Transmission Cooler: The Definitive Guide

As we’ve explained before, transmission overheating creates the majority of problems in a transmission. The ideal temperature for a transmission rests under 170 degrees, and every 20 degree increase in fluid temperature can cut the lifespan of your transmission by up to half! So what factors contribute to an overheating transmission? Let’s see. Lots of heavy towing, stop and go traffic, hot climates, and your vehicle’s type and size are just a few. And while your car’s radiator helps to cool the transmission, it’s also tasked with cooling the engine as well. An overworked radiator is common when either the engine or transmission has trouble cooling down.

If your transmission overheats often, you should consider adding a dedicated external automatic transmission cooler, or transmission oil cooler to some, to help your transmission work more efficiently. So today, we’ll be explaining everything you need to know about the transmission cooler, including how it works, the different types, how coolers are rated, and tips on installing one.

How Does a Transmission Cooler Work?

A transmission cooler is a square shaped and thin component that is typically added to the front of the radiator or the air conditioning condenser. These bad boys have one function: keep the transmission fluid cool and thereby extend the life of the transmission. The way a transmission cooler works is that heated fluid is sent from the transmission to the radiator and then to the cooler, and air moving over the fins of the cooler help to lower the fluid’s temperature, and is ultimately sent back to the transmission in a continuous loop. Coolers also help to cool the engine and power steering fluid.

how does a transmission cooler work - transmission repair guy how transmission fluid flows - transmission repair guy

When properly installed, a transmission oil cooler helps to add extra cooling capacity and protection to your car’s cooling system. It does not affect any other component of your car as its only role is to cool the transmission fluid. If you drive a car with an automatic transmission, you’ll be able to install one as long as there’s room for it. Coolers are not specifically designed for any make or model. An external cooler is recommended if you tow heavy loads, do a lot of stop and go driving, live in a hot climate, or have a vehicle that overheats often. Coolers operate anytime your engine is running, so fluid is constantly cooled while you are driving.

What Kind of Transmission Cooler Do I Need?

This question is pretty easy. You should get the biggest heavy duty transmission cooler that can fit on your car! The larger the cooler, the better it will be at lowering fluid temperature. The plate and fin and the stacked plate coolers offer a larger surface area to cool transmission fluid faster and better, which is why they are so popular. There’s no such thing as cooling transmission fluid too much, so if you can we suggest getting the largest cooler possible that fits in your car’s GVW range.

Types of Transmission Coolers

Designs will differ between manufacturers, but there are three main types. The different types of transmission coolers include the tube and fin, the plate and fin, and the stacked plate. Most automatic transmission coolers are made out of aluminum, which helps to dissipate heat more effectively, and each type has varying degrees of durability and effectiveness. There are also transmission coolers with built-in fans for even more cooling power.

Tube and Fin Coolers – The tube and fin cooler can be distinguished by the tube that weaves throughout the transmission cooler and the turbulators that surround it. The tube is responsible for transferring the fluid around while the fins attached on the outside help to absorb the heat. Tube and fin coolers are often the least efficient type of cooler.fin and tube cooler

Pros:

Cons:

  • Inexpensive
  • Great for older cars 
  • Least efficient type
  • Not suggested for overdrive transmissions

 

Plate and Fin Coolers – The plate and fin cooler can be distinguished by the parallel plates that run horizontally, and looks just like a mini radiator. This type of transmission cooler is more efficient than the tube and fin type, mainly because the larger surface area allows for more fluid to contact the cooling surface. Fluid is forced through each row of smaller plates that help to cool the fluid faster and more effectively.

plate and fin cooler

Pros:

Cons:

  • More efficient than tube and fin coolers
  • Smaller in size and more durable
  • Large amount of fluid is cooled faster at one time
  • Not as efficient as stack plate coolers
  • More expensive

 

Stacked Plate Coolers – The stacked plate coolers are the most popular and efficient coolers. Stacked plates look like plate and fin coolers, but have larger turbulators that offer higher air flow. They work like plate and fin coolers by forcing fluid through the cooling plates to lower fluid temperature faster and better. Stacked plates are also popular because of ease of installation and removal.

stacked plate coolers

Pros:Cons:
  • Larger plates than plate and fin coolers
  • Most efficient type
  • Smaller in size and more durable
  • Large amount of fluid is cooled faster at one time
  • More expensive

