leak on radiator valve thread

[knarf3]

Hi all

I have a problem with a leak on the thread of my new radiator valve. I fitted it yesterday and used PTFE tape but once I did it up It had a leak and when I removed the male thread of the valve it seems as if the thread is cutting the ptfe tape rendering it useless.

This morning I put boss green around the thread and one wrap of PTFE tape but I still had the same problem. The thread seems quite sharp and runs quite deep.

How much tape should I be using? and are there any other tips?

Many thanks

Frank

[covjohn]

i'm not a plumber but we used to use ptfe tape to seal up air pipes on trucks.

to stop it scrunching up and becoming useless as a sealer,you need to have the tail of the tape so it ends facing away from the start of the thread.to picture this you start winding the tape from the top of the thread(or the end of the thread furthest from the start point).when you cut or break the tape the end should be positioned so when you start screwing on the tap it pushes the tape end in the direction of the turn of the tap instead of against the wind,causing the scrunch.also terminate the tape below the level of the thread.

the above description is the reason it has now been superseded by liquid thread sealer in the truck repair world.it takes a bit of paractise to get it right.

another thing to make sure of is that you've got the right threads mating together.you'll never seal imperial/metric threads mixed together.the fact that the thread seems sharp and deep seems to me to be imperial.metric tends to have shallow close threads.