Blue (242) or Green (290) Loctite would be OK. Using Red (271) would require heating (400+F) for removal. I use 242 all the time on car motors fasteners, transmissions, and much more. Never had any problems. Usually, you would just coat the threads enough for coverage, but not have it dripping off. If you are careful and use a normal amount, it won't get into the motor. I'm not sure if it would have any impact if it dripped on any of the armatures, brushes, bearings or other components.
Data sheets are on their site:
http://www.loctiteproducts.com/threa...chanical.shtml