New here. Just bought a couple 98 Jettas that had been sitting in a field for a decade.

[kf6eml]

I saw an ad on craigslist for Jettas at $300. For that price, you know there's major work to be done.
Turns out, the guy bought an auction lot, and the cars were included. He didn't really want them, so effectively sold them for roughly their scrap price. He neither knew nor cared about condition or repairability.
I bought two. A red one and a white one. The combined price was around $600
I took a battery with me when I went to look at them, and the red one actually cranked. The white one didn't, but the body seemed in great shape, so I wanted it.
Many of the cars were in horrible shape. Rodents made nests in every engine compartment. They got into most of the interiors. The two I chose had no evidence of intrusion in the passenger areas.
The red one has major rust damage, and I may, someday, patch it. Maybe. For now, it's the donor car for parts.

The white one is in better shape. Probably needs some suspension parts, and I've posted about some problems I've had with it.

It had rat nests in the engine, when I got it. This photo is after I had already removed about 5 grocery bags' worth of material:

After a little bit of work, (okay, a whole LOT of work,) I drove it over to a friend's house to use his pressure washer.
It cleaned up nicely!

(That's my '13 Passat (TDI, of course!) in the background.)

 

[kf6eml]

The guy who sold them had 10 in total. All I know is that they may have been part of some research project, and after the project was over, they were left in a field for about 10 years before they decided to include them in an auction lot that had a bunch of other items. I have no idea what may have been researched. There were no modifications that I could find, except for a glow plug mod that I wanted to do, anyway. I'm guessing the relay went bad, and they just put in a push-button. Therefore, it was probably some alternative fuel research. I don't know, I don't care. The fuel in it looked and smelled like diesel, to me.

After cleaning out the engine compartment, I found that the starter plug was disconnected, which is why it failed to crank. It had no detectable oil, so I put in some "lightly used" (about 5K miles) oil from a friend's diesel Jetta, and cranked it. It turned over, but I could never get fuel at the injectors. So I swapped the injector pump from the red car into it, and it worked. I only had to swap the inlet relief valve because of a bad O-ring.
The starter also got swapped. I guess the torture test of cranking the engine trying to get fuel to flow was too much. It would engage, but immediately disengage without cranking much. I'll see if I can get it to work, later.

Rodents had chewed off a number of wires, so I did have to make some extensions. Thankfully, there was just enough wire left at the connectors that I could solder on some wire that I have lying around. They also chewed off some hoses, but I have the majority of them either patched or replaced.
They also ate the grille over the fresh air intake and nested in the cabin air fan. I sucked out everything I could with a shop-vac and swapped the undamaged grille out of the red car. When I turned on the blower, a lot of dust came out. It seems to have cleared out all the stuff the shop-vac couldn't get.

After a week or so of working as temperatures and daylight have permitted, it runs just fine, seems to get appropriate turbo boost, and (are you sitting down?) there are NO CODES. And no more dash lights. I even put back the door chime, because why not?
The interior is actually in great condition. Upholstery does not show its age.
All the lights work.
Wipers work, and have been replaced.
The AC condenser was cut out, for some reason, and the lower speeds of the fan don't work. Only full-blast blows. I may fix it, I may not. If I need AC, my Passat's works as well as any VW AC ever works. (i.e., when it feels like it.)

I changed the brake fluid, as well. What came out looked like engine oil. Very well-used oil. Surprisingly, the brakes all worked just fine, and there were no leaks. Just a lot of rust.
I also bled the clutch fluid. It was just as nasty.

Now all I have to do is get it registered, and I have a new daily driver!

There's still fine-tuning to do. I want to replace a lot of patched hoses, fix a suspension issue, and replace some missing fog lights etc, but all that can wait.
And next summer, I have another project in getting the red one roadworthy.

 

[pro51492]

Wow that’s some serious rodent damage. Great job resurrecting these old jems. I seen them on CL a few times and was hoping they would go to a good home.

 

[kf6eml]

Wow that’s some serious rodent damage. Great job resurrecting these old jems. I seen them on CL a few times and was hoping they would go to a good home.

Actually, the damage was pretty light. They chewed off several wires, and a couple hoses. And the hood liner was a lost cause. They did chew off the cabin air grille, and make a nest in the blower fan.
But the majority of the problem was just that the engine compartment was packed solid with fluff, nuts, and sticks. And nettle vines had grown up through all of it. Made it a lot of fun to remove.
Surprisingly, the rubber isn't completely rotten. The cooling system still had coolant in it, and it holds pressure. The brakes still work. Even the tires are in good shape!
The fuel hoses in the engine compartment all needed to be replaced.
The interior is in great shape.
I got lucky.