Willys I see what you're saying but you are acting as if the thermostat is "isolated" from the hot engine water. That is not the case. It is sitting in the engine water so once the water is above the opening temp, it should open. Even if the water just above the stat is cooler. That would throw it off by a few degrees (delay the opening) but should not make the gauge peg before it opens. Could be a combination of things here. Very slow acting thermostat and a plugged bypass. This would make sense. Drilling the holes only cost him a few minutes of his time and it is worth a shot. If it works great, if not the real problem needs to be fixed. They didn't come from the factory with holes drilled in them and they worked.