It keeps running hot and the thermostat is is no longer in the car what should I do

Have the radiator cleaned, back flush engine and heater core, make sure fan(s) is running, make sure water pump is pumping, I have seen pumps with rusted off impellers.

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Originally Posted by Galvinthoms

Install a lower temperature thermostat It will help you engine run cooler and prevent it from overheating.

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They said "It keeps running hot and the thermostat is no longer in the car"

You likely need to install a new radiator. Corrosion or phosphate scale are causing passages to be blocked. Afterwards, refill with a 50/50 mixture of DexCool and distilled water; otherwise, buy prediluted DexCool.