CAR MAINTENANCE - TIPS AND TRICKS

Dealing with an Overheated Radiator

Overheating is one of the most common breakdowns that autos encounter during the summer season. It happens when the temperature of the coolant exceeds the normal operating temperature range of the engine. Overheating has many causes. Idling under hot weather for prolonged periods can wreak havoc on the cars cooling system, because the water pump doesn't turn fast enough. Thus the coolant is not circulated, as it should be. Sometimes a leak may cause the coolant level to drop thus causing the radiator to overheat.

Here are a few pointers for dealing with an overheated radiator:

• Turn off the A/C. If the car is not seriously overheating, this will reduce the engine's temperature. The AC evaporator is located in front of the radiator, and it adds heat to the air going to your engine. The hotter the incoming air is, the less efficient the radiator will be.
• Turn on your heater (set on highest temperature setting, with blower on highest setting). This will be uncomfortable for you, but it will cool the engine by transferring the heat to the air. Roll down the windows, and remember how 'hot' you'll get if your engine needs replacement!
• If you're stuck in traffic, pull over and stop. Unless you're moving, very little cool air reaches the radiator. Open the hood and let the engine cool off. This takes time, so be patient. Use the time to go get a jug of water or antifreeze.
• Check the overflow tank coolant level. If it's empty, the radiator is probably low on coolant.
• Check the pressure of the system by wrapping a cloth around the upper radiator hose and squeezing it. If it's still under pressure (hot) it will not squeeze easily. Wait until it does.
• Place a large cloth over the radiator cap, and carefully release the pressure. Serious burns can result from the hot coolant. If in doubt, wait until the engine cools completely.
• If the coolant is low, start the engine, and slowly add the water or coolant necessary to fill it up. The engine must be running. Adding coolant to a warm engine can crack the block. By running the engine, the coolant keeps moving and reduces the chances of this type of damage occurring.

**  How It Affects Your Car’s Performance **

                     Just like human beings, the car needs to dissipate heat in order to avoid overheating and exhaustion. During combustion, the engine produces large amount of heat - about 4,000 degrees Fahrenheit. This is too much for the engine to bear so a cooling system is needed to keep it at a normal temperature. Cars usually overheat due to a damaged part in the cooling system, especially the radiator, the heart of the cooling system. It is therefore necessary that all its auto parts must be in proper working condition to ensure that the whole system works efficiently.

Aside from the radiator, the cooling system is composed water pump, freeze plugs, head gasket, thermostat, hoses, heater core, fan clutch and radiator fan. All these auto parts have special roles to perform thus the absence of one could significantly affect the whole cooling process and of course, the engine’s performance. Take for example the hose, this may seem to be just an ordinary part but once broken, the coolant can escape and so it’s no longer possible for the system to cool the engine. Even just the cap of the radiator is important. It holds the pressure in the cooing system; thereby, affects its stability.

How does the cooling system of your car work? The coolant, which is a mixture of anti-freeze and water, is the one that absorbs the heat from the engine. It is drawn by the water pump from the radiator and is pumped through engine block and the cylinder head to absorb the heat from the engine and its parts. It goes back to the receiving tank of the radiator through the radiator hose. The radiator has tubes that contain large amount of water and has fin area to allow outside air to pass through. As the coolant spreads over the top of the radiator tubes, it transfers heat to the air.

The performance of your car is greatly dependent on your cooling system. No matter how gutsy its engine is, it can’t work normally without a cooling system. The engine can even be inutile in an instant if it overheats and all other auto parts under the hood can also be damaged. They could melt as the engine burns the fuel inside the combustion chamber and the pistons in the cylinder could expand extremely that they can no longer move to complete the whole process in the engine.

Your car can possibly overheat as well. Engine overheating is one of the most common problems auto users encounter. You can avoid this by adding water to your radiator. So if you notice a problem on a particular part in your cooling system, consult the best auto mechanic in town. But if you think the problem is worst, you may as well replace it right away.

Cooling System Repair & Service

The cooling system is made up of the passages inside the engine block and heads, a water pump to circulate the coolant, a thermostat to control the temperature of the coolant, a radiator to cool the coolant, a radiator cap to control the pressure in the system, and some plumbing consisting of interconnecting hoses to transfer the coolant from the engine to radiator and also to the car's heater system where hot coolant is used to warm up the vehicle's interior on a cold day.

A cooling system works by sending a liquid coolant through passages in the engine block and heads. As the coolant flows through these passages, it picks up heat from the engine. The heated fluid then makes its way through a rubber hose to the radiator in the front of the car. As it flows through the thin tubes in the radiator, the hot liquid is cooled by the air stream entering the engine compartment from the grill in front of the car. Once the fluid is cooled, it returns to the engine to absorb more heat. The water pump has the job of keeping the fluid moving through this system of plumbing and hidden passages.

A thermostat is placed between the engine and the radiator to make sure that the coolant stays above a certain preset temperature. If the coolant temperature falls below this temperature, the thermostat blocks the coolant flow to the radiator, forcing the fluid instead through a bypass directly back to the engine. The coolant will continue to circulate like this until it reaches the design temperature, at which point, the thermostat will open a valve and allow the coolant back through the radiator.

