I've also had that happen to me.

Consensus is that LocTite "thread lockers" should not be used (i.e. will not be dependable) in "high heat" applications. Heat being the element added when you want to break a previously bonded thread-locked union free again. Of course we are talking about a higher level of heat, but it's still in that range where suitability becomes "iffy". 

I believe I used a LocTite "gasket maker" series product on my R100 when this happened. When used on threads, these have an excellent sealing capability and a mild thread locking capacity. Try products like LocTite number 510 or 515. (This is also sold at Dodge dealerships as Mopar 4318083.)

Then, when tightening the spigot into the head, use a tool that has positive tightening capability, such as a "strap wrench" or a tool that has positive engagement into the spigot.   

You will really enjoy having this product around. The LocTite "gasket maker" products (unlike the thread lockers) can be applied to oily surfaces. No more wiping both surfaces with strong thinners, carb cleaners, or alcohol. In the case of a drain plug, just wipe off the excess oil with a rag, apply the sealer, and reinstall the plug. These products are also perfect for bolstering gasket sealing, like when you reuse a valve cover gasket. You just smear it on, install the cover, and then wipe off any excess on the outside. It's also an anaerobic (like the thread lockers) which means you can apply it to cylinder base gaskets and NO setup takes place until the part is installed. So you apply it to the cylinder base and if it takes you an hour to install the cylinder, then the gasket maker remains fresh and 100% ready to go to work. Only the absence of air and presence of metal ions activate the sealer. Meaning that excess that squirts out and would normally become unsightly globs of sealer (as with silicone or Permatex gasket maker) simply wipes off. And it's not harmful to the skin, so you can apply it to your finger tips to easily coat both sides of a gasket. 

Hope this helps.

Wobbly, This helps alot.  I'll look this "gasket maker" up on line and try it this winter when i do some carb work.  I thought that the Red Loc-Tite could be used in high heat situations. 

Thanks again.

rick 

Posted by: @red-horse

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I'll look this "gasket maker" up on line and try it this winter when i do some carb work.  I thought that the Red Loc-Tite could be used in high heat situations. 

Just as the "thread locker" LocTite comes n all sorts of application grades and colors (green, blue, red, yellow, etc), so does the "gasket maker". You can go to the LocTite web page and read all about it, then decide which product number might be best for you. 

I'm talking in very "general terms". There may indeed be one specific grade of red LocTite that is not affected by temperature.