If you’ve ever sat in a rush hour traffic gridlock pattern, watching the temperature needle on your car, truck, or SUV dashboard, inching swiftly upward, you know how scary it can seem. A hot engine, after all, isn’t just a temporary inconvenience; serious damage can result. Your smartest way to prevent engine overheating is to perform regular checks and maintenance on your automotive heating and cooling system.
Your vehicle owner manual almost certainly shows you the layout of the heating and cooling system. This system usually includes:
– a radiator located at the front of the vehicle, usually positioned directly behind the grill
– a pressurized radiator cap that sits atop the radiator; this must always be removed slowly and with great care with the engine is hot
– radiator hoses – most vehicles have at least two: an upper and a lower hose
– a coolant overflow tank which is where you usually add a mixture of both water and antifreeze
– the crucial water-coolant mix itself which usually acts to protect your vehicle against any extremes of temperature
– a valve or petcock below the radiator you can release to empty or flush the coolant system
– a thermostat which, as its name implies, is a device which tries to regulate the temperature of the engine; over time, the thermostat can stick open/closed or wear and die
– a water pump that helps circulate water through the system to cool
If you have air conditioning installed, you also have an air conditioning system. Like the rest of the vehicle’s systems, this needs regular maintenance.
Your owner manual will usually tell you exactly how frequently you should check your coolant/water mixture level as well as how often you should flush the radiator. This is usually a fairly simple, straightforward operation.
With flushing, you use the petcock or valve below the radiator to empty the coolant system into a low container you can buy at any auto parts store. This mixture should not be allowed to drain into the ground or even to your garage floor; ethyl glycol, a primary ingredient, can be quite toxic even in small doses, especially to pets and small children. But you also don’t want this in your local ground water table either where it can poison.
Understand that the antifreeze/coolant – always mixed with water per instructions on the bottle – only keeps its integrity for a period of time. Exactly how long is usually listed on both the bottle as well as in your auto owner manual. Also, lots of impurities and debris can build up in the cooling system that can degrade your protective cooling fluid even faster. For these reasons, it is best to flush the cooling system as regularly as your manual recommends. Once you drain the existing coolant mix, you close the petcock or valve on the radiator, add water, usually run the engine for a bit (again, your manual or bottle will tell you), and then drain the water. On a particularly old or poorly maintained vehicle, you may want to perform more than one water rinse. But when the final rinse is complete, you close the petcock or valve again so you can now add the coolant/water mixture in the proper proportions as documented.
Wherever possible, use the same antifreeze/coolant type recommended. This is wise because a very cheap or low grade antifreeze/coolant may not be able to stand up to the cooling demands of a particular engine.
Between coolant changes, you must keep an eye on the level shown on the outside of the coolant overflow tank, usually positioned very close to the radiator. Almost every manufacturer clearly marks the overflow tank to make it easy for you to see when it is time to add more mixture; how often this is needed varies between makes and models. When you need to add more mixture, it is usually done through the top of the cooling overflow tank rather than the radiator. Remember this because you can crack the radiator if, when you notice your radiator is in dire need of fluid, you try to add cold water to an extremely hot vessel.
Whenever you perform your checks, be sure to look at the radiator hoses. Any signs of damage or wear should make you run, not walk, to the auto parts store for a good patch kit if not a fresh hose.
A problem thermostat presents another issue. The thermostat watches temperature and adjusts the flow of coolant mixture, as needed. But a thermostat can become gunked, its aperture can be stuck open or closed which stops temperature regulation, and this device can fail altogether.
Your owner manual may indicate where the thermostat is located. If you can find it and access it, you can usually get a proper replacement and install it yourself. Again, your auto parts store can be great help, there. However, you can also remove your current thermostat and test it.
For example, the aperture on the thermostat, when cold, should stay closed. As the engine heats, the aperture should open. Take your thermostat out of its housing and place it in a very hot cup of water. If the aperture stays closed, you need a new thermostat. But if the aperture opens, the thermostat may be operating correctly so you need to look elsewhere for a culprit.
Beyond the obvious suspects when you experience a problem with the cooling system proper, other auto parts play a big role with heating and cooling as well. Take the fan belt, usually also located near the front of the vehicle, often between the engine block (the part of the car that comprises the main engine structure) and the radiator. When a fan belt loosens or wears, many symptoms arise including loss of power and – important here – jump in engine temperature. Once the belt breaks – and fan belts have a tendency to do just that – your car, truck, or SUV stops dead. If it didn’t, you might have even bigger problems.
The exhaust system can also affect your vehicle’s ability to cool itself. Even before a tail pipe or muffler falls off, the exhaust system can receive serious wear and damage from scraping against potholes and bad roads. The result of this damage often is engine overheating. This makes sense because without a fully operational exhaust setup, heat is no longer properly dissipated out through the exhaust system; this same heat builds under the hood and drives up engine temperature.
Finally, if your problem is not an overheating engine but a failure to get hot or cool air into the passenger compartment, look at the most obvious suspects first. Clogged vents leading from the engine into the passenger compartment can keep air from being exchanged. Vacuuming these vents out or pulling debris from them before you turn the blowers on full blast can usually help clear the vents.