5 Symptoms Of A Bad Transmission Cooler (& Replacement Cost)

The transmission cooler keeps your transmission at optimum temperatures. If it goes bad, it may cause some serious issues. Here's how to tell if yours is bad.

Symptoms Of A Bad Transmission Cooler

The transmission cooler is an added component that works with the radiator to draw heat from the fluid. While not every vehicle includes a stock transmission cooler, it’s vital that you keep this part in good condition if you have one. With a bad transmission cooler, the heat won’t be absorbed properly, causing more wear on your precious gearbox and engine.

We will cover the top five symptoms of a bad transmission cooler and discuss how much it will cost to replace one. Let’s begin with a look at the signs.

Symptoms Of A Bad or Clogged Transmission Cooler

The most common symptoms of a bad or clogged transmission cooler are fluid leaks and an overheating transmission. You may notice strange shifting issues or noises coming from the transmission. In many car models, you will also notice a warning light on the dashboard.

Here is a more detailed list of the signs of a bad or clogged transmission cooler to look for:

1. Transmission Fluid Leak

Car Oil Leak

The most common symptom of a bad transmission cooler is when a leak occurs. There are lines running to and from the cooler that can crack or break. In this case, the line can simply be replaced, which is a quick fix.

The cooler lines can also start to rust. This occurs most frequently if you live in a humid climate or near the ocean. Transmission fluid is bright red in most vehicles, so it is easy to spot. 

2. Poor Performance

Slow Car Acceleration

When the transmission cooler fails, it’s possible to lose fluid, which can lead to poor performance. You might start having trouble shifting if the transmission fluid drops below normal amounts.

Whenever the transmission acts funny, you want to have it looked at right away. What might be a simple problem could quickly turn into an expensive repair if it’s not taken care of. 

3. Strange Transmission Noises

Noise From Car

If there is trouble shifting, this problem could be accompanied by unique noises. Your transmission has many moving parts that must have the right amount and temperature of the fluid inside. 

When the fluid is sacrificed, parts could start rubbing together, leading to strange sounds. You might hear grinding during a shift change or clunking. 

4. Increased Temperature

The entire purpose of the transmission cooler is to reduce the heat in the fluid as it passes through the system. When the cooler can’t work right, it leads to higher fluid temperatures.

When the transmission becomes too hot, other problems follow. This is what often causes lines to break and performance problems in the first place. There could be a clog in the cooler causing higher temperatures or it could just be going out. 

When the transmission fluid starts to get hot, you might also smell burning. If this smell occurs, make sure you stop the vehicle and have it checked out immediately. 

5. Dashboard Warning Light

Your vehicle is equipped with many warning systems, telling when something isn’t working right. When the temperature of the transmission fluid skyrockets, it may cause a Check Engine Light to come on.

This warning is meant to get your attention. If it comes on, have the system scanned with a diagnostic tool to determine if the transmission cooler is going bad. 

Transmission Cooler Location

Transmission Cooler

The transmission cooler is typically mounted on the radiator, where it can achieve maximum airflow. Another type of transmission cooler is sometimes mounted on the air conditioning condenser. 

You can also have a transmission heat exchanger, which is using coolant to cool the transmission fluid. These are often installed on the transmission.

However, all vehicles are equipped with a transmission cooler from the factory, but many users choose to upgrade to a better option down the road. These components are most important with high-performance vehicles or when towing occurs frequently. If you push your vehicle beyond normal limits, you might decide to install an aftermarket option for better performance. 

The Function of a Transmission Cooler

Transmission Oil Cooler
Transmission heat exchanger

The transmission cooler removes excess heat from the transmission fluid. This fluid is needed to reduce friction in the transmission components. There is a lot of friction when gears change, but the fluid keeps everything operating smoothly.

With this friction, heat is generated. To cool the fluid, it travels through the transmission cooler, where it can be dispersed with the help of the radiator and coolant before returning back to the transmission. If you have a transmission cooler located on the air conditioning condenser, the fluid is cooled with the help of this system instead. 

Transmission Cooler Replacement Cost

The average transmission cooler replacement cost is between $100 and $300. Parts shouldn’t be more than $200 with most vehicles, with labor adding in another $100. If you need to replace a transmission cooler, the process isn’t difficult.

You can remove the old cooler and replace it with an aftermarket option, which saves you on labor. 

However, if you plan to install an aftermarket transmission cooler for a boost in performance, you will have more work to do. In this case, you will need to run lines and find an appropriate mounting location. For these situations, you might do better having a professional mechanic work on the system.

Conclusion: Bad Transmission Cooler Symptoms

The main symptoms of a bad or clogged transmission cooler include:

  • Transmission fluid leak
  • Poor performance
  • Strange transmission noises
  • Increased Temperature
  • Dashboard warning lights
Magnus Sellén
Written by:

Magnus is the owner and main author of Mechanicbase. He has been working as a car mechanic for over 10 years, and the majority of them specialized in advanced car diagnostics and troubleshooting. Certified Automotive Diagnostic Technician.

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