Servicing Your Engine's Cooling System Copyright AA1Car Adapted from an article written by Larry Carley for Underhood Service magazine Did you know that up to a third of the heat energy produced by an internal combustion engine ends up as waste heat in the cooling system? A gallon of gasoline produces about 19,000 to 20,000 BTUs of heat energy when it is burned,which is enough to boil over 120 gallons of water! So the two or so gallons of coolant that circulate within the typical automotive cooling system have to carry away a lot of heat.Heat exchangers with extremely small passageways are especially susceptible to this kind of problem. Once clogged,heat exchangers are difficult to clean and replacement is usually necessary. The average service life of an OEM copper/brass radiator is six to 10 years crp123,and eight to 12 for aluminum. But even with good care,radiators can fail for a variety of reasons including vibration,mechanical stress and physical damage. Fatigue cracks can occur where the inlet and outlet fittings connect to end tanks,along tank/tube header connections,or where the radiator support brackets attach to the radiator. Excessive heat can kill a radiator,too. Ones with plastic end tanks can be damaged by steam erosion if the coolant level becomes low and the engine overheats. White deposits on the inside of the plastic tank would indicate steam damage. Replacement radiators are available in various styles and materials. What is important here is making sure the replacement radiator cools as well (or better) than the original. Compare the BTU ratings to make sure the replacement can handle the heat. Some"value priced"replacement radiators cut corners to reduce cost,and may not cool as well as the original. For normal driving,this might not be a problem but under heavy load or during unusually hot weather it might increase the risk of overheating. When it comes to cooling capacity,it may be a good idea to upgrade - especially if a vehicle spends a lot of time idling in traffic during hot weather,pulls a trailer or is driven off-road. Aftermarket"heavy-duty"or performance radiators typically have additional rows of tubes,increased thickness and/or a more efficient fin and tube design to improve cooling performance. For some applications,you may also have a choice between an aluminum or copper/brass replacement radiator or heater core. Aluminum is the most common material for newer applications (almost 90% of all new vehicles),while copper/brass is the most common material for older cars and trucks. Copper/brass was used almost exclusively up until 1980s when aluminum's weight-saving and environmental advantages (no lead solder) brought it to the forefront. Some say copper/brass cools better than aluminum,but cooling efficiency depends more on the design of the radiator than the materials in it. The safest approach is to use the same type of heat exchanger as the original. When a radiator is replaced,compare the width,height and thickness to see if any modifications will be needed to make it fit (hopefully,none will be needed). Aftermarket radiators may not always be an exact match with the original because of consolidation (especially if a copper/brass radiator is being replaced with one made of aluminum or vice versa). But as long as the size and location of the hose connections are the same or similar,it should create no installation problems. On some newer vehicles,the radiator is part of a"cooling module"that includes the A/C condenser and fan. Some of these can be difficult to remove and may have to come out from the bottom rather than the top. Separating the radiator from the other components may also be a chore. And if it is a really new vehicle,the radiator may not yet be available as a separate item,which means you have to replace the entire module at added expense. Other cooling system items that may also need to be replaced when changing a radiator include the upper and lower radiator hoses,heater hoses,hose clamps,water pump,fan clutch (on older vehicles with pump driven fans) and drive belts. The old radiator cap should not be reused unless it has passed a pressure test. In fact,most radiator manufacturers say a new cap should always be used if the radiator is replaced. The new cap must have the same pressure rating as the original. If the engine overheated,the thermostat also should be replaced as a precaution to eliminate the risk of a repeat boil over. Overheating frequently damages the wax element inside the thermostat. You also should check the coolant sensor to make sure it has not been damaged. Inspect the thermostat housing and replace it if it is badly corroded,warped or cracked. When you refill the system,use a 50/50 mixture of antifreeze and distilled or deionized water. Hard water that contains dissolved minerals will shorten the life of the additive package in the antifreeze Autel MaxiSys Pro. Softened water should also be avoided because it contains salt (sodium chloride) that increases the risk of electrolytic corrosion. Finally,the hardest part of replacing a radiator (or any other component in a cooling system) is getting all the air out when the system is refilled with coolant. Some vehicles have bleeder screws to vent trapped air. For those that do not,you may have to loosen and burp a heater hose to release trapped air. Service Tip:If an engine overheats after you have refilled the cooling system,there may be some air trapped under the thermostat. An old mechanic's trick is to take a small drill bit (3/32 inch) and drill a vent hole in the thermostat flange before the thermostat is installed. This will allow trapped air to pass by the thermostat. Some replacement thermostats already have this feature,and are called"jiggle pin"thermostats because the vent hole has a small pin in it to seal pressure but also vent air.
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