Overheating

[dhirocz]

Most car engines can't tolerate thermostat removal either. There has to be a choke plate in it's place to throttle down the speed of the coolant. if not, the coolant doesn't stay in the radiator long enough to remove the heat, and the engine overheats.

I would say you might get away with water for a short time if the cooling system holds pressure. That pressure helps increase the boiling point of the coolant, as does coolant itself. The engine will be VERY prone to overheating under load, unpressurized on water alone. This is a highly unstable cooling system configuration.

With the lower boiling point, bubbles form on the backside of the cylinders far easier and earlier, bubbles which also isolate the backside of the liners from the water, overheating them and further interfering with heat transfer. At this point what happens varies by engine design, but generally, the Pistons and rings get superheated and galled, wrist pins blue from the heat, oil breaks down, the water jackets flood with steam bubbles which collect in the head as the overheating 'runs away', pressure forcing out what water you have left and superheat the engine. Since heat moves up, it usually junks the head/head gasket. What happens is a huge pressurized steam pocket forms in the water jackets. When run under these circumstances, an engine can quickly destroy itself if it gets out of hand.

Havent seen this personally happen on an ISX, but I have seen it happen otherwise and it's never pretty. I wouldn't run mine like that for that reason. Please fix it properly.