Hey gang,
I also got in the 18mm tap and die set I from Amazon. It's cheap, but it did work!
I used the die on the 18mm crank bolt and I think it came out pretty well. Once back at the car I'll use the tap on the crank snout to try and clean it out.
It was successful in removing that very stubborn putty or sealant that was in the threads. That's all for now. We're in a heat wave here in Maryland, so I'm hunkering down in the house this weekend until the heat breaks on Sunday.
Cheers!