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Good Day all. I purchased an A8 with a spun rod, replaced the motor and now am having some issues with the transmission. When the motor was first replaced, there were some slippage issues with the transmission, which I resolved with the addition of fluid as some was expelled from the trans cooler lines when we replaced the engine. I was able to get all gears with no codes and car moved fine, although I never drove it more than the driveway and down the block.

We spent a long weekend out of town, and I parked the A8 in the garage. Upon return, I was unable to engage any gears, and if engine was revved while in gear, the trans would go in Limp mode and entire gear selector would light up.

Rather than wasting more fluid, I decided to replace the trans filter. We successfully replaced the filter and started to refill the trans with fluid. After about 4.5 liters, it started to overflow, so we started the car to pull fluid up into the trans and cooler, but wouldnt pull any of the fluid.

When running through the gears, it sounds as though it is engaging and the engine revs slightly when going into gear as normal, but even on stands, there is no movement.

I have not been able to pull the codes yet for the limp mode, but what is most concerning is that no fluid is pulled, leading me to believe it is pump related. We have pulled TCM harness, with same results.

I have read some material on the F switch causing issues where it sounds as though it is engaging but car remains stationary, but the fluid issue I believe eliminates that possibility.

There was no whining or odd sounds prior to failure, it simply worked, then didn't 2-3 days later on next startup.

Any thoughts would be appreciated.

Thanks.

 

I'm not sure if tranny-related topics are covered or not, but check out audipages Home - there's a decent amount of A8 specific info there.