My radiotor gets cold after 10 minutes

[Margie]

One of my radiators which is the biggest one in the living room gets hot at first and I can hear the water flow but after 10 minutes the water flow stops and the radiator gets cold. It has the trv valve and I have to put it close to 4 in order for the water flow to start. The retun valve is open all the way

 

[ShaunCorbs]

Try removing the trv head