How to Keep Your Automatic Transmission External Cooler Healthy

The automatic transmission is a pretty nifty invention. Very reliable for the most part and keeping it healthy is important. Two of the best ways to keep it going long and strong is clean fluid..and keeping that same fluid cool. This is why your car has a transmission cooler built right in.

This cooler is actually a part of the radiator. The radiator is sectioned off on one end and has fittings that will accept the threaded line coming to it from the tranny. These fittings are attached to internal lines within the radiator. The transmission fluid circulates through these lines and since the lines are immersed in radiator coolant, the heat from these lines can be dumped into the water and carried away.

All well and good until you want to do some heavy duty towing. A travel trailer is a huge load to your vehicle and even a lighter load such as a medium sized boat and trailer can be a big drag especially if you have to do any hill climbing.

A good way around all this is to install an external transmission cooler. This is something like a radiator except it is exposed to the outside incoming air and helps to cool the fluid inside.

Select a cooler that fits your needs and then locate a good place to install it. Ideally, the location should be exposed to as much moving air as possible. Many people will place them just below the front bumper. Once mounted, you will need to disconnect the transmission cooler line at the bottom of the radiator and by means of flexible line ( usually supplied with your new cooler ), connect that line directly to the radiator at the bottom and run it to the external cooler. Next of course you will need to run a line from the external cooler back to the transmission. There should be a flex line in the kit for this and the line is connected to that line you just disconnected at the bottom of the radiator.

What you have here then is a two stage cooler. The hot transmission fluid is first cooled down by the radiator and the fluid coming out of the radiator is then directed to the external cooler for more cooling before returning to the transmission.

But this only half the battle to keeping your transmission running strong. Stop in at a parts store and buy enough of the correct type of transmission fluid to completely replace the fluid in your transmission. Also get a transmission filter and pan gasket. Back at the house drop the transmission pan and replace that filter in the valve body. Replace your pan gasket and reinstall the pan. Now, consult your vehicle maintenance guide and determine how best to drain the fluid from the torque converter. Once that is done and everything is buttoned back up get yourself a funnel and start refilling the transmission. They take a lot of fluid and you may as well get a couple quarts extra to accommodate that external cooler you just put on. Put in about 3 or 4 quarts and then start the engine. This is to circulate the fluid and fill the torque converter and the new external cooler. As you get near the full limit on your tranny stop and use the dip stick to gauge if it is full. Run the tranny through the gears to fully insure everything is alright. Top off the fluid and you are done.

If you will avoid extremes in driving such as burn outs and manual shifting when it is not needed, plus change out that fluid about every 2 years, your transmission will hum along for a good long while. Now wear is inevitable of course but clean fluid is a huge key in the life of the tranny. Fluid is more than the hydraulic method the tranny uses to move your vehicle..it is also a coolant, a lubricant, and is crucial to how well the internal clutches grip and respond. This is why you want to use only factory recommended fluids, and to prevent fluid breakdown, you want to keep it cool. Heat has enormous damage potential to internal seals and gaskets in the transmission. So keep it clean, and keep it cool.