I just completed my custom loop with the XD3 as the pump/reservoir and have been in the process of doing a leak test with fluid and with the pump running (already checked air leaks). Currently, only the pump is hooked up via molex to power with PWM disconnected.
What I am seeing though makes me wonder if there is something wrong with this pump. There is a large constant rattle that almost sounds like a metal scraping that is present. At first I thought that it might be an air bubble in the pump, but after running all night, the sound remains unchanged. It has persisted even after tilting the case. When the PWM cable is connected, in theory the pump should run at 60% and it would possibly not be as loud, but on the contrary, it is the same, if not louder. In fact, the only time that the sound is not present is a brief half second when starting to tilt the case backwards, but it quickly returns no matter the case orientation. The sound is definitely coming from the pump and do not see anywhere that the pump is vibrating against anything.
I do not believe there is air trapped in the pump as I would have expected it to be purged by now from running overnight. The only other possible explanation not involving mechanical/structural fault in the pump/res combo may be some back pressure from the T junction to a drain valve shortly after the outlet from the pump; normal flow with the drain valve closed is to take a right angle turn into the GPU block. But to test this theory I would need to drain the loop and reorient things to which I might just change courses anyways and switch to a D5 pump (the XD5 might fit but there is one location it could fit and it is questionable if there is space, otherwise would probably be looking at another brand).
https://imgur.com/a/mIBICXm
Thoughts?
