How badly am I screwed?

[meby]

I discovered today that the oil fill tube on my Jetta diesel came off and has been spewing oil. It was well over two quarts low. I'm getting a lot of metallic rattles from the engine. It's been making the noise for several weeks now. The motor still runs and hasn't affected power (that I can tell). Am I looking at a top end rebuild or worse?

Edit: the noise sounds kinda like valves.

[oldestof11]

Hydraulic lifters are probably low on oil. Fill it up and see if it still there.

[RumbleFish]

^this. recently bought the wife a car. it had a bad from the top end. The engine in her car had a known issue with the rockers and I planned on getting the upgraded kit. However, after changing the oil and discovering that it was low, the rattle has dissappeared now that it has the correct oil level in it.

[meby]

Oil already done. I think the low oil thing is a coincidence as the low oil light never came on. I had somebody else listen to it and we're thinking its not the motor, but maybe the a/c compressor. I guess its a good thing I bought a vacuum pump and manifold gauges to do the a/c on my truck. I think its pouring right now. (:

[meby]

Found the problem. The stud that holds the clutch on the a/c in place broke. Every time it rotated, it hit the stud making a nasty racket. I don't usually say this after spending $400 bucks to fix it, but thank God it was only the compressor and not the motor.