If the engine is grinding get a new engine, it's junk, sounds like improper break in procedure possibly or too low of oil content. If you want to be sure it is or is not junk, take the cooling head off and look inside at the sleeve and piston, if that looks good, take the engine out of the truck and pull the back plate and look indside the block to see what's going on. Sounds like it's trashed though. Good luck. Oh by the way if the engine is junk Himoto has a life time warrenty on there engines, just send the engine in with half the cost of a new engine and there warrenty form filled out.