Tuesday, July 23, 2024 Detailed Auto Topics
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Most folks would like to extend the life of their vehicle and many people consider an auxiliary automatic transmission cooler. Sometimes an auxiliary transmission cooler offers benefits. Vendors, eager to make a sales, often overstate what a transmission coolers can do. Unless we properly install the cooler, it may do more harm than good.

The proper automatic transmission temperature

In normal operation the automatic transmission produces a good deal of heat. Much like our body, the proper temperature is important. With transmission temperature, too little or too much shows a problem. An automatic transmission operates at around 175 degrees Fahrenheit, under normal conditions. When the temperature remains lower, moisture may build and the transmission can lack efficiency.

Automatic transmission temperature rising above 175 degrees is also a problem. As temperature rises, the automatic transmission fluid begins to break down and damage occurs. Heat also causes expansion and changes tolerances on internal components. An overheated transmission will quickly fail.

All vehicle manufacturers provide a means for cooling their automatic transmissions. The automatic transmission fluid transports the heat from the internal components and transfers it to the transmission case and pan. Air passing by the transmission case and pan, remove a great deal of excessive heat from the transmission.

Engineers normally provide an external transmission cooler as well. Most vehicles have a transmission cooler built into their radiator. Usually this is more than adequate to maintain transmission temperature.

Overheating may be a symptom of a transmission problem

A transmission cooler will NOT solve an internal transmission problem

Many things can cause an automatic transmissions to overheat. Most important is to find and correct the reasons causing the overheat. With internal problems, simply adding an auxiliary cooler will not help and may hurt.

A clue to diagnosing the problem comes from the history of the vehicle. When our transmission starts to overheat and nothing has changed, the problem is likely internal to the transmission.

A restricted transmission filter may show up as elevated transmission temperature. Fluid is not able to flow through a plugged filter and the pressure needed by the clutches is lowered. Slipping clutches produce heat and debris. Heat breaks the automatic transmission fluid down and debris further restricts the filter.

Internal failures, such as slipping clutches or a bad torque converter, cause the transmission temperature to rise. This is similar to an infection in our body causing a rise in our temperature. An elevated transmission temperature is a symptom of a bigger problem. transmission diagnosis and repair are the answers and adding a transmission cooler will not help.

When will an auxiliary transmission cooler help

A vehicle that we use for towing may sometimes benefit from an additional transmission cooler. Towing increases the load on the transmission, and this produces more heat. A good example is a transmission that stays within the normal range of 175 to 200 degrees Fahrenheit when not towing. An auxiliary cooler may help with temperature that rises slightly above this when towing. An auxiliary transmission cooler will NOT increase the capacity of an overloaded vehicle.

An auxiliary transmission cooler is NOT a silver-bullet

A transmission cooler cannot make up for a truck that is too light to tow the load required

A transmission cooler will not help a truck that is overloaded. Elevated temperature in a transmission is a symptom, as well as a problem. Temperature rising into the 275 to 300 degrees Fahrenheit range indicates a vehicle towing more than it is capable of pulling. A transmission cooler cannot make up for a deficient design.  To tow more weight a more robust vehicle is needed.

Properly installing an automatic transmission cooler

Proper installation is even more important than the auxiliary cooler itself. To operate properly, we must properly install the cooler. Many vehicle makers offer a factory option for a transmission cooler. If our vehicle did not come equipped with this option, we can often purchase the parts and install it. Installing the factory-option cooler prevents many problems. They design the factory cooler to fit the vehicle. When we install aftermarket coolers, several things need to be checked and verified.

Hose problems

It is always best to place the auxiliary cooler inline with, and after the existing radiator cooler. With the factory installation kit, this should be easy, as all necessary fittings and lines are usually supplied. With an aftermarket cooler, lines must often be cut and hoses attached.

A line must have a barb to hold a hose, double clamps will not help

Simply cutting the metal line and clamping a hose to it, is very dangerous. Transmission fluid is the life-blood of the transmission and under high pressure. If the line pops off, the transmission will quickly burn up. Transmission fluid is also flammable and presents a hazard if a line comes off. Double clamps on a line without a barb, will not help.  We must provide a something to keep the hose from slipping off.

a compression fitting may be used to create a hose barb

We can use a compression ferrule to create a barb and prevent the auxiliary cooler hoses from coming off. To do this, we slip the compression nut over the line that we have cut. Next we place a tubing nut on the line and add the ferrule. We can now use a male compression fitting to lock the ferrule to the line. A cutoff tool will remove the compression nut after tightening. The ferule now acts like a barb and the hose will stay in place if properly clamped.

Transmission hose is a specialized product, designed to resist petroleum, heat and pressure. We should only use a hose that specifies, "for transmission use." The clamp is equally important and many hose clamps are substandard. A name-brand hose clamp is a good investment.

improper installation can cause damage to other components

Properly routing and securing the hoses is very important. To avoid chaffing and cutting a hose must be secure and not touch metal body parts. Be careful when attaching hoses to the body of the vehicle. Before drilling holes, check both sides of the panel. Drilling into a brake or fuel line can create a real problem. Check bolts and screws to make sure they do not interfere with other components. This bolt rubbed through the air conditioner condenser and caused an expensive repair.

Mind the gap

an air gap between components in necessary for proper air flow

They design factory transmission coolers with brackets that support them and provide an air gap between the cooler and other components. This gap is necessary for proper airflow. We must mount the auxiliary cooler in front of the air conditioner condenser or any other coolers. We need an air gap between the cooler and the next component. The air gap should provide between one-half and one-inch spacing. This allows for air flow and prevents the cooler from rubbing holes in other components.

Improperly installed transmission cooler adds no benefit

This aftermarket transmission cooler is improperly installed. Attaching the cooler flat, against another component, will result in lack of cooling and other problems. Such an installation may be worse than not adding a cooler. If the radiator cooler is also bypassed, damage to the transmission may occur.

Touching components on a vehicle will wear through, due to vibration

All vehicles vibrate and when components touch, problems will be close behind. The above cooler was attached to an existing brace with a tie strap. The brace will rub through the aluminum cooler and cause a dangerous leak.

Proper installation of an aftermarket cooler

A proper aftermarket cooler installation

This cooler is firmly attached with metal straps, at the proper distance from the condenser. The hoses are clamped over barbs and routed safely. After installation, and when towing, transmission temperature dropped from 225 degrees to 175 degrees Fahrenheit.

If a vehicle is experiencing elevated transmission temperature while towing, an auxiliary transmission cooler may help. With proper installation, an auxiliary cooler may help keep the transmission working for years to come.

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