Getting hot on cooling systems

A LOT of people spend so much time finding ways to make their engines perform more efficiently or produce more power by adding and installing a variety of gadgets and performance parts, the results of which are sketchy at best. Yet ensuring that your cooling system is performing at its peak yield’s unmatched cooling performance, which results in a better running and more efficient engine.

According to Tommy Teng of DTM Motorsports/Autotechnika, cooling systems for most modern cars are designed to operate within a certain temperature window. For most modern OBDII Japanese cars starting from 1996 onwards, the range at which your cooling system should stabilize, that is your coolant temperature will stay within that range, is between 76 degrees Celsius and 98 degrees Celsius. This window is when your engine is performing at its best. However, just because your engine runs past 98 degrees Celsius doesn’t mean it is overheating. In fact, Lester Wong of HKS Technical Factory/Garage-R Singapore states that for most cars, running up to 100 degrees Celsius on a hot and humid day is normal and that most car’s cooling systems are designed to run even hotter, more so if your cooling system has a 50 percent mix of coolant, which in some cases can run as 105 degrees Celsius hot.

American cars and European cars can run even hotter, as much as 110 degrees Celsius in some cases. The LS-Series V8 engines of the sixth generation Corvettes are designed to run as high as 230 degrees Fahrenheit, or 110 degrees which is its normal operating temperature.

So what are the parts of your cooling system? There are four main parts: the water pump, the radiator, the thermostat and radiator cap. Attached to the water pump is a serpentine belt that is driven by the main crank hub of your engine; as the engine spins, the serpentine belt connecting the main crank hub and the water pump spins, thereby powering the pump to circulate water/coolant through your engine.

You have to make sure that all these main components are properly replaced. Realistically in five years or 100,000 kilometers, there is serious sign of wear warranting a closer inspection and replacement of these parts.

An ounce of prevention, however, is better than a pound of cure as the old saying goes. Hence, it is crucial to use OEM or better parts to ensure that your cooling system is properly functioning, and replace them once signs of serious wear set in, thereby saving your engine.

The coolant and water used is the most misunderstood component of your cooling system. Some people staunchly believe that a 100 percent use of water is the best for running cool. That is true in a test laboratory setting, or in motorsports when cars are running at speed and receive constant flow of cooling air. But in traffic and especially over a prolonged period of use, your water pump requires lubrication provided by chemicals found in most coolants. Coolants also allow your engine to run hotter without risk of overheating. Without lubrication provided by chemicals found in coolants, your engine, particularly the water pump, will start showing pit marks or signs of surface corrosions which will impede the water pump’s performance to circulate your coolant/water mix throughout the engine, causing aeration/cavitation (bubbling) in the water pump and/or thermostat housing.

Bubbles or air pockets do not absorb heat as well as liquids, which will lead to overheating. Lastly, use the purest form of water, which would be distilled water. Mineral water or just plain purified water contain minerals and other particles that might be healthy for human consumption, but are harmful for the engine and the radiator, causing corrosion; and mineral deposits, which can block coolant flow and thereby cause overheating. Use distilled water only. Of course using tap water, even in small amounts in your cooling system will pretty much ensure damage. For coolants, the best tested coolants include Motul’s Inugel coolant, Toyota’s factory fill red coolant and Castrol’s own coolant.

Next is the thermostat. Most people believe that removing the thermostat will allow your car to run cooler. But as mentioned earlier, engines are designed to operate within a specific temperature window. A thermostat ensures that your engine warms up as quickly as possible, preventing it from running rich as most engines operating outside the specified temperature window run rich as a means of safeguarding the engine. The results? More fuel wasted, especially on short to moderately long drives. Tree huggers will hate you for it as well.

Thermostats are also designed to control the flow rate of cooling. Coolant flowing too fast prevents it from absorbing as much heat as possible from your engine, and increase the likelihood of cavitation/aeration in your water pump and thermostat housing. Car manufacturers spend hundreds of millions of dollars developing your engine. If the manufacturer puts in a part, especially on something as crucial as cooling, it has a purpose there so leave it in place! You can run an aftermarket thermostat that is designed to open at a lower temperature range to get slightly lower temperature stabilization points, which is recommended for cars in hot and humid countries, for heavy use such as motorsports or off-road driving where vehicle speeds are low versus the high engine speeds or RPM.

The last point of confusion is the radiator cap. Water boils over at 100 degrees Celsius. When pressurized by 1 atmosphere or 1 bar equal to 14.5 psi, the boiling point of water is raised to 125 degrees Celsius. This is basically absolute overheating, when your coolant transforms from a liquid state to a gaseous state, thereby preventing it from absorbing heat effectively from your engine. A higher pressure radiator cap raises your coolant temperature with a ratio of 1psi = 3 degrees Fahrenheit. Hence, increasing your 1 bar radiator cap to a 1.3 bar radiator car will increase your absolute boil-over point to 132 degrees Celsius. Hence there is some benefit to be gained by using a higher pressure radiator cap. However, the increased pressure will cause further strain on old radiator and coolant hoses, clamps and clips, so make sure when upgrading to a newer, higher pressure radiator cap to replace your hose clamps and clips plus hoses to new items designed for higher pressure.

In the next installment, we’ll look at doing proper maintenance work on your cooling system.