I've got issues with my Corsair AIO H110 that I bought back in 2015 as well. The pump is giving very loud grinding noise, cpu temp is still ok at 39C range.
Googled a couple of potential solution like tilt the case by 45 deg in every directions and take out the radiator and give it some shaking but to no avail.
The time when the noise stopped was when the pump is not working. temp shoot up to 60C.
Still thinking of replacing the AIO with air cooling since my rig is reaching the end of life already.
Failed AIO pump before