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Basics of the Cooling System

As there is not a Cooling specific section of our forums I will post this here and if it needs to move please do so.

Alright so I have been asked to post up a How-To article about the cooling system works. This is NOT DSM specific but applies to all cooling systems. These are also just the basics of a cooling system, not the complete specifics of each and every piece of the cooling system.

Lets first talk about the radiator. A radiator is just a heat ex-changer. The radiator in a vehicle is designed to take a fluid or air, whether it be engine coolant, transmission fluid, oil, power steering fluid, or even air, and cool it to a lower temperature than what it was before it went in.

There are 2 key parts when it comes to radiators:

The first is the "core". The "radiator core" is the piece of the radiator where all the cooling happens. This is the section where the "fins" are (those pesky little pieces of metal that get bent if a rock, or anything else touches them). With an engine coolant style radiator you have 4 key parts that make up the "core" of the radiator.

-The first is the "fins". These are what take the heat away from the coolant. A crucial part of the fins are the "fin density". This is how many fins are in a given area. The denser the fins, the more cooling capacity the radiator has. Unfortunately you cannot run too dense of fins because then the air cannot pass through the radiator and effectively cool the fins.

-The second is the "pass tubes", which are the size of the tubes that the go from one end tank to the other. The fins then are attached to these tubes. Yes that is correct, the tubes are what the coolant runs through not the fins themselves. The larger the tubes, the more heat being dispersed into the fins which get cooled by the air passing by them.

-Third, but still important, is how many "rows" the radiator has. A "row" is considered one set of tubes running from the end tanks. When you add another "row" it puts another set of tubes either behind or in front of the first set of tubes. This makes it a 2 row radiator and you can keep doing this as many times as you would like to make as many "rows" as you so desire. Back in the day everyone used to say the more "rows" the radiator had the better it cooled the engine. Well now days we have figured out that it is better to run less rows and bigger tubes. This is because of the fact that by the time the air from the first set of rows hit the last set of rows, it would be almost the same if not the same temperature as the coolant inside the tubes, which would not cool at all. This also applies to the thickness of the radiator. Just because your radiator is thicker does NOT mean it is going to cool better then another radiator that is thinner (there are times when it being thicker is better but that is something we will get to).

-The last part of the radiator is the number of "passes". A "pass" is referring to how many times the coolant goes from one side of the radiator to the other. Inside the end tanks of the radiator is chambers. When there is only one pass on a radiator then the end tanks have no chambers. This means that the coolant passes from the inlet end tank to the outlet end tank only once. When you have two passes then there are chambers in the end tanks separating the coolant. This allows the coolant to pass from one side to the other then back. This allows the coolant to pass through another set of "pass tubes" that send it through the radiator again before going back into the engine. This, in turn, allows the coolant to pass through the fins yet again to further cool the fluid.

I said we would talk about the thickness of the radiator so here it is. The thickness of the radiator is a contributing factor, but it is more efficient to run as thin of a radiator with as large of "pass tubes" as possible. Now of course the number of rows and the number of passes is also important, so with the DSM community a good radiator is one with at least 1" pass tubes, 2 rows and a double pass radiator. The thinnest you can get all these things the better. Another thing that someone can do before they make the investment in a new radiator is find the largest core possible (height and width wise) before going thicker. The more core, the more cooling capacity the radiator has. As you might remember from before, once the air gets to the back of the radiator it is hotter than when it first entered. The thicker you go, the hotter the air will be once it reaches the back. (I hope I made this understandable to everyone)

The "end tanks" are the second part of the radiator. The "end tanks" are where the fluid arrives and exits into the radiator. The "end tanks" are basically just a reservoir that feed the "pass tubes" and a place for the coolant to enter and exit the radiator.

When the radiator is working properly this is an extremely effective system to cool the coolant in the cooling system of the engine. A common misconception when you are talking about the cooling system is that the engine is cooled by the air being pushed onto the engine. This is 100% false. The air passing over the engine does nothing for the cooling of the engine in any coolant cooled vehicle.

Well while we are at the radiator, we might as well talk about what attaches to it, the fans. All a fan is designed to do is pull or push air through the radiator so the radiator can do its job even better. A fan is only designed to be used to help assist in exchanging air through the radiator, not keeping the engine cool. The fans should only be used when there is not enough air being drawn through the radiator to sufficiently keep the engine cool. Now there is one important thing to know about fans, not all fans are created equal. Some fans are optimized for high air flow and others are made for static pressure. Now when you are pushing or pulling air through something you need static pressure. If you are just pushing air with nothing in its way, say in your shop, you need high air flow. So as for radiators we need static pressure fans to get the best performance out of your fans and radiator. When you look at fans you are also looking at the cfm's of the fans. This is how much air the fan will push or pull without any restriction. When you try to push or pull air through the radiator you now have restriction so the cfm's will be lower. Although this number is reduced, the cfm's of the fan is still extremely important because the more air the fan will displace, the more air it can then carry through the radiator. I'm not going to go into which fan brands are the best as that is for a completely different discussion, but the overall concept is what matters.

Now onto the next piece of the cooling system in a vehicle which is the "thermostat". The "thermostat" is a device that stops or allows the flow of coolant from the engine to enter into the radiator. The "thermostat" for a given car is rated in *F or *C. This temperature rating dictates when the "thermostat" is designed to open and close. If say a car has a 190* thermostat, this would mean that the thermostat is designed to open, and allow coolant to flow into the radiator at 190*. Any temperature of the coolant below 190*, say 189* or less, the thermostat stays closed and does not allow coolant into the radiator. This thermostat is there to allow the engine to warm up to its operating temperature (in our case 190*) before it needs to be cooled or sent into the radiator for cooling. During the time that you are driving your vehicle, the thermostat is opening and closing to keep the temperature of the coolant, and subsequently the engine, at its optimum temperature.

The next big component of a standard cooling system is the water pump. This pump is designed to displace the coolant in the engine, radiator and hoses throughout the coolant system. A water pump can be engine driven or electric (there are others but for the tech section I will stick to these two). A engine driven pump is just that, it is driven by the engine, either through a belt, chain or other device. This pump pushes water through the system at different speeds based on what RPM's your vehicle is at. The electric motor drives the water in the same way but is driven by just that, an electric motor. This takes the load off the engine allowing the engine to create more horsepower and still be pumping coolant through the engine and radiator. An electric pump also allows you to mount the pump in another place that might be better for the application.

I hope this help you understand some of the different parts of the cooling system of the engine. In the case of the all vehicles I would suggest keeping your thermostat the same temperature that the manufacture states for use in all weather and season conditions. If you are having cooling issues during the summer then your cooling system needs some attention. DO NOT CHANGE YOUR THERMOSTAT THINKING YOUR ENGINE TEMPERATURES WILL DECREASE!!! If you are constantly overheating during the summer and you change your thermostat and that fixes your problem, then there is another issue with your cooling system. Putting in a cooler thermostat will cause negative effects on your engine! For every 10* cooler of a thermostat you install into your vehicle it can reduce the performance, gas millage and life expectancy of your engine by up 10%, if not more. If you have questions, would like to know more about the cooling system, or are having overheating issues and would like to know what you can do, please feel free to send me a PM and I will get back to you.
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