My father always wanted to strip and rebuild an engine with me, but I wasn't too interested. The nearest he got was a set of books from the 1930s describing how to build a car from scratch. The first part was how to build the tools necessary to build a car, e.g. how to drill holes to make a cylinder block.
The nearest I got was designing and making a computer in 1976, using the primitive construction techniques I developed three years earlier, as described in https://entertaininghacks.wordpress.com/2015/02/21/a-40-year-old-hack-disinterred/ That hack still works.
My grandfather was the "father figure" when it came to things mechanical... I remember crawling through the guts of a combine from the back forward, to put vise-grips on a stripped carriage bolt in the chaff separator chute; one of the few times we weren't at odds and I could tell he was proud of my mechanical aptitude. "You did good, boy" was probably the closest to actual praise he was able to muster; I knew this about him by then and took it as it was given, holding it close in my heart, feeding and cherishing the glow as only a 10-year-old boy can.
Another time I overheard him talking about me tearing down the crankcase/transmission of a beat-to-death RT1-360 dirt bike I'd scrounged... I had every last bearing and gear cluster and spring and ball laid out in rows on the bed of an old hay wagon. I worked on that thing for three days, transferring every part from the grenaded crankcase halves to a new set I'd bought from the local Yamaha dealer.
He never admitted it to me, but I overheard him there talking to his grown-up friends, and he was amazed at me doing all that intricate shifter mechanisms and rebuilding the clutch pack and new crankshaft seals, and actually reading and understanding service manuals an inch and a half thick. I was 12 years old at the time.
It was one of the few things we sortof shared before he died; and now a bittersweet memory because I never did tell him I overheard. I so wish I had; it would have been common ground for actual reconciliation rather than the uneasy, grudging "understanding" we arrived at instead. *sigh*
*mnemories*