Transmission Cooler GVW Rating

An automatic transmission cooler is rated by the gross vehicle weight, or GVW, and range anywhere from ratings of 10,000 pounds to 30,000 pounds and up. What goes into account when calculating the GVW of a vehicle is the base weight of the car, any accessories, the driver, any passengers, and cargo. Car manufacturers will include a GVW rating as a weight limit for your vehicle. To find the right transmission cooler with your car’s GVW rating, you can take this into account:

transmission cooler btu rating chart - transmission repair guy

Best Transmission Cooler Comparison Chart

B&M Coolersb&m logo – B&M’s Super Coolers are their most popular coolers. Made of 100% aluminum and features high end, sturdy stacked plates. There’s probably no need to mention who B&M are, they have provided performance auto parts since the very beginning–as early as the 1950s–and continues to innovate quality parts for racers and automotive enthusiasts alike.

Model NameGVW Rating (lbs)SizePriceRating
B&M 70255 SuperCooler
16,00011" x 5 3/4" x 3/4"$4.5
B&M 70268 SuperCooler
19,00011" x 7 1/4" x 3/4"$4.7
B&M 70264 SuperCooler
24,00011" x 5 3/4" x 1 1/2"$$4.6
B&M 70266 SuperCooler
28,00011" x 8" x 1 1/2"$$4.5

hayden automotive logoHayden Coolers – Hayden has been specializing in automotive cooling products for over 45 years. Located in Grapevine, Texas, Hayden Automotive continues to be on the forefront of automotive cooling technology. Their most popular transmission oil cooler model is the Hayden Rapid-Cool Plate and Fin.

Model NameGVW Rating (lbs)SizePriceRating
Hayden 676 Rapid-Cool Plate and Fin
18,0003/4" x 11" x 6"$4.6
Hayden 677 Rapid-Cool Plate and Fin
20,0003/4" x 11" x 7-1/2"$4.5
Hayden 678 Rapid-Cool Plate and Fin
24,0003/4" x 11" x 9-1/2"$4.5
Hayden 679 Rapid-Cool Plate and Fin
30,0003/4" x 11" x 11-5/8"$4.6

Derale Coolersderale logo – Derale’s products have been specifically Made in the USA since 1946, and offers only the highest quality coolers available. Their most popular models include the Series 8000 plate and fin and the newer Series 10000 stack plate cooler.

Model NameGVW Rating (lbs)SizePriceRating
Derale 13401 Series 10000 Stacked Plate
20,5003" x 13" x 2"$$4.3
Derale 13503 Series 8000 Plate and Fin
20,5009 3/4" x 11" x 3/4"$4.3
Derale 13402 Series 10000 Stacked Plate
22,5005" x 13" x 2"$$4.7
Derale 13504 Series 8000 Plate and Fin
22,50011-1/4" x 11" x 3/4"$4.6
Derale 13403 Series 10000 Stacked Plate
24,5007 5/16" x 13" x 2"$$$4.8

Transmission Coolers With Fans

For even more cooling power, consider a heavy duty transmission cooler with a built-in fan. Best for when installing a cooler in front of the radiator is not an option, for installing in a place with little airflow, for very large vehicles, or when you want the cooler to continue cooling even while stopped.

Model NameSizePriceRating
Hayden 526 Remote Cooler With Fan
13 .8" x 11" x 4" inches$$$4.8
B&M 70298 Hi-Tek SuperCooler Oil Cooler with Fan
10" x 7.5" x 4"$$$$5.0
Derale 15800 Electra-Cool Remote Cooler With Fan
19.2" x 14.5" x 6.5"$$$4.8

Installing an External Cooler

Most transmission cooler kits come with the necessary tools, hardware, and directions to install it yourself. Depending on where you want to install it–the best places are the front of your radiator or in front of the air conditioning condenser–you will need the adhesive mounting pads, the mounting rods, or fasteners (whichever is included) to do so. Follow the directions included to hook up the inlet and outlet hoses properly, this is important because that is how the fluid being sent from the transmission to the cooler is conditioned.

 ***Tips on Installing a Transmission Cooler***

  • Make sure the cooler you buy fits and there’s ample room for the cooler hoses
  • Keep hoses away from any hot or moving parts
  • Install in a place with a good amount of airflow, where rocks and road debris won’t come into contact
  • Make sure the cooler’s fins are parallel with the radiator’s fins
  • Consider adding a fan if the cooler is installed in a place with little airflow
  • Never install a cooler designed with smaller fittings on a larger system (e.g. 5/16″ cooler on a 1/2″ system)
  • More tips on cooler installation here

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