hot indicater light comes on when resevior is low

there is a block temperature sender...when the coolant gets low, there is not sufficient coolant flow to cool the motor properly...needle goes to H~

Has this one had a panic overheat and refill with hose water....then never flushed with 50/50...then corrosion invades the block chokin' the coolant passages? This can happen and requires extraordinary measures to correct~

if coolant is low, the hot indicator flashes even if the car is not really hot. this is normal letting you know the coolant is low. you need to check for a leak if the coolant is getting low frequently.

If there is no thermostat, the water flows rapidly without any restrictions (hopefully). The radiator does not have enough time to cool the antifreeze/water down and the engine will over hear, especially if you are low on fluid. If the fluid is constantly being lost, find the leak, be it a hose, connection or worse yet, head gasket. First check the oil in the engine. If it is a milky color, you have a major leak in the head somewhere. If the oil is normal color, check under the car and see if there is a leak of the radiator fluid. Check all the hoses for dampness and the connectors. Do this after the motor is cooled down some or you may get burnt. Use antifreeze to fill the reservoir unless you are expecting to replace it after fixing the problem.

If the engine is hot, stop, lift the hood and see if the fans are working. Any restrictions like excessive bugs, cats or birds on the radiator blocking air flow? It really is a simple fix if you use a process of elimination to find the reason for the over heating. Put a thermostat in if you don't find any obvious leaks and see if that helps. When you over heat, it may push the liquid out causing the level to drop also.