I searched through 20 pages on the forum and found similar posts and threads but nothing to answer my queation. Google as well. Looking for an engine for my 01 Jetta and found a 99 Passat wagon 1.8 and I'm wondering if that's doable
I'm not sure, but I think not. The Jetta engine, while similar, is intended to be mounted transversely. It would be a lot of refitting to make things connect, at best. And if you care, it's technically illegal to mount an engine older than the car. Some emissions thing.
It could be done, but it would be a hassle as they use a different block. It would be better to use an engine from the later 2001-05 Passat as they have the internal water pump like the Jetta and also have the DBW and SAIP setup. You would need to swap over all external flanges, mounts, coolant and oil lines as well as manifolds and turbo.
For motor swaps, it depends on the state. Some states do not allow older motors to be swapped in, but unless the motor has different emissions equipment, they will never know.