Preventing Overheating

Even a new car can suffer from overheating, especially in hot weather. Turning on the air conditioner can raise coolant temperature 10° to 20° at idle. The problem can be worse with a (After market) hang-on air conditioner than with an original-equipment one, because the car's cooling system may not be designed to handle the added load of the hang-on unit. Luckily, most of the newer cars come with a/c as standard equipment. Idling the engine with the transmission in drive also raises cool ant temperature.

To make things worse, new low-emission engines are built to run at higher temperatures. Emission controls incorporate leaner air/fuel mixtures, retarded spark timing, and auxiliary combustion devices, all of which produce more engine heat. And lowered compression ratios, which permit engines to burn lower octane fuels, increase the heat rejection from engine to cooling system. Filling your car with passengers, hitching a boat trailer to the rear, and running your car in bumper-to-bumper traffic or up a long, steep grade on a hot day also can easily boil the cooling system.

You can forestall boiling by installing 50 to 60 percent concentration of glycol-type antifreeze-coolant. That, plus 14-psi cooling system pressurization raises the coolant's boiling point to 256 degrees F, providing an extra boiling protection over a normal mixture.

If your cooling system is sound and if you use the 50 to 60 percent concentration, remember that the temperature warning light will show red long before the system boils. Ignore the light and watch care fully for signs of boiling on older vehicles. On newer vehicles, the warning light or gauge are designed to accommodate the temperatures related to antifreeze.

Turning on the heater and heater fan full blast will not make the car comfort able on a hot day, but it will lower the cooling system temperature by a few degrees. If you are stopped in traffic, shift into neutral and race the engine; the increased radiator fan speed "engine mounted fans"will help cool things down. If the radiator does boil, stop, shut off the engine, and wait until things cool down. Do not undo the radiator pressure cap; that will let more cool ant escape.

Really tough cases of overheating, caused by extremely hot climates or other hard driving conditions, may have to be cured with heavy-duty accessories such as a larger radiator and a transmission cooler. Many such items are optional on a new car as part of a trailer-towing package. They add little to the purchase price of the new car. If you add them later, they will cost more.

Any time you must repair or replace a radiator, consider buying an oversized one. It will greatly minimize overheating. A transmission cooler for an automatic transmission is available for cars with and without built-in transmission cooling. It works by air-cooling the transmission fluid. A transmission cooler is fairly easy to install from under the car, and it helps prevent overheating of the transmission when the car pulls heavy loads such as a large trailer.

Cooling tips

Finally, there are a number of other factors that can lead to overheating. Be aware of them:

Bugs lodged in the radiator air passages block the flow of cooling air. Blow them out with compressed air shot through from the back of the radiator, or brush them off.

Ignition and valve timing have an effect on engine heat. Late timing adds to the heat a cooling system must handle. Have a mechanic check valve timing if you are in doubt about it. A worn, loose timing chain/belt could conceivably slip a notch. It would be accompanied by a loss in power and an increase in fuel consumption and perhaps oil-burning.

A restriction in the exhaust system can cause overheating. Make a vacuum- gauge test.

Air pockets in the system

Using regular-grade gasoline in engines that should have premium can cause over heating, as well as serious engine damage. Do not slavishly follow the car manufacturer's fuel recommendations Some engines require higher-octane fuel than other supposedly identical ones. If your engine knocks,that is, makes a metallic tapping noise , during acceleration, switch to a higher-octane fuel regardless of what the manufacturer recommends. As some engines age and build up internal deposits, their octane requirements go up.

In a stubborn case of overheating, check for dragging brakes. Self-adjusters on the brakes may have done their job too well ,not common, but a possibility. Wheel cylinders rusted by moisture in the brake fluid can have the same effect. Jack up each wheel and turn it to see whether the brakes are dragging. Front and rear wheels should spin freely.

*Just Tap water in the system will over-heat your engine. Water boils at a lower temperature than coo lent. On modern vehicles the warning lights will not register the condition since they are designed for antifreeze boiling temperatures.

* Slipping fan belts, bad fan temperature drives on engine mounted fans can contribute to over heating conditions.

* On radiator mounted, electric fan assemblies, bad engine temperature sensors, radiator sensor or relays can cause over heating conditions.

* In the Hot Rodding World, over heating is a common problem. When you are engine swapping or building a more higher performance engine , you will have to take cooling more seriously. Higher performance, usually means more heat to dissipate. Bigger engines require bigger radiators and more effient water pumps.

* Collapsed Hoses and bad thermostats, can cause many overheating conditions

* Sludge, corrosion and other contaminates can block the vain's in the radiators and heater cores, limiting their effectiveness.


Proper maintenance would solve many of these problems before they become problems


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