Answer
Sep 24, 2025 - 06:09 PM
On the 4.2 V8 in the ’04 Phaeton, you’ve got two little mechanical vacuum pumps that sit at the back of the cylinder heads. Each one is driven off the camshaft.
The left pump mounts on the back of the left (driver’s side) cylinder head, and the right pump mounts on the back of the right head. The pump body has an alignment tab that matches the head casting, so you can’t really clock it wrong as long as it’s seated flush and the drive engages with the cam end properly.
Biggest thing is to make sure the sealing surface and the O-ring are clean and in good shape before bolting them back in. A bad seal there = oil leaks pretty quick.
If you want the step-by-step install procedure and torque specs, that’s all laid out with diagrams in this manual, including step-by-step instructions, clear images, and exploded-view illustrations.
