Is the Locktite thread sealant Teflon type pipe dope? I'm guessing it is. I have used that successfully on wet WP bolts. Also RTV. I think the key is cleaning as antifreeze does not help the seal. After draining coolant, I hit the hole with fresh water. The bolt also. I use a nut or die to clean the bolt and a bolt or tap to clean the hole. When all is clean and rinsed, I dry it. Compressed air first followed by heat from hair dryer or heat gun. When all is clean and dry, dope up the bolt threads and install. I bet that fixes it.