Care to post a link?

http://forums.procooling.com/vbb/sho...rattling+eheim

I found it on the forum. I performed the pump surgery about an hour ago with a lighter and some crazyglue. I crazyglued the neck closest to the magnet that the shaft feeds through that was able to turn most of the way around before the impeller would lock and turn as a whole. I melted the impeller's end to lock with the piece underneath and also applied a little crazy glue to it as an insurance policy.

My pump is totally silent now.


-Ice-

Hey Ice,

Of the four different pumps I use (E-1048, E-1250, ViaAqua 1300 and Danner Supreme2) three of them are designed so the impeller can slip on the motor shaft. The E-1250 is rigidly mounted - no slip. On the other three pumps, the impeller can rotate at least 120 deg. before hitting a hard stop and becoming directly driven by the motor. It's a kinda of a slip-clutch, before a pin or notch engages and hard-couples the impeller to the rotor. I beleive the purpose is to allow the rotor to start turning before having to move any water. I have also heard people say that its purpose is to protect the impeller from damage if the pump ingests a little stone or something, but this doesn't make sense to me as the impeller has to be hard-coupled while pumping and wouldn't allow any slipage in the negative direction.

The impeller/rotor floats axially on the plastic rotor shaft, which in some cases can allow the impeller to rub against one wall or the other of the pump housing. I have experienced this sometimes with my E-1048 at startup but it soon seems to center itself and quiet down.

I hope you get to the bottom of your noisy pump issue... :)

I've seen small aquarium powerheads that are free spinning on the shaft, to act as a clutch. if you pushed it inwards it meshed(the inertia or pressure of the inleted water keeps it meshed?) , but if it cant move the water it slips up'n'over the notch that meshes it...

I think the Eheim1250's do slip but only if you give them abit of gip :D, or they loosen up with use, cause mine felt solid when I looked at it when new, but has started making noises now...