Diagnosis
That's the sound of the pump struggling because it's clogged with mineral scale. It's the most common cause of loud noises in these single-serve machines.
How to Fix It
You need to descale, and I mean a proper descale, not just a water run. Get official Keurig descaling solution or a white vinegar/water mix (half and half). Fill the reservoir with the solution. Without a pod in the holder, run the largest brew size (12oz) into a mug. Discard that mug. Keep running brew cycles until the 'add water' light comes on. Then, refill the reservoir with fresh water and run at least 4-5 full reservoirs of plain water through to rinse it all out.
If That Didn't Work
The noise might be coming from the needle that pierces the pod. Lift the handle and look at the top needle inside the pod holder. If you see old coffee grounds or a piece of foil pod stuck on it, use a straightened paperclip to gently clear the gunk. Don't scrub, just poke the clog loose.
Heads Up
That grinding noise is a warning. If you ignore it and keep brewing, you will burn out the pump motor, and that's basically the end of the machine.