Tunze Silence, Rust in Propeller Shaft?

[atp0726]

I have a Tunze Silence 1073 and while cleaning it today noticed a rust like substance in the drive shaft. Scraped it out and almost looks like there is a hairline crack in the shaft.

I am running the pump in a bucket to see if the rust colored substance forms again and have no plans to put it back in the tank.

Is this an issue anyone else has experienced?

 

[rvitko]

Which model silence pump? Do you have a photo?

 

[atp0726]

Silence 1073.020

I pulled all my pumps to check for corrosion. The impeller chamber had some scratches and a rust colored substance. When I cleaned it away it almost looks like there is a tiny hairline crack. Due to the location and size it’s very difficult to see.

I am running it in a bucket to try and duplicate the issue.

 

[rvitko]

I don't see anything. The motor inside is magnetic, so it is common that any iron dust, including GFO will be attracted and stain, that plastic wall is quite thick, behind the plastic mold which is about 1mm thick is a couple mm of polyurethane potting before any metal. My suspicion is it simply has a scratch and iron particles attracted to the magnetic field stained the scratch. Removing the cooling duct would let you see it better possibly.

 

[rvitko]

In general if water has reached the core, they won't work as the coil corrodes and the contact is broken and typically the safety for overheating would activate before that and shut it off.

 

[atp0726]

I have never used GFO, so now I am wondering what the source is of this potential metal dust that i removed.

What part and where is the cooling duct?

 

[rvitko]

The grey piece on the right side can be pried out and removed. Their are many sources of iron particles in households and in aquariums, sharpening knives, driving in screws and nails, using steel wool, using razor blades, many substrates have some level of contamination even. I also see new products that have some iron filings on magnets from the machining processes. Iron rust is generally harmless, GFO is exactly that Ferric oxide, rust.

 

[atp0726]

Mine is all black and just like the one pictured. I didnt see an area where a panel was removable? I would like to at least open it up and make sure there was no water intrusion before using it again.

 

[rvitko]

As a general rule, if their was water intrusion, it will trip a GFI and it will not run as the corrosion would break the coil continuity and their would be stray voltage present at the full mains voltage. I would be 99.9% sure this is only a minor cosmetic issue of a scratch that some iron deposited in.

 

[Rdf79]

Was there a problem with the earlier releases of the 1073.05?
I have three of them and was pretty disappointed to find that all the drive units had rusted internally. None of my other pumps have this problem even though they're older.

 

[rvitko]

This issue will only happen with pumps that have rare earth magnet impellers, ferrite impellers are the norm and cannot degrade this way as ferrite cannot rust, rare earth magnet impellers save energy by using a weaker motor with a stronger permanent magnet, but the magnet must be encapsulated in plastic and if the plastic is ever breached, the magnets will rust and fail. There is no specific defect or batch issue, but about 4 years ago the impellers were updated to use a thicker and stronger plastic shell. What typically would happen is the plastic would be scored by a snail or sand/gravel and then water would reach the magnet, this is still possible, but less likely with the new plastic which is grey in color.