I just got a used Bitmain R4, and while the hashrate's decent, the noise is off the charts (like 65-70 dB instead of the claimed 52 dB). I opened it up and took the fan out, but when I spin it by hand, there's this weird crunching noise that sounds like something's wrong with the bearings. Now I'm stuck on how to get the fan bearing cover off without damaging it. Anyone dealt with fixing these before or have tips to quiet it down?
I resolved this too many times to count with some WD40. Curious what you come up with otherwise.
You can always pick up a new shroud from a non-working unit and swap out the hashboards.
Any grease spray might be work but I think the bearing should be replaced if grease does not work then your last hope is to replace the bearing the only problem it looks like it's hard to remove the metal under that fan motor. It seems that you need a puller to be able to remove the metal part on the motor.
If you have a motorcycle tool you can may be able to pull that metal part the tool looks like this one below