you remove the cover.'

I would try to reseal it. If that doesn't work, you can still replace the transmission with an AT (automatic) transmission.

Is there a guide or FAQ on Erwin (siehe Fehlerdatenbank) where your question might be answered? Probably. You just need to find it.

https://erwin.audi.com

However, I don't know if it's possible without a flat rate, or how much it would cost. Maybe someone here has a flat rate with Erwin (siehe Fehlerdatenbank) and you could take a quick look...

Herr Antje wrote:

Is there a help section or FAQ on the E R W I N website where your question might be answered?

I have both E R W I N and ASLE, thank you...
...but these programs don't solve my original problem (see above).

I'm sorry, I didn't understand that. You're worried that the waves might come towards you. But if you follow the instructions in the guide and disassemble, seal, and reassemble the gearbox, shouldn't that work?

If you follow the instructions carefully, you should be able to get those "leaking" waves back in, right? If it doesn't work, it won't be described. And even if it doesn't work out in the end, which is almost unimaginable, you'll be in the same situation as now and need a rebuilt transmission. Constantly adding oil is probably annoying too.

I always unscrew lids whenever I deem it necessary. If it wouldn't work, there wouldn't be a lid to unscrew. So far, it has worked. And with this stupid comment, you probably haven't been helped either, sorry .

Hi again,

Okay, I've done it now.
It can be done without removing the gearbox.
"You remove some motor mounts, etc., and then tilt the whole thing slightly backward."

Then you can unscrew the lid.

Due to known sealing issues, there is a separate update kit available for the "4HP18FLE" transmission (VAG: "CDT").
This is the VAG part number: 01F 498 811 A.
Es besteht aus 2 Dichtungen (für Deckel und Zwischenplatte -> vergl. Attachment)
and a new breather, which is now made of metal and contains a metal ball (to allow air to escape while keeping oil inside).
There's even a small guide on the subject included.

So far, so good, but now, after a few months, the same thing again .

same location.
A phone call to ZF revealed that they cannot imagine the leak recurring in the same spot with new seals.
I should definitely check to see if it's actually coming from somewhere else and is just being "blown" there by the wind.
"The cover cannot be warped, and the intermediate plate does not need to be designed," replied the friendly and knowledgeable employee from ZF in response to my inquiry.

What could I have done wrong ?
I had previously used a sealant that a trusted mechanic had given me. Could it be that this sealant is not compatible with the ATF oil, or something like that...?
I'm currently at a loss.


Dirk.



"Der schnelle braune Fuchs springt über den faulen Hund."
Vehicle data:
Audi 100, Type C4, 2.8 V6 (AAH), 1993, Front-wheel drive, VIN: WAUZZZ4AZPN022324.
Item 1: 010225
Item 2: 0588
Item 3: 5070283

4-speed automatic transmission (manufacturer: ZF).
Gearbox identification code "CDT".
4 HP 18 FLE with parts list 1050 012 002.
"The quick brown fox jumps over the lazy dog."

DirkC4 wrote:

There's even a small guide on the subject included. I had used a similar sealant before

.

Was does it say about sealant, because it wasn't included, right? I might try installing it without it, if it really comes from the same spot again. I'll also measure the surfaces again to make sure they're flat.

Hello Dirk,
"Because of the extra sealant applied by the mechanic, the seals often slip when tightening the cover. That's why I've already had to replace the valve cover gasket twice in a matter of days."

If the sealant is oil-resistant, it shouldn't matter whether it's exposed to motor oil or ATF.

Perhaps there were still small remnants of the old gasket on the sealing surface, or scratches from removing the gasket?

Could the seal have simply come loose, meaning that tightening all the screws would fix it?

Karsten.