With the greatest respect, I think it's commendable that pilots are keen on learning about their aircraft but your garage wouldn't have you on the shop floor whilst they were servicing your car so why expect the same from your aircraft maintenance company? The hangar is their property as much as the aircraft is yours. Who pays if you knock a magneto timer onto the floor or stand on compression test gauges...
Engineers want to get on with their job without people getting in the way and don't forget that if you slow them down to explain things, you'll end up paying for the time.
There's also the issue of employer's liability. Plenty of hazards in a hangar.
Explaining aircraft issues to an owner for a few minutes is normal in just about every hangar but in most companies I think it's unlikely that you'd be allowed much more.
Imagine if an engineering passenger kept looking over your shoulder whilst you were flying.
