Maybe surprisingly, even during routine driving, the automatic gearbox fluid heats up much more than engine coolant. Also, the temperatures of the transmission fluid might become a serious issue if you race or tow your car. This is because as soon as the transmission fluid overheats, it loses its ability to lubricate, which may quickly cause your gearbox to fail.
But, if the transmission fluid is excessively cold, the same thing occurs. Thus we will discuss the various transmission cooling methods and the flow direction. But first, a brief response to the basic query before we go into more depth and cover all the major broadcasts.
Most of the time, the cooler’s bottom is the cooler return line, while the cooler feed line enters the cooler from the transmission (flowing from the cooler into the transmission). And that is the flow direction for the transmission cooler. No standards govern whether the line is the feed or return on the transmission side. Therefore you must verify your particular transmission.
The direction of Flow for the Transmission Cooler
The top hose connection on the transmission cooler is the hotline, and the bottom is the cold line, as previously described. The fluid entering the transmission is on the cold line, while the fluid leaving the transmission is on the hotline.
That’s only a generalization, so it may be the other way around in certain circumstances. However, some coolers feature an inlet and an exit on the top of the cooler, which contradicts our previous hypothesis.
You may thus check to see whether there are any marks adjacent to the hose attachments to prevent making a mistake. For instance, the flow might be indicated by in and out or inlet and exit adjacent to the hose attachments.
In other situations, a hose or hose fittings may be colored blue and red, in which case the blue would travel to the transmission, and the red would flow to the chiller. Moreover, if you just purchased an aftermarket cooler, you may look up the flow direction in the handbook that came with it.
You may also check the hose temperatures to see if the cooler is already mounted on the car and working. You can determine which hose is warmer by touching them, but only when the engine is completely cool since these hoses may burn you.
Instead of using your hands, you might purchase or rent a laser thermometer. And if you choose this approach, the cooler line feeds the cooler, while the hotter line returns fluid to the transmission.
Next, you may locate the cooling hose attachments on your gearbox and trace them back to the cooler to verify the cooler flow direction. You may locate it by searching online, purchasing a repair manual for your particular model, or seeing whether your transmission is listed in the list below.
Various Transmissions Have Varying Transmission Cooler Flow Directions
The accompanying graph shows a return and feed line for each transmission. The lines from the cooler into the transmission are referred to as the feed line, and the lines from the cooler back to the transmission as the return line (cold line). Moreover, hummerforums.com is the source of this information.
Different Transmission Cooler Types
Heat Exchanger
The gearbox cooler is usually a part of the coolant radiator in autos. The transmission fluid is forced via a conduit with hollow walls on the radiator’s cold side. The coolant then travels through and over the pipe since it is located within the radiator, removing heat from the transmission fluid. Since the coolant is still hot even though it is colder than the transmission fluid at operating temperatures, this method also helps warm up more quickly.
Also, it is inexpensive and simple to manufacture this kind of cooler. But, if the pipe’s walls fracture, transmission fluid may mix with coolant and cause several issues with the engine, particularly the gearbox, as a result.
Moreover, this system’s cooling capabilities fall short of those of a separate transmission cooler. Also, the warmth of the transmission fluid is transferred to the engine coolant, slightly raising operating temperatures—never a good thing—for the engine. Nonetheless, the method is effective enough for the majority of OEM applications.
Plate Cooler Stack
A stacked plate cooler is a freestanding cooler. This means the gearbox fluid does not interact with the engine coolant as it passes through a separate radiator. If anything, this system is too effective in cooling the transmission fluid.
This system’s sole drawback is that it may cause overcooling and delay the transmission fluid’s warming to operational temperatures. However, a thermostat may be installed to lessen the effects of this. Additionally, the transmission fluid radiator is commonly located in front of the engine radiator, inhibiting airflow. Nothing, however, tops a freestanding cooler with a thermostat and a suitable position on the side of the bumper.
A Stacked Plate Cooler with a Radiator Cooler
The ideal option for individuals looking to enhance the cooling capabilities of the typical coolant radiator system is a radiator cooler combined with a stacked plate cooler (transmission fluid radiator). Installing an independent radiator for transmission fluid and feeding it via a regular radiator cooler is how it works. In other words, much as in the typical OEM system, the transmission fluid goes into the radiator cooler (coolant radiator) for initial cooling.
After leaving the radiator, the cold transmission fluid enters an exterior transmission cooler radiator, which receives further cooling before returning to the gearbox. As a result, the transmission fluid undergoes two cooling processes—once via the inbuilt cooler and once through the aftermarket external cooler. Another advantage is this system’s ability to quickly reheat the fluid to operational temperatures while maintaining fluid cooling under heavy loads.
Does One Need a Transmission Cooler?
Undoubtedly, a transmission cooler is required. The transmission fluid is fundamentally identical to engine oil, except that it is denser and loses its lubricating capabilities when it becomes too hot. Currently, the fluid may reach 350F (175C) even with a transmission cooler; without one, it would start to burn within minutes.
Exist transmission coolers in all cars?
Not all cars have gearbox coolers, however. Practically no factory-built manual gearbox car has a transmission cooler. Notwithstanding some exceptions, all automatic vehicles do have transmission coolers.
What Makes an Oil Cooler Different from a Transmission Cooler?
Both an oil cooler and a transmission cooler function primarily to cool oil. An external engine oil cooler or radiator is meant by the term “oil cooler,” They are a common addition to performance automobiles. On the other hand, a transmission cooler has the same appearance and performs the same function, but it cools transmission fluid or oil rather than engine oil.
Does the Performance of a Transmission Cooler Increase?
No, a transmission cooler does not immediately enhance performance. However, if you race the car, the gearbox can be prone to overheating, which would cause the car to go into limp mode. And a transmission cooler may assist in avoiding that and extending the life of your transmission.
Usage of Coolant by Transmission Coolers?
In other words, coolant does not flow via the transmission cooler lines and is not used directly by the coolers. Nevertheless, OEM transmission coolers often mount within the radiator, where the coolant circulates over the pipes holding the transmission fluid to cool and reheat it.
What Location Does the Transmission Cooler Have?
You can’t see the OEM gearbox cooler since it’s hidden within the radiator. But, if your vehicle has one, the external transmission cooler may be in front of the radiator, within the wheel wells, next to the radiator, beneath the vehicle, etc. Everywhere there is excellent ventilation.
What Is the Price of Installing a Second Transmission Cooler?
Depending on your automobile, installing an aftermarket gearbox cooler might cost between $100 and $800. Figuring out where to attach a new cooler within the bumper is the largest challenge, which may require a lot of manufacturing, trial-and-error, and labor hours.
Can an Engine Overheat Be Caused by a Transmission Cooler?
A failing gearbox cooler may lead to an overheated engine. There will be heat transfer from the gearbox fluid to the coolant since OEM coolers are installed within the radiator, but not enough to cause the engine to overheat. But, if the cooler inside the radiator develops a fracture or begins to leak, transmission fluid will enter the coolant, which may soon cause overheating.
Conclusion
Ultimately, it might be difficult to determine the transmission cooler flow direction without a thorough inspection, accurate temperature data, or marks on the cooler itself. Yet, as a general rule, the cooler’s top line exits the transmission while the bottom line returns to the transmission.
You may use our chart, which lists all major transmissions along with what the two cooler hose attachments on them do—feed or return into the cooler—to assist you. And maybe our illustration can clarify how various transmission cooler systems function.
