pump not starting sometimes

[ebprod]

For the last couple of weeks, my VII pump will sometime not start. It starts on the pre-infusion, then nothing. The next time I try it, it works fine.

It has been doing this about every other day, ever since I used citric acid to descale the machine. Did I do something to damage it? Is there some maintenance I can do on it?

I took the pump apart a couple of years ago and it looked clean at the time. I've owned the machine about 4 1/2 years.

thanks

-Joe

[Endo]

Time to take the pump apart again and have a look.

Check for the classic shaft rust issue and at the bearings. Do a test of the motor alone to make sure it is actually the pump.

The descale solution is pretty aggressive stuff. It took the plating off some of my parts. It likely degreased something on your pump enough to cause it to stick.

[ebprod]

I took the pump apart, and this is what I found. There is a small spot of rust on the shaft. There is a powdery black substance, I don't know what it is- it is a bit greasy.

What is the next step?

-Joe

[Endo]

Looks pretty good.

How does the pump feel when turned by hand? Any binding?

How about the motor? Does it start and stop OK?

[ebprod]

The motor runs freely.

I can turn the pump by hand smoothly. I don't know how much resistance there should be. I left the water hooked up, and I would say there was light-medium resistance.

can the pump be lubricated?

-Joe

Looks pretty good.

How does the pump feel when turned by hand? Any binding?

How about the motor? Does it start and stop OK?

[Endo]

The motor runs freely.

I can turn the pump by hand smoothly. I don't know how much resistance there should be. I left the water hooked up, and I would say there was light-medium resistance.

can the pump be lubricated?

I wouldn't try taking the pump apart. As I understand it, there are lots of little spring-loaded bits that would make re-assembly almost impossible as you see in this diagram:

Procon Pump

procon.JPG (69.92 KiB) Viewed 7334 times

Also, if I'm not mistaken, there is no internal lubrication on these pumps (except for the bearings). I think the vanes are made of graphite.

Since it seems to turn freely, I can't say much more. Perhaps someone else might have some ideas (I'm a Mini owner so I only have experience with vibe pumps). Perhaps you can get some clues by reading some more about vane pumps here:

http://en.wikipedia.org/wiki/Rotary_vane_pump

[ebprod]

I cleaned out the black powder and up it back together. So far it seems to be working fine. I guess I'll just have to wait and see if it happens again

-Joe