My BroncoII overheats. I removed the thermostat but nothing changed. What is the cause of this problem?

If your vehicle's radiator is overheating and there are no visible leaks, it is possible that the problem could be caused by a faulty thermostat or water pump. These components are responsible for regulating the flow of coolant and water through the radiator and engine, and if they are not functioning properly, it can cause the engine to overheat.
To determine if the thermostat or water pump is causing the overheating issue, you will need to perform some diagnostic tests and checks. Here are a few steps you can follow:

1. Check the thermostat: The thermostat is located in the engine and controls the flow of coolant through the radiator. If the thermostat is stuck in the closed position, it can prevent the coolant from flowing and cause the engine to overheat. You can test the thermostat by removing it from the engine and checking it for proper operation.
2. Check the water pump: The water pump is responsible for circulating the coolant and water through the radiator and engine. If the pump is not functioning properly, it can cause the engine to overheat. You can test the water pump by removing the drive belt and attempting to turn the pump by hand. If the pump is seized or not turning smoothly, it may need to be replaced.
3. Check the coolant level: Make sure that the coolant level in the radiator is at the proper level. If the coolant level is low, it can cause the engine to overheat.

If you are unable to determine the cause of the overheating issue, it is recommended to have the vehicle inspected by a mechanic who can perform a more thorough diagnostic test and identify the root cause of the problem. They will be able to recommend the appropriate repairs to fix the issue and prevent further overheating.

Vehicle make YEAR and model?

You can remove the thermostat and test it for proper operation. But there are many other things that can cause the car to overheat.
Check the coolant level and for leaks around hoses and the general condition of the hoses. Make sure the fan belt is not slipping. Make sure you have nothing blocking air flow through the radiator. When is the last time the radiator was flushed?

check to see if belt is broken, next you will probably have to change the thermostat. if it is not to much trouble you might want to just take out the thermostat and see if that solves the problem

Did you change the thermostat? If not it may be the cause. You can check the thermostat by removing it and immersing it in hot water. If it is working it will open. The thermostat is usually located under the upper radiator hose.

No a heater core alone will not cause a vehicle to overheat. The heater cores sole purpose is to transfer heat generated by the engine to the blower motor so that you can get heat from your car vents. A person could technically remove the heater core from the vehicle and connect the hoses together to bypass it, and the car will run as if nothing happened, minus the lack of heat in the vents.

If the car is overheating, there are three mai issues that could be happening. 1) The radiator is blocked and not allowing coolant to be cooled off before returning to the engine.
2) The water pump is broken. The engine relies on this pump to move the coolant throughout the engine. It may not leak as long as the gasket is alright but the impeller ( small fans on the inside of the water pump ) could not be turning.
3) Lastly and most commonly is a faulty Thermostat. The thermostat is the valve which opens and closes at certain tempuratures and decides if hot coolant stays in the engine or circulates to the radiator to be cooled off. If the thermostat fails, unless you have a failsafe one, will fail in the closed position keeping the hot coolant in the engine and causing it to overheat.

The thermostat is by far the cheapest of the issues so consider changing that first along with a coolant flush before considering putting a new rad or waterpump. You can usually get a thermostat, 2 jugs of coolant and a flush kit for about 50$ at pretty much any parts store. Becareful however not to drive a overheating vehicle as gasket burning and head warpage can occur, which will require rebuilding th head.

Good Luck

Thermostat may be installed upside down...this can cause overheat.
To test your engine...if you don't think thermostat is faulty, remove the thermostat.
This is sometimes called "running cold"...and it should not overheat. If it does, you have bigger problem than thermostat.
You can test thermostat too by placing it in hot water thats not quite boiling and see if its opening properly.

Hope this helps...

it appears that you have a large air pocket/low on coolant. The engine is getting hot due to the lack of coolant but there is no heat because nothing is flowing through the core.

follow the hose that comes from the top of the radiator to the motor, disconnect the hose and the housing,then the thermostat

Are you putting the thermostat in correctly? It it will not work backwards.

And to confirm that there isn't a different problem, take the thermostat out all together and see if it overheats.

Engine not fully warming up is not usually caused by the thermostat. Stats usually fail closed, not open.

You will want to check the water temperature sending unit or gauge after verify the water temperature with an external calibrated thermometer. You can attach and insulate the external thermometer to the housing where thermostat is located.


Reply back what you figure out. I will be happy to help you further.