pork loin without a meat thermometer??

You can stick the tip of a knife or metal skewer into the centre, and then hold the tip of metal against your wrist - that will give you an indication of how hot the internal temp is. If you're comfortable squeezing the meat to sense how far along it is, that is another way. When you think it's close, cutting into it in an inconspicuous place is the best way to be sure.