Hyundai Sonata 2000 150,000 miles
I started getting a noise in the engine that I would describe as "light", and "enginey"
Here is a video with sound.
The sound becomes more frequent as the RPM increases. So it probably has to do with some rotational portion of the engine.
Additionally, I'm not sure if this is relevant, but the airbag light came on a few weeks before this started happening. I think the air escaped probably. Again, not sure if this has anything to do with the engine sound.
an interesting post about hydraulic valves, oil changes, low oil or leak, and dirty oil http://ask.metafilter.com/248194/Can-I-drive-my-car-if-the-engine-has-Hydraulic-Lifter-Ticking
It turned out my engine oil was super low. The dip stick didn't even read anything. I put half a quart of whatever I had left in, and it still didn't read on the dipstick. I can't recall if the engine temperature reading went significantly above that "50%" mark while I was driving it.
Maybe it's tapping because the oil is just low? But why would it get so low suddenly? There must be a leak. Hopefully not a head gasket/plenum leak.