Periodic Cavitation???...

[bigben2k]

Care to post a link?

[icel0rd]

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-

[RoboTech]

Originally posted by icel0rd
So help me understand this.... The impeller has to be attached securely to the shaft otherwise there is no way it could produce water flow under all the pressure. How can it be somewhat loosely mounted that requires glue to fix?

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...

[MadDogMe]

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 , or they loosen up with use, cause mine felt solid when I looked at it when new, but has started making noises now...