In order to prevent the coolant from boiling, the cooling system is designed to be pressurized. Under pressure, the boiling point of the coolant is raised considerably. However, too much pressure will cause hoses and other parts to burst, so a system is needed to relieve pressure if it exceeds a certain point. The job of maintaining the pressure in the cooling system belongs to the radiator cap. The cap is designed to release pressure if it reaches the specified upper limit that the system was designed to handle. Prior to the '70s, the cap would release this extra pressure to the pavement. Since then, a system was added to capture any released fluid and store it temporarily in a reserve tank. This fluid would then return to the cooling system after the engine cooled down. This is what is called a closed cooling system.

.RADIATORS : Radiators have been part of cars since the very earliest days and still serve essentially the same purpose now as they did back then. However what they are made from, how they are made, the demands on them and how they do their job has changed as much over the years as the cars themselves have.

As we all know the prime role of a radiator is to keep the engine at an efficient and safe temperature, but increasingly the radiator is also called upon to maintain the automatic transmission’s temperature and even to deal with the heat load in the engine’s oil.

Current radiators are very different in construction to their ancestors. For many years radiators were made from metals such as copper and brass, were comparatively large and heavy and held many litres of cooling water.

But the evolution of the car means that radiators must now be smaller and lighter, while their cooling performance must be greater than ever before, and all this must be achieved with less coolant.

Even as recently as 10 years ago it was still common to find car radiators manufactured from copper and brass. But almost without exception they are now made with light aluminium cores, while plastic tanks are the norm. Aluminium is now the favoured material because it is light and has excellent heat transfer properties. 

As already mentioned the radiator keeps the engine at a safe temperature.  To do this coolant is pumped through the engine’s cooling passages, collecting heat as it goes. The coolant then leaves the engine via a (radiator) hose and travels to the radiator where it passes through a series of finned tubes.  The fins are to increase the surface area of the tube to allow the heat to “radiate” away, hence the name.  The “cooled” coolant is then returned to the engine via another hose to repeat the cycle.

Radiators are remarkably reliable considering the environment they work in. They are regularly exposed to internal temperatures that can range from below zero to well in excess of 100° C and operating pressures that can exceed 100kpa.

But that isn’t to say that radiators are immune to problems. In fact like any other part of the car, they need to be maintained to ensure trouble free service.  This includes changing coolants at the designated intervals and the use of the appropriate coolant for the application.

From an owner’s point of view, radiator maintenance is limited to ensuring that dirt, leaves or grass does not restrict airflow through the core. Unrestricted airflow is important as it is the air travelling through the fins and around the tubes that removes the heat from the coolant. No matter how good the radiator, it can’t work efficiently without proper airflow. Such build-ups can usually be flushed from the core by training the water from a garden hose through the core from the engine side of the radiator.

Obviously the engine should be cold and not running when you do this.

If your car is fitted with air conditioning it will most likely have what looks like a small, thin radiator in front of the engine’s radiator.  This is the air conditioner condenser and it removes heat from the air conditioning system in much the same way the radiator does for the engine.  It’s important that you check that there is no build up of debris in front of the radiator or the condenser as this can affect the efficiency of both.

More serious maintenance involves cleaning the tubes of the radiator to ensure coolant flows freely.  This is a job that requires the services of a specialist and necessitates radiator removal from the vehicle and the removal of one of the radiator’s tanks so a metal rod can be passed through each tube to remove any blockages.

Blockages of this type can occur from inadequate servicing of the cooling system, but over time scale can build up even in well maintained cooling systems.  Scale induced radiator blockages commonly occur after an engine has been overheated as the overheating event can loosen scale formations in the engine block that become lodged in the radiator tubes. 

Another common cleaning method is called “Power Flushing”.  This involves the use of water and compressed air to remove scale from the system.  But while power flushing can be effective in removing loose deposits from the engine block, the disadvantage is that there is no way of knowing how effective it has been in removing radiator blockages.

Other common radiator problems include deterioration of core fins, corrosion of aluminium cores, impact damage, cracking of metal tanks and failure of plastic tanks.

Copper and brass radiator cores are prone to corrosion of the fins.  This is all the more common in areas where the vehicle is exposed to high levels of salt air and there is little that can be done to prevent it.

Aluminium cores are very thin and are susceptible to internal corrosion if improperly serviced and it is relatively common to find aluminium cores that have corroded from the inside.  Such damage is generally not repairable and a new radiator is required.

Another problem that results in similar damage is known as “Stray Current”.  This results from electric current travelling through the coolant and moving small amounts of metal from one place to another.  It is reportedly caused by inappropriate earthing of electrical equipment, or the omission of earth straps after body or other repairs.  

Brass radiator tanks are often found to be cracked and unable to hold coolant.  This is most commonly caused by the constant expansion and contraction of the metal as it heats and cools.  Plastic tanks are also prone to cracking, however in their case it is due to deterioration of the tank material due to age and the effects of heat.

Plastic tanks, particularly the top tank that is subjected to the greatest heat load, commonly deteriorate and need to be replaced once they reach around seven to eight years of age.  Unfortunately plastic tanks often fail with little or no warning leading to overheating that can destroy an engine.

New V Re-cores

There are generally two options when it’s time to replace a radiator.  One is to buy a new OE (original equipment) radiator and the other is to have your radiator re-cored.  Re-cored means taking the tanks and brackets from your old radiator and fitting them to a new core. 

Like most automotive repairs it’s important to shop around for the most cost effective option and to take professional advice on the most suitable long-term repair for your car.

This advice has been prepared as a guide only. Individuals should carry out their own investigations to satisfy specific requirements or situation.