Glow plug leak

I had an issue with the 200tdi I hvae rebult where a glowplug I had to drill out on reassmbly had a blowby issue:



Having done a little research this appears to be a fairly common issue with diesel running ali heads and you can get re-thread kits for glowplugs so I ordered a thread repair kit despite it not receiving good review from Britannica restorations. (link)

I have successfully rethreaded the glowplug using a timesert. I also glued the timesert in place with high temperature epoxy just to make sure as using the glow plug re-thread kit was just as difficult and awkward as the Britannica restorations makes it out to be! Having removed the head for repair and now refitted and had running there is still a slight leak but it greatly improved. What seals the glowplug in the head, What part of the glowplug forms the seal. Is it the the threads or is there a seat somewhere that should seal? The old one was very black and sooty which the others were not so not sure if something else is worn and preventing the correct seal.

The glow plugs are sealed purely by the thread I thought and they aren’t tight either. You sure you haven’t over sized the hole.

I had a glow plus strip pretty much all the thread out when I took it out. Just enough thread left for the new one and it’s not leaked past.

Don’t think it take much to seal

Just looking and it looks to me like the bottom of the plug body just under the threads is a tapered seat? so I would be trying some thread sealant on the threads, green loctite type of thing.