Why Is My Car Overheating and What Can I Do?

Cars overheat most often in very hot weather. It’s rare with modern vehicles, but even a well-tuned automobile can overheat. Although hot weather is the most common cause of overheating, many other factors can cause the same problem. If your vehicle overheats in traffic in normal weather, one of the following may be the culprit:

• The water and coolant and water level in the radiator is low.
• There’s a leak in the cooling system.

Once in a safe location you will want to perform a car overheating troubleshoot.

Always be safe when working on your automobile. Check out these auto repair safety rules to avoid serious injury.

Cooling your overheated engine

If you find yourself in stop-and-go traffic or climbing a steep grade on an extremely hot day, and your dashboard temperature indicator starts to rise or a malfunction indicator light comes on, here’s how to help your vehicle regain its cool:

• At the first sign of overheating, shut off your air conditioner and open your windows: Doing so decreases the load on the engine and helps it cool off.

• If you continue to overheat, turn on the heater and blower: Doing so transfers the heat from the engine to the passenger compartment of the vehicle. (This does wonders for your overheated engine but very little for you!)

• If you’re stopped in traffic and the temperature gauge is rising, shift into Neutral or Park and rev the engine a little: Doing so makes the water pump and the fan speed up, which draws more liquid and air through the radiator. The increased air and liquid circulation helps cool things off.

• Try not to ride your brakes: In stop-and-go traffic, crawl along slowly, on little more than an idle, rather than moving up and then braking repeatedly. Brake drag increases the load on the engine and makes it heat up. If traffic is crawling, move up only when the gap between you and the vehicle in front of you gets too large.

• If you think that your vehicle is about to boil over, drive to the right-hand side of the road, open the hood, and sit there until things cool off. Remember, don’t open the radiator cap under these circumstances, and if your engine has boiled over, don’t add water until the engine is quite cool again.

• If you can't locate any leaks in the cooling system, your thermostat may be malfunctioning. Obviously, you can't replace the thermostat at the side of the road. In the meantime, if you can park and get to the thermostat safely, you can eliminate this malfunction as a possibility. Wait until the engine cools down completely, and remove the old thermostat and reconnect the hoses without it. If the engine starts up and runs well without the thermostat, the old one was probably screwing up the works.

  If you must add water when the engine is still a little warm, add the water slowly while the engine is running in Neutral or Park.

Troubleshooting an overheating engine

The first sign of a car overheating is either when the needle on the temperature gauge pushes its way into the ominous red zone or the “Check Engine” or “Temperature” malfunction indicator light on the dashboard casts a sinister glow. Left alone, the liquid in the radiator eventually boils over, and steam rolls out from under the hood.

If your vehicle overheats often and constantly loses coolant, the problem may be leaks in your cooling system. If your vehicle overheats in normal weather and traffic, you may need to add liquid to the system, replace the thermostat, adjust or replace the accessory belt, or check the water pump.

The first thing to check if your vehicle overheats often is the pressure cap. Sometimes the gasket on the cap deteriorates and lets pressure escape, which causes the cooling system to malfunction. Most service stations can test your cap for you and tell you whether it’s in good condition.

Overheating problems not related to the cooling system

Some overheating problems aren’t related to the cooling system at all. Here are some other circumstances that can cause a vehicle to overheat:

• Late timing: If your ignition system is malfunctioning, late timing may be causing your vehicle to overheat because the spark plugs are firing the fuel/air mixture after the piston moves back down from the top of its stroke. Late timing alone doesn’t cause an engine to overheat by more than a few degrees, but when coupled with other problems, it can bring the engine temperature to a critical point. Have a service facility place your vehicle on an electronic diagnostic machine to check your timing and adjust it if necessary.

• Plugged radiator: Because plugged radiators cut down on the system’s liquid circulation, the system can’t cool efficiently. The remedy is to have a radiator specialist remove and inspect the radiator. If you’re lucky, just steam-cleaning the radiator does the job; if you’re not, the solution may be more expensive.

• Slipping accessory belt: If you can see and reach the accessory belt that drives the water pump, check to be sure that there’s no more than about 1⁄2 inch of give. If the belt seems loose or frayed, you can try to replace it. If you can’t do the job, have a professional deal with it.

• Collapsing bottom radiator hose: Occasionally, a bottom radiator hose begins to collapse under the vacuum that the water pump creates, and the impaired circulation causes overheating.

• Low oil level: A vehicle that’s low on oil tends to overheat because the oil removes from 75 to 80 percent of the “waste heat” in your engine (in addition to doing its other job of cushioning the moving engine parts).

If you’re one quart low in oil and your vehicle holds five quarts, the oil will carry away 20 percent less heat than it should.

Under normal circumstances, you can prevent overheating by checking the level of liquid in the system and maintaining it properly.