Charge Cooler Pump Operation B8 S4

Can anyone tell me if there should be evidence of coolant circulation - ie coolant passing out of the small return pipe into the coolant reservoir, when the pump is activated using VCDS and the engine is cold? I have been checking this prior to replacing the coolant so that I know if/when that pump has been primed, so far, before touching anything, I can hear the charge cooler pump running and a "hollow" pumping noise coming from the opened top of the reservoir, but no coolant is being pumped out of the pipe into the reservoir.

I have repeated this "output" test on my wife's 2015 VW Polo, but on that one there are fewer options to switch, the one I tested/switched was "coolant pump" - its electric coolant pump, like the one of the 2011 B8 S4, did switch on and it did pump coolant into the coolant reservoir via the small return pipe - but that car's engine was still hot/warm.

So my question is, for anyone that is in the know about these things, should that charge cooler pump on my S4 circulate coolant into the coolant reservoir when it is running and the engine is cold, or even although I can hear a "hollow pumping noise" but no coolant being pumped into that reservoir, is my charge cooler pump u/s although its motor seems to be running, ie impellor disconnected/broken?

Thanks in advance.

Bump Bump!

No knowledgeable B8 S4 owners out there?

No, it is charge cooler pump I am meaning, my car is a 2011 B8 S4, and the option for coolant pump does nothing in VCDS - which was obvious when I then looked further down the output tests list and found charge cooler pump. My car has a mechanical coolant pump but I initially expected that the "coolant pump" option was actually referring to the charge cooler pump as that is the only electric coolant pump on that car.

Thanks for trying to help though!

I really do need to put some effort in and take a look at the cooling system schematics to try to work out if this electric pump should be returning fluid into the coolant reservoir or not.

My old 2000 VW Passat 4Motion had a "run on" electric pump, and after stopping that car when hot, you could see the coolant being pumped by the coolant returning into the coolant reservoir, similarly, my wife's 2015 VW Polo 1.2TSI which has maybe 3 coolant circuits, has a mechanical coolant pump and an electric pump, the electric coolant pump is used as a "run on" pump after stopping with a hot engine, and I can see the coolant being returned to the coolant reservoir while that pump is running.
But, I know that I'm not comparing apples with apples, this electric charge cooler pump in the 3.0TFSI seems to be only for doing that job, so maybe it is just pumping coolant round a loop like the mechanical coolant does, and so will never end up pumping coolant round via the coolant reservoir small pipe. I just wish that I had worked this out when the car was a lot newer and so I would not now need to ask this question.

So, finally, one question or favour to ask B8 S4 owners, when you stop your car after a longish run, ie long enough to warm up the coolant system properly - if you look under the bonnet, while this charge cooler pump is still running after the engine has been switched off, can you see a flow of coolant being returned to the coolant reservoir via the small pipe that enters the reservoir at the top?

I think that I have answered my question, there is a one way valve built into the only link this section has with the small return pipe to the coolant reservoir.