Не понимаю auto.

[Barn]

Речь идет о блоке цилиндров.
It is usual to refer to cylinder wear as the difference between the original size of the new or reconditioned bore, and the maximum size recorded in any position by the bore gauge.
If in doubt concerning the original size, clean off the carbon at the very top of the bore; this part of the bore should be unworn—the very bottom of the bore is unreliable, being prone to distortion when the cylinder walls are unsupported and project into the crank case.
Непонятно последнее предложение:when the cylinder walls are unsupported and project into the crank case- как стенки цилинедра могут быть врезаны в картер??? Объясните, пожалуйста, что я не так понял.
Заранее спасибо.

[tumanov]

втулка цилиндра может выдаваться в картер.