6105 drive unit rusted

[dzhuo]

Hi Roger,
I have 2 Tunze 6105 and I notice there are rust in the drive unit when I was cleaning it yesterday. Unfortunately, I forget to take a picture but the rust is in the tip of the drive unit (red circle):

Both 6105 have been in service less than 6 months. Is this normal? Do I need to replace them?

 

[rvitko]

It is not impossible but the drive unit you show should have a titanium shaft, in July of 2010 we changed to titanium grade 2, prior to that we used an alloy 316TI which is stainless steel with some added titanium, it is what high end brake and fuel lines are made of. Actually we will change again in just a few more months to surgical grade titanium because it is stiffer and less likely to bend. It is possible that the shaft is the older alloy which would get some corrosion in the areas it is covered (under the bushings) , but generally the silence disk on the bottom indicates it was made after August 2010. The corrosion will do no harm, it just is not attractive, in terms of harm to the tank, people add rust to there tanks every day (GFO phosphate remover). It is also possible that this is just a stain, if the shaft feels very light and almost like aluminum and somewhat dull it would be the titanium grade 2. If it is heavier and a bit shiny it would be the 316ti.

 

[dzhuo]

Hi Roger,
The picture I show is just a photo I stole from your web site. The one I have is black. Does it make a difference? Is it the newer or the older generation? If the corrosion doesn't do much harm, then I won't worry about it too much. Just want to make sure it doesn't continue to corrode to a point where it will affect performance or break.

 

[rvitko]

It won't break but it will get pitted and continue to corrode where it is covered but it will last for a long time. I would wait for the Titanium Grade 5 shafts (surgical) the Titanium grade 2 cannot rust but seems to have a problem with bending and noise from bowed shafts. The new Grade 5 versions should be out in May.

 

[dzhuo]

OK. I won't worry about it for now then. I will wait until the surgical shafts come out and then maybe I can replace it. As long as the material isn't harmful, I won't worry about it.

Any idea of how much to replace the drive unit with the surgical shaft?

 

[fishview]

I am wondering what's the advantage of Titanium Grade 5 shafts (surgical) over ceramic shafts.

 

[rvitko]

Ceramic is easily broken and generally a pain in the butt.