I've had this '00 Passat 2.8L ATQ 4motion for months. I bought it with a bad engine. I got one from a '01 A6. Since I swapped it in I've had problems starting it. See my video.
It appeared to be an engagement problem. It looked like it wasn't fully engaging the teeth on the flexplate... The old flexplate was damaged from the starter. I got a new starter and a new flexplate.
HOWEVER, look at the pictures with the started bolted to the engine. The starter would never be able to fully engage the flex plate.
HELP! What is going on!!!???
The last picture shows the cone of the starter essentially rubbing against the flexplate.