Same with my granddad, he had to work in the Opel factories. Their gig was to make cars that would function when tested, but that would fail within a couple of days of delivery to the field.
So, whenever they could they would structurally weaken some element deep in the engine just enough to make it fail.
This is a lot more difficult than it sounds, it is a study in planned obsolescence, because if you make it fail to soon you get a bullet to the back there is not a lot of room for error.
Finally they settled on making a fairly small cut in the wall of a piston, apparently that was good enough to survive a test or two but would fail quickly enough under actual use.
So, whenever they could they would structurally weaken some element deep in the engine just enough to make it fail.
This is a lot more difficult than it sounds, it is a study in planned obsolescence, because if you make it fail to soon you get a bullet to the back there is not a lot of room for error.
Finally they settled on making a fairly small cut in the wall of a piston, apparently that was good enough to survive a test or two but would fail quickly enough under actual use.