Ever since I fired this new motor up with the w2 econo heads I've been having issues with the passenger rear header bolt leaking coolant. At first, it was trickling out a little bit when I used ARP thread sealant. I put it back in using copper RTV instead and I had no more wetness/dripping on the outside, but I was still getting occasional little puffs of white smoke out from around that primary almost as if it was leaking inside of primary. I pulled the header gasket out and it looks like it was wet all around the bolt and possibly caused the gasket to leak where the antifreeze softened it (which would explain the smoke trails).

Not really sure what to use at this point, anything thicker/more durable than RTV? Never had this issue before, and even the front header bolt which is also a wet hole never has any issues with just using the Arp sealant.. No cracks I can see around the port or bolt area, just seems like it's pushing out the threads. Could excessive pressure in the coolant system cause this? Compression test showed all cylinders within 5 psi of eachother but haven't done a leakdown yet.

Thanks!