I was getting a low coolant level warning so took expansion bottle off and cleaned it out to free up the sensor but it didn't make any difference so I bought another expansion tank of fleabay, seller had sold over 500 of them so I thought should be ok for £26. Fitted it and noticed the black screw in bung which I had to use of my old bottle was a little loose when screwing it in and now I have coolant getting up past the thread and leaking.

Now being threaded it cant be some sort of release valve so wondered if it was there because the bottle is used on another vehicle that requires that threaded hole.

Anyone know what its for as im thinking of just wrapping PTFE tape around the thread

Cheers

M9G 2008 RRS 2.7TD in Stornoway grey, black leather and 22 inch alloys
Xtrons Android head unit

Ok think ive sorted it, ive screwed it in as tight as I can get it and it has stopped, I think the top of the threaded hole has a slightly different taper to that of the black bung so had to screw it in really tight for the black bung to seal around the top of the threaded hole. 2008 RRS 2.7TD in Stornoway grey, black leather and 22 inch alloys
Xtrons Android head unit

Yeah I think the black bleed screw is different.

If the black thing was shown in the ebay pic, contact the seller and ask for a black plug. (contact them anyway)

My cheap ebay one came with one

thanks Andy, cant see one in pc so will contact them.

Cheers  2008 RRS 2.7TD in Stornoway grey, black leather and 22 inch alloys
Xtrons Android head unit