I think it should not explode when the unit reaches a certain amount of health maybe it could be immobilized and unable to rotate though, for example imagine a WW2 mod and you have a tiger tank, its attacked by shermans who attack the hull, on reaching some point of health the turret can no longer rotate because of lack of power or whatever(it was manually operated so probably not that, more likely jammed by splinters), so you can withdraw the tank but not move the turret until the tank itself repaired. It would also give and enemy player two choices, wreck the turret and stop his attacks but he might get away or be repaired or reinforced, or attack the hull and possibly destroy him along with the turret but he will constantly fight back, giving you lots of damage.