Urgent consultation for connoisseurs

Hello friends ... I have a doubt that I have very worried ... I have bought a Merdes Benz 190d of four cylinders automatic box ... and the other day when I have the open capo and want P to other marches if ... if they know that it can cause this, it would help me know it since I do not know if it is something serious or not ... thank you very much!

Do you also throw water if you accelerate with the lever in N? Is it by increasing RPM? Does water consume you? It is that I do not see any relationship with the water circuit ... more than when starting. Do you lose with the plug placed?