A8CT

I just found this one another site from '07....
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Hello, Transmissions, transmissions, transmissions. To those of you that have replaced your transmissions here is my story. I'm a Porsche mechanic by trade, 356 version not the new ones. My wife calls me at work one day and says her 98 A8 with 110,00 miles on it will not move when put in gear. I go home and try it and it's locked in gear and won't slip to start off. After a brutal rev and jam into drive I get it to the shop. I change the dirty trans fluid and filter and button it up and it does the same thing, life time fill on trans fluid my ***. Take the trans pan off again and remove the bank of solenoids that do the shifting. Each one has a small filter screen that is CLOGGED with metal! Clean them all out and reassemble and it works like new. Have since driven the car another 90,000 miles and still working like new. When changing fluid drop the pan, do the filter and pull those solenoids. I'm thinking a lot of transmissions are being replaced for no reason other than someone not finding the real problem. A happy A8 owner.

TOMAS7

BTW, check your email.

tozoM8

1; The fluid that goes into the valve body has to go trough the tranny filter. There are two more filter inside the VB.
The only way for metal particles to get to the pressure regulator valve if something is broken in the VB. A simple cleaning would not fix the broken part(s). If the particle is big enough to clog the filter, it would stuck the valves before it goes to the PRV. The VB need a complete dis-assembly to free up the valves. A simple PRV cleaning would not help.
2; Each pressure regulator valve controls a different fluid line(circuit). They are not connected to each other so contamination would not travel to other PRV.
3; I've never seen an A8 with 200K miles that drives like new.
If someone decides to clean the PRVs, make sure they go back to the same location. They are calibrated to each fluid line. The tranny would not work properly if they are mixed.
<img src="http://pictureposter.audiworld.com/80919/dscn1033.jpg">

TOMAS7

^^^^^^Thanks a million tozoM8!^^^^^^^