If it's any help, I did a detergent backflush on my machine a few months, when the kitchen extractor hood was on at the same time. I engaged the pump, but I couldn't hear it over the extractor.

I then, of course, got distracted and wandered off. Came back 40 minutes later and it was still running, but sounded rough. Touched the motor - hot. Touched the pump - OW! Very hot! Removed the PF and ran some cold water through for a few seconds to cool the pump.

Tried it again later and it sounded fine, no strange noises or funny smells.

Still working perfectly several months later. There may be latent damage to the pump, but I can't tell.

darrensandford wrote:I engaged the pump, but I couldn't hear it over the extractor.
40 minutes later and it was still running, but sounded rough. Touched the motor - hot. Touched the pump - OW! Very hot! Removed the PF and ran some cold water through for a few seconds to cool the pump.
Tried it again later and it sounded fine, no strange noises or funny smells.
Still working perfectly several months later. There may be latent damage to the pump, but I can't tell.

[a doubt about your comment comes to me.. do you mean "I engaged the pump without water"??]

Same thing happened to me, same thoughts comes to me... no strange smells, sound rough (and metallic, and like it tried to, I'd add), and hot, ... I suppose to so like yours one... I can touch with hand easily... maybe was at 40 °C (but the aluminium casing, impossible to know nothing about the interior.), and bad feelings about the future of the machine because of this
So you mean 40 minutes with no water and now still perfectly works like first day without any bar noise / sign? (If I understand well), that proves the durability of this motors... although, as Dan says, "is definitely not recommended" use them like that.

cannonfodder wrote:I would be more worried about an empty boiler and energised heater for 4 minutes. That has a bad tendency to blow out heating elements. If you hook everything back up and it works without issue, count yourself lucky and make some coffee. The good thing about these parts (or bad thing) is that there is very little to go wrong. It will work, or it will not.

Well.. I have test the machine and, apparently works normal.. I consider myself lucky... Ufff
Anyway.. I though on this before... and there is not reason to be worry, because while the boiler is refilling, the heating element is off... Thankfully, I was lucky on one thing...and the decision of the engineers to switch off the heating elements while the boiler is refilling, help me to not ending of broken the machine...
Thankfully.....

You left it to back flush for 40 minutes? What is the point of 40 minutes of back flushing?

burgosma wrote:do you mean "I engaged the pump without water"??

No, there was water in the system, just that the pump was running for 40 minutes with the backflush disk in place, so the water couldn't go anywhere, which meant the pump wasn't being cooled and the motor was under load the whole time. At least it was lubricated by the water in my case, although the brass pump housing was painfully hot to touch, so it must have been at least 60 C. The aluminium casing of the motor was also hot, but not painfully so.

napierzaza wrote:You left it to back flush for 40 minutes? What is the point of 40 minutes of back flushing?

Read my post again, please. I didn't intend to leave it for 40 minutes, I actually intended to run the pump for 10 seconds or so.

darrensandford wrote:just that the pump was running for 40 minutes with the backflush disk in place, so the water couldn't go anywhere, which meant the pump wasn't being cooled and the motor was under load the whole time

all right... thanks for the clarifications (I didn't understand you well, sorry).
so the problem, at least, was similar as mine one... well... the conclusions are similar I think... the pumps are heavier than the people usually thinks. I don't know if I am correct... but is my first conclusion.... (of course is still a terrible and horrible happening, but... it seems at first that without heavy consequences... so far today... (I cross my fingers for if the flyes))

burgosma wrote:the pumps are heavier than the people usually thinks. I don't know if I am correct... but is my first conclusion....

From Fluid-o-tech website, may not be the exact model used in our machines, but it is build the same way

The vanes are part #9. They are made of graphite. Normally, they run in water, providing lubrication between the vanes and the inner walls of the pump. When you run it with only some water left in, friction happens, creating heat and wearing the vanes. If the pump goes completely dry, the heat rockets until the pump fails.

As such, it is possible that running the pump with almost no water for a few minutes results in premature wear. Hence, it may not lead to immediate damage but may result in a reduced life expectancy. Time will tell...