Dang! I've been thinking about this "loan to a neighbor" thing, and it just doesn't work.
Loaned my Volvo sport sedan with a finely-balanced engine to a friend who was in his rookie year SCCA, and told him "no screwing around!" -- he just wanted to ferry somebody to a park entrance to get entrance tickets. He came back in a different car. He innocently described it this way: "The guy was just commenting on how smooth the engine sounded, at around 6 [thousand rpm] grand. Going into a left turn, I said, 'watch this!', and downshifted [that's now 8 grand]. When we came out of the corner, it was making lots of noise." He had spun the crank bearing on #4.
Loaned money to a couple of friends, and said "we'll not talk about this again. Pay it back when you can". Never heard from either one again. Well, at least we didn't talk about MONEY, right?
Folks use seldom-run gas equipment, and don't turn off the gas feed and empty the carburetor reservoir before storing it, guaranteeing a carb cleaning the next time I get it out
And tools STILL keep disappearing from my barn....
(sigh) So it goes. Now I just offer to do it FOR them. I could be upset, but then I think about all the things God has forgiven ME for, and bow my head in gratitude.
I hope you get your engine fixed. May God grant you insight and guide your hands!