Hi guys,
Noise can only happen if there is a bad bearing, (all our bearings are NEW), if there is NO lubrication (assuming the correct type and amount of fluid was used) or air in the system. Almost all the issues we deal with on noisy pumps have to deal with air being trapped in the system or being created internally by a restriction.

Bleeding the system is absolutely necessary. Check out this 2min video we recently put together on the process. http://youtu.be/ts6vX8csaTA