Troubleshooting Your Car's Overheating Problem
Do you have enough coolant and antifreeze in your radiator? To check your levels you will need to remove your radiator cap and peek inside when your car's engine is cool. You could severely burn yourself if you open the cap when the engine is still warm. Checking the level doesn't mean just looking at the plastic overflow bottle. When you look inside the radiator, you should expect to see the fluid level at it's proper level which usually is 1-1/2 to 2 gallons of coolant and water mixed together. If you need to add more fluids and it's more than a pint, you should have the cooling system checked for a leak. Although you may not see fluids under your car, that doesn't mean you don't have a leak so take it to the shop and have them test it.
No leak? Now what? So now that you checked your radiator fluid level and you have determined that there is no leak, you'll need to figure out when the overheating problem occurs.
If the engine starts to overheat while at a stop or when the car is neutral or idle only, it could be an electric cooling fan problem. There is a fan which is located near the radiator that is controlled by sensors to improve airflow across the radiator when you stop or drive at low speeds. This fan regulates the engine temperature to keep your engine cool. If it is not working properly, your car will overheat.
Some cars have two electric fans, one is for the radiator and the other is the air conditioner condenser fan. Normally the radiator fan is closer to the center of the radiator. The radiator fan is responsible for engine cooling, and the condenser fan is responsible for increasing air conditioning efficiency at idle and low speed. Your air conditioning compressor will require the cooling fan to operate at idle as long as the compressor is on. An easy way to check your car's cooling fan operation is to turn on the air conditioner. By turning it on, the cooling fan should come on with the air conditioner compressor.
Some cars do not have an electric cooling fan on the radiator so it will have a belt driven fan blade and fan clutch. This fan should pull a large amount of warm to hot air across the radiator onto the engine. What you want to determine with either fan situation is that there is ample airflow across the radiator at idle. The radiator is the primary heat exchange for the engine, and airflow is crucial.
If your car's engine overheats while at high speeds on the freeway you may have a problem with antifreeze not being able to circulate properly and freely through the radiator. At speeds over 45 MPH, you can assume that your radiator is getting plenty of airflow, so you will need to inspect how your antifreeze is flowing through. The longer and faster you drive, the harder your car has to work so your car's water pump will be pumping large amounts of antifreeze throughout your cooling system. If there is restriction or blockage in your cooling system it will cause your car to overwork itself and it will begin to get hotter and overheat eventually.
Rust and water residue can build up in the radiator and can reduce the flow of coolant at high speeds. Removing the radiator from the vehicle for disassembly and cleaning or radiator replacement are the only two real cures for a clogged radiator. Using a “radiator flush” additive might help as preventive maintenance, but will probably just be a waste of time and money trying to correct a restricted radiator.
Now that we covered the basics to overheating problems, you should be able to take your car to a mechanic save yourself some cash and time in diagnosing the problem.