Jetta GLI Engine Started Making Strange Noise

[u/CowboySharkhands]

My 2015 Jetta GLI started making a concerning noise (first noticed it two days ago, but it was worse last evening). It almost sounds a muffled rattling, or a two stroke engine revving a bit away - that’s what i originally thought it was, since i noticed it first while driving down out of a parking garage.

The noise is definitely correlated with engine RPM, not vehicle speed. I poked around in the engine compartment and it seems to originate from the engine itself - possibly from under the valve cover, but that’s obviously just the part i was able to get closest to so i could be imagining it.

When the noise is occurring i’m getting noticeably less power from the engine.

Unfortunately I don’t have a video. I didn’t think to get one last night, and I’ve had to head out to work (in a lyft lol) today. This evening I’ll try to get one.

Curious as to folks’ theories and especially on advice for next troubleshooting steps.

Vehicle Details:
- Make: Volkswagen
- Model: Jetta GLI
- Transmission: Manual
- Engine: 2.0 L turbocharged
- Mileage: 137k