Automatic Transmission AFN: Oil Change, Gearbox.

Hello,

Unfortunately, I couldn't find anything precise on this topic.

Here's the translation:

'I'm having a problem with my AFN automatic transmission (transmission code DAB), manufactured in 1996. It appears that transmission oil is leaking into the driveshaft. The issue is that there's approximately 200-300 mL less oil in the transmission, but there's 200-300 mL too much oil in the driveshaft, and I can't find any visible leaks.'

As far as I can tell from my research, this transmission and car use the same type of automatic transmission fluid (ATF) for both the transmission and the axle drive.

'For some time now, it seems like nothing is draining out. There's simply too much oil in the rear axle differential. The transmission oil level is correct. Otherwise, the car runs and shifts well (for now).'

My question: Is this condition harmful to the rear axle? Or is this the beginning of the end?

Because the cost of repairing it will probably outweigh the benefits...

Thank you in advance for your suggestions.

Best regards.




Golf III TDI, 1.9L, Automatic (DAB).
265,000 km (manufactured in 1996, model year 1997)

The only (and frankly, far-fetched!) scenario that comes to mind is that the excess oil might be whipped up into a foam by, for example, the gear ring of the balancing gearbox, thereby impairing the lubrication. But I think that's highly unlikely...

In principle, the extra 300ml shouldn't cause any issues. It should be noted that up to production date 24.08.2006, both gearboxes used ATF fluid. From 25.08.2006 onwards, the transfer case uses SAE 75W-90 fluid! (75W-90 and ATF are not compatible, so make sure you actually have a "2x ATF" gearbox).

OK, thanks. I'm pretty sure about the 2xATF, since the transmission must have been built beforehand...

So far, I haven't read about any major or negative experiences regarding this topic. However, I would be happy to read about anyone else's experiences!

Hello,

Okay, in ZF automatic transmissions from the year 2000 onwards (or possibly even earlier, although I'm only familiar with this system from newer models), separate fluids are used. This means ATF (Automatic Transmission Fluid) is used in the transmission, and SAE 75-90 is used in the differential/axle drive. However, I only know about this system. I can't say whether the differential was also filled with ATF in older models. But, as described here, it's likely that it was.

But to get back to the topic of gearboxes with separate oils (ATF and 75-90).
If there is any sign of oil mixing between the automatic transmission fluid (ATF) and the differential/axle lubricant, immediate action must be taken, as otherwise the differential will be damaged! ATF is NOT compatible with 75-90 oil!

To prevent this, ZF has installed a hole in the transmission housing. If there is a leak between the two parts (which are only sealed with a single oil seal where the shaft passes through), the oil will be directed into the transmission housing, and from there it will drip onto the floor between the engine and the transmission.

Here's the translation:

"For example, it doesn't always have to be a seal failure where the transmission oil leaks out between the engine and the transmission. It can also intentionally come from a leaky differential seal to avoid causing greater damage to the differential. "

You can find this, for example, in the 5-speed HP 19 transmissions, etc. (V6 TDI, Passat, etc. with Tiptronic transmissions).

Perhaps this will help you understand how the system is structured a little better. Best regards.

Okay, as I mentioned, I'm quite sure that my rear-wheel drive system uses ATF. The year is 1996, and the transmission is a DAB 01MB.