What to Do When Your Car Overheats

The moment it happens: a calm step-by-step

First, turn off the air conditioning. The A/C compressor adds load and heat to the engine, and switching it off eases the strain right away. Then, if it feels counterintuitive, turn the heater on full blast. The heater pulls heat out of the engine and dumps it into the cabin, which can buy your engine a little relief while you find a place to stop. You will be warm and uncomfortable, but the engine comes first.

Next, find a safe place to pull over and shut the engine off as soon as you reasonably can. The longer an overheating engine keeps running, the more damage the heat can do. If you are stuck in traffic and cannot pull over immediately, shift into neutral or park while stopped and gently rev the engine a little, which helps the water pump and fan move coolant and air. Crawling along is better than sitting still with the engine straining.

Once you are safely stopped and the engine is off, pop the hood release from inside the car, but do not open the hood yet. Let everything cool down. Then call for help. Continuing to drive a seriously overheating car to try to make it home is a gamble that often turns a repairable problem into a replaced engine.

The one thing you must never do

Do not open the radiator cap or coolant reservoir cap while the engine is hot. This is the mistake that causes serious burns every single summer. A hot cooling system is under pressure, and that pressure keeps the coolant from boiling even though it is far above the normal boiling point of water.

The instant you crack that cap, you release the pressure, and the superheated coolant can flash to steam and erupt out of the opening, scalding your hand, arm, and face. Wait until the engine has fully cooled, which can take a half hour or more, before you even think about touching a cap. When in doubt, leave it closed and let a professional handle it.

Why engines overheat in the first place

Overheating almost always comes down to the cooling system failing to move heat away from the engine. The most common cause is simply low coolant, often because of a leak somewhere in the system, such as a cracked hose, a bad radiator, or a failing water pump. If the coolant cannot circulate or there is not enough of it, the heat has nowhere to go.

Other frequent culprits include a stuck thermostat that will not let coolant flow, a radiator fan that has stopped working, or a radiator that is clogged or caked with debris and can no longer shed heat. A worn or broken serpentine belt can also stop the water pump from turning. Each of these has a different fix, which is why an overheating car needs a proper diagnosis rather than a guess.

Once it has cooled down, and how to prevent a repeat

After the engine is completely cool, you can carefully check the coolant level in the overflow reservoir. If it is low and you happen to have coolant or even plain water on hand, topping it off may get you moving again, but treat that as a temporary measure, not a repair. If coolant ran low, it almost certainly went somewhere, and that leak still needs to be found and fixed.

Even if the car seems fine after cooling and topping off, have the cooling system inspected before you trust it on a longer drive. Whatever caused the overheating is very likely still there. The team at Super Tire & Muffler in Cortland can pressure-test the system, find the leak or failed part, and handle a coolant flush or radiator and cooling repair so it does not leave you stranded on State Route 5 again.

The fix you never need is the one you prevent. Keeping an eye on your temperature gauge, watching for coolant puddles under the car, and servicing the cooling system on schedule catch most of these problems long before they boil over on a hot afternoon.