slk 250 diesel water pump

[robbo21]

I have just replaced my water pump on a 2013 SLK 250 d and all seems ok. But I have noticed a pump running sound keeps going after I have stopped the engine. It seems to be coming from a round topped component next to the header tank. Could some one tell me what this item is . It appears to be plumbed int the cooling system . Thought it might be the thermostat . Is it normal to keep running after the engine is turned off for a couple of minutes. I never noticed it before changing the pump. Thanks for any info.

 

[alexanderfoti]

This is the aux pump and it will have always done this.

 

[robbo21]

Thanks alexanderfoti for the info. All good.