Radiator Maintenance - Bleeding Your Radiator
An overheated car is a car you can't drive. According to howstuffworks.com, most internal combustion engines create enough heat to self-destruct which is why a cooling system is crucial to the proper functioning of your engine. As the major component of your cooling system, the radiator must be maintained to prevent your engine from overheating. An initial step in maintaining your radiator is to check the coolant/antifreeze level. Occasionally after you add antifreeze, there may be pockets of air trapped in the cooling system. This may also occur if you (or a mechanic) flushes the radiator, and it has been refilled entirely.
In either case, a small amount of air will work its way into the overflow within a few warmup/cool-down cycles. This has the potential to create a bubble large enough to block a coolant passage or hose. Consequently, the air prevents the thermostat from opening properly and disrupts suitable water flow through the motor. You may then experience anything from wildly shifting temperature gauges to general overheating. The solution is simple - you need to "bleed" your radiator.
Although the term sounds dire, the process of "bleeding" your radiator actually yields very beneficial results. Unfortunately, there is no single method that works for all vehicles. It's also important to note that improper bleeding can cause a loss of cooling and lead to a damaged engine. The first thing you should do before attempting to bleed your radiator is to thoroughly review your vehicle's repair manual for guidance. If you have an older vehicle or if your vehicle is equipped with an aftermarket radiator, that part should have come with repair and maintenance information as well.
There is, however, some common consensus among mechanics and car experts about simple, effective methods you can accomplish yourself. Always remember to use caution when working with car engines. Importantly, the temperature of coolant/fluid in your radiator gets extremely hot and could easily burn you if you attempt to remove the radiator cap when the engine is hot.
Let It Flow
Some cars have a bleeder valve located in the head or front of the radiator. Its function is specifically for bleeding off trapped air in the head. If it is overlooked, a hot spot could form in the head causing cracks, warping, or burnt valves. Your manual should clearly delineate this point.
According to experts.about.com, jacking-up the front-end (to elevate the radiator filler opening farther above the cooling system) will accelerate the movement of air pockets to the opening, where they dissipate into the atmosphere.
Next, ehow.com suggests that you start your engine, leaving the radiator cap off so the pressure doesn't build up. Let the engine run until it reaches its operating temperature of about 88C. This will probably take about 15 minutes.
Check the level of the coolant. You may find that the level has gone down as the air trapped in the radiator kept the (initial) level artificially high. When this air was released, it opened up more space in the radiator, allowing more antifreeze into the system. Add more water and antifreeze, in the same 50/50 ratio, to top up. As the air bleeds out, the coolant may bubble and spit from the opening on top of the radiator. Be careful as the coolant is now hot. Wait for a brief period then replace the cap.
Finally, if you are uncomfortable performing this type of car maintenance, it is best to take your vehicle into the dealership or to a local mechanic. Either way, proper care and maintenance of you car radiator goes a long way to better car performance and prolong engine life.