Is a MAK 4 supposed to be loud?

[Quinster]

we got his at a local supplier...if you can remove them and leave the pump off for the time it would take to get them (or if you have a back up pump you can run in the mean time), all they did was measure the ID and OD and had a replacement in stock. We were told they were a common size. Sorry I can't help more with where to get them...maybe someone local knows of a bearing company.