P38A Lower radiator bolt problem

I am trying to remove the radiator on my D2.5. Problem I have is that the N/S lower bolt has freed from its retainer so that the bolt and nut rotate when trying to undo the bolt. Given that its a little tight for space seeing that the oil cooler is next to it, how can I get the head of this bolt off so I can get the the rad out?

Drill the nut ,its brass n soft ,jam the blade of a screw driver sideways half in the hole and turn the bolt slowly.,,worked for me.

Thanks dubbleRR. Worked a treat. Drill it and that freed the thread, had the bolt out in 5 mins. Found that you cannot squeeze the rad past the fan.

No wondewr RAVE tells you to remove the fan!