Note: Allpar does not take responsibility for the veracity of any information or opinions here, does not claim expertise, and is not responsible for any consequences. Please proceed at your own risk.

Cars by name
Trucks and Jeeps

Engines / Trans
Repairs / Fixes
Tests and Reviews

Adding a Neon transmission fluid cooler

Adding a transmission fluid cooler to your Plymouth - Dodge - Chrysler Neon

Note: we suspect the process is similar for other vehicles.

Since I found out about transmission coolers effects on cars that is the doubling of transmission lives in cars, I purchased a transmission cooler, and installed it myself. I am going to go through the process step, by step. 

First things first, go to a local parts store and purchase the compact size transmission cooler. The cost should be around $30 plus tax, just buy it, don't search the web like me, I didn't find it much cheaper than that, and it took me three weeks to do it!!!!

Now that you have the transmission cooler let me tell you what you will need to install it.

Your ever trusted Rachet/socket/wrench Set, and a car creeper (skate board)

There are instructions on how to install this cooler in the box with the cooler (usually) so I won't go into complete details on how to install it. I will tell you the specific area that I installed it, and how I did it, because I saw no other reasonable way to do it!

  1. Jack up the car and safely support it, raise it as much as you can right now
  2. Remove the entire battery box assembly (steps below)
    • disconnect and isolate the positive and negative terminals
    • remove plastic top part of the box (carefully)
    • remove the battery
    • there are 5 or 6 bolts holding the battery box in place, remove them all and the temperature sensor, and air snorkel, and remove the entire battery box assembly. (this is also a good time to relocate your battery to the trunk, if you are planning on it)
  3. Now you should be able to see the transmission plainly (admire for a moment all the space in the engine compartment, wow.)
  4. You should see two (2) tubes for transmission fluid, and use one of them, the closest one as the installation tube for the transmission cooler. 
  5. Now you have to search for 2 gaps big enough to get the tubes to the transmission cooler just in front of the radiator where it will be installed slide the tubes through 2 gaps, one at the top of the radiator, and one at the middle section, just search with your fingers, if you find a hole big enough to stick you finger through, then that should be a big enough gap.
    • Do not install the tubes underneath the plastic air dam, if you bottom out you could tear the tube(s) and loose all your transmission fluid in a few minutes and burn out your transmission. take my advice spend a few minutes just searching, you will find the right spots.
  6. Place the transmission cooler, and install it in front of the radiator closer to the top and use the metal cross members (resembles a wishbone) as the site to install the tranny cooler.
  7. Just follow the instructions on the transmission cooler box, or instruction sheet. 

Transmission cooler feedback

Vince Spinelli added:

All lubricants have an optimum operating temperature. For that reason, virtually all automatic transmission equipped vehicles have a transmission fluid cooler built in from the factory. Typically, it is integrated into the stock radiator... one chamber (typically the upper) in the radiator services the engine coolant, while another services the automatic transmission fluid. The most recent vehicles (say 2000 and newer) may use a very small “waffle,” just off to the side of the radiator, as a dedicated cooler.

If you do choose to install a cooler, do not, let me repeat, do not bypass the factory cooler. Your intention is to add additional cooling to the system, not replace an engineered component (the factory
cooler). As such, what you do is just what Perry did. Trace your tranny lines, and determine which one is the SEND line, going into the factory cooler, and which one is the RETURN line.

--A-- Pull the RETURN line off the factory cooler, and jump it to one end of your added aftermarket cooler.

--B-- Get a fresh piece of hard line or hose, and jump from the other end of your cooler to the RETURN nipple on the factory cooler (where you just pulled that RETURN hose off).

--C-- Make you sure mount the cooler in an intelligent place. In front of the factory radiator is good. In front of the air conditioning condenser is good too (the “other thing” that looks like a radiator, but isn't). On your fender, or anywhere that is not directly inline with the vehicle fan is NOT a good place. In fact, you could end up heating your tranny fluid that way.

4- Unless any of the following conditions are met, then the factory transmission cooler, small as it may be inside of the radiator, is sufficient for keeping transmission fluid within a good working range (with respect to the optimum temperature):

  • The vehicle has been designed poorly or suffers from a design flaw, and you have observed that transmission fluid temperature is well above the optimum temperature for your specified fluid. I believe this is the case of our above friend with the Neon.
  • You have “hot-rodded” your vehicle (and by that I mean more than a cold air intake and cat-back exhaust — internal engine modifications). If you have done the research to determine that your transmission can handle the motor’s output, you will likely also have done the research to determine the necessary additional temperature differential.
  • You have a Light Duty Truck or Sport Utility Vehicle that is mainly aimed at grocery-getting moms and dads... and you regularly tow a trailer (or carry a sufficient load within the bed) that is near or at the manufacturer stated capability of the vehicle. Someone falling into this category, for example, would be an owner of a 2007 series Dodge Ram 1500 Pickup, with a 4.7L V8 and the typical 45RFE tranny. This driver can pull 3,900 pounds with no problem, but if he tows a boat, he’s pulling a 3,500 pound boat trailer, with a 3,900 pound rated vehicle. He’s going to need a tranny cooler, but he has to get one that's just large enough to help out while towing, but small enough that he's not 'over-cooling' the fluid during the other 6 days of the week. Typically, the transmission oil cooler available from Chrysler (or whoever manufacturers your vehicle) as an option on the “Towing Package” for that particular vehicle will be a unit that meets this “just big enough to do the job, but small enough to not cause problems” mark. And, if you're cheap (like me), you just get the size and delta-T specification of the dealer offered unit, and then search the internet for an aftermarket unit with the same specification at 1/5th the price.

If you don't fall into one of the above categories, adding a transmission cooler may likely cause the transmission lubricant to never reach its optimum operating temperature, which results in increased friction, and can lead to failure.

Got a Stick?

Most standard shift transmissions do not have lubricant coolers. This is largely due to the fact that the efficiency of a constantly engaged standard shift transmission is far greater than any automatic. Even the finest automatics rely on a slippage principle, creating heat. (You may be surprised that a torque converter, when operating, is a big ol' ball of heat). However, in severe duty, even a stick is going to heat up.

In such a case, there exist what are basically just giant heat-sinks, cast aluminum shrouds which bolt on to the transmission casing, with large fins to promote greater air cooling. There also exist a few fluid cooling kits for standards. It is important to note that, if one is to perform such a modification, that a skid plate is highly recommended. An exposed tranny line coming off the bottom most portion of the casing (which is where the drain plug hole is at), is a recipe for disaster, unless it is protected.

Newest Ram Built to Serve models honor the U.S. Air Force

Former Ram chief engineer Michael J. Cairns
2021 Ram 1500 Rebel navigation screen
What’s new for ’21? The big list of changes

More Mopar Car
and Truck News