Leaking radiator

[Vicky2612]

We are moving house in 3 weeks and our radiator has started to leak from the bleed valve.
We don't want to pay for a plumber as the new owner is doing that when she moves in.
We just need a cheap temporary fix so water is not leaking on our floor.
Cold weather means we can't simply turn the radiator off.
Water seems to be dripping from the washer rather than nut.
Any advice welcome!

There is an image of the valve on my profile

 

[newbuildinstaller]

-buy another air vent plug,
-Turn off both rad valves
-Open air vent till water stops (will be very little maybe none)
-Remove old vent with a spanner
-Replace with new
-Open valves again bleed rad of air
-top up system if a combi

OR just try tightening it

http://www.screwfix.com/p/radiator-vent-blanking-plug-chrome-bsp/40972