MCP355 constant high pitched sound

[TadZilla]

I've finally got my loop all up and running. However, I have an issue with my MCP355. During leak testing the pump was completely quiet once all the air was gone. Even while some air was still in the loop the pump was quiet until a bubble went into it. Once I put a temp load on the loop, the pump was quiet for few hours, then it started making a high pitched sound (not electrical). Has anyone else experienced this? I've read in a few places that the MCP355 is not supposed to be a quiet pump. I have a D5 Vario, but it does look as nice, even with a new top. But I'm still thinking of switching. Any ideas as to the cause/solution?

Thanks all!

-TadZilla

[BrokenArrow]

Usually it is the vibration that creates the high pitch noise. Did you change anything when you noticed it? Maybe adding the side doors and such after you were finished, etc.

If it is quiet in your hand while running then it is the foundation that is causing the problem.

[TadZilla]

Thanks for the response!

The pump makes the same noise with side panels on or off, and attached to the case or not attached to the case. Doesn't matter, it still makes the noise. I've heard about these pumps becoming off balance. Maybe that is what is going on.

-TadZilla

[BrokenArrow]

Do you have an aftermarket top on the pump? Long ago, I overtightened the four screws and it made a noise from the top rubbing against the impeller.