Transmission Cooler Line Broke While Driving: What Do I Do?

Do you smell a particular burning smell that comes out of the transmission fluid? Additionally, your car seemed to stop. Before it would show poor shifting response. 

But now it won’t budge a little. Then it’s time to check the transmission cooler line. There’s a high chance that it got broken.

So what to do if the transmission cooler line broke while driving?

If your transmission cooler line breaks while you’re driving, first park your car. Stop the engine and take a look at the transmission to figure out the problem. If the fluid is leaking from a small crack or hole simply seal it. If the crack is non-repairable then change the line with an adapter.

Wanna know the detailed procedures? We’ve covered all of it. So, keep reading until the end to figure out what step to take next!

What Happens When a Transmission Cooler Line Breaks Down?

Transmission cooling lines are used to keep the transmission attached to the car’s radiator. It is a very important tool for the car engine. 


As we know, a car’s engine gets very hot when it’s functioning. The fluids that run the car’s engine can easily get hot. But when the temperature rises too much it hinders the engine’s performance.

That’s why transmission cooling lines were designed. Its functionality is to draw the fluids into the radiator through a hose. A radiator cools down the fluid and returns it to the transmission.

Like all other mechanical parts, a transmission cooling line can get damaged. That results in the leaking of transmission fluid. If it breaks down while driving, it could be fatal for your engine.

So the first thing you should do is to stop the car. You may think you can go a few more miles before reaching a repair shop. But the more you drive the worse it’ll be for your car engine.

Rather than driving, how about you study the problem and look for a solution?

What to Do if Transmission Cooler Line Breaks Down

Since the transmission cooler line has broken down you’ve to fix it. If the condition isn’t very complex you’ll be able to fix it easily. But if it’s unrepairable, then replacement is the only choice.

Whichever the case is, you may need some instant solution to this issue. We’ve included some repairing processes below.

Using Teflon Tape

The first step of repairing any tool is to observe its condition. First, figure out how badly the transmission line has been damaged. Sometimes it’s just a hole in transmission line that makes all the fluids leak out.

If that’s the case you just have to close off the hole to stop the fuel leak. Remember, stop the leaking first, even if you have a small amount of fluid left.

It would be easier if you have a transmission cooler line repair kit at hand. Even if you don’t, a roll of Teflon tape will be enough. It would cost you just a few dollars. Use the tape to seal the part where the transmission fluid is leaking.

However, it’s only a quick solution to your problem, not a permanent one. So, better would be getting your car’s transmission line properly repaired.

Using Rubber Hose

Using a rubber transmission hose can be a quick solution to your problem. But you’d be needing rubber hoses that are specifically developed for transmission. 

Although they are not heat resistant, they are still better than normal rubber hoses. Remember that it’s only a quick remedy and not a long-term solution. 

If you keep the rubber hose for longer it may melt and cause leakage of the transmission fluid. It may cause damage to the gearbox. That’s why it’s a preferable method to go with.

So, use this method only if you don’t have other options open.

Finding a rubber hose specifically suitable for this task hard to come by? Well, you should look at our recommendations:

Briggs and Stratton Heavy-Duty Rubber Garden HoseBuy Now
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We found great success while trying out these rubber hoses. Try them out!

Using Adapter

Using an adapter is an alternative solution to replacing transmission cooler lines. Replacing the whole thing might be complex for someone who’s dealing with it the first time.

So it’s an easier and also a cheaper solution. A piece of transmission cooler line adapter will cost you very few bucks. It’s a lot cheaper compared to replacing them with the real thing.

Also connecting it wouldn’t be a big issue. Because the end of the adapters is made compatible with the transmission and radiator. So you can simply use a wrench to tighten up the connection.

The good part of this method is that the solution is reliable. Adapters are not like rubber transmission hoses. It won’t melt with extra heat. Because it’s heat resistant.

So, if replacement is not possible right away, go for a transmission line adapter.


Replacing Transmission Cooler Line

Replacing the cooler line is the last option in serious moments. If the damage isn’t big, you’d try all the quick solutions you can think of. But what if the damage is beyond repair?

Maybe the transmission cooler line blew off or the scratch is too big to seal. In that situation, you’d have to replace the cooler line. An adapter can be a good solution to the problem only if available.

But in case it’s not, proceed with the real transmission cooler line. You’d also have to replace the washers, fittings, o-rings, and clips. So, let’s get started!

Step-1: Removing the Cooler Line

The transmission cooler line has one end connected with the transmission line. The other side is connected to the radiator. First, open up the side that is connected with the transmission.

Remove the plastic clip. Use a pick or a screwdriver to locate the metal clip attached to the grooves. Now place a bowl under the connection line to collect the transmission fluid.

Because the fluid should not fall onto your car gears. Now, use a hammer to slowly punch it off the connection. 

The other end connected to the radiator must be disconnected the same way. If both sides come off, spin and wriggle your car’s cooling line.

Step-2: Replacing the Cooler Line

Before replacing, you need to clean the connection part of both ends. You can use the same cleaning materials used for cleaning fuse box terminals

For replacement, first, you’ve to connect the part that goes inside the radiator. 

Place the metal clip on the grooves. Now, insert the hose to its position and connect it to the radiator’s fittings. Make sure the connection is tight enough. 

Then attach the plastic clip that’s on the outside. Repeat the same process with the part that goes to the transmission as well.

Step-3: Testing

If the replacement is done it’s time to check for leaks. It would also tell if your transmission cooling line connection was done properly or not. Some vehicles might make noise even after repairing. 

It’s a common transmission problem in 2004 Mazda MPV. Mechanics will take a look at the transmission after repairing to see the whole outcome.


For that, you need to start up your vehicle and check both connecting ends. If there’s no leak coming out that means the connection is safe. 

But if you see any leaking, you’d need to undo the connection. Then look for the problem. If everything goes right, simply put back the covers. And your car is ready to go.

Hopefully, now you know what to do with the broken transmission line.


A little more information regarding the transmission cooler line may come in handy. So we invite you to take a look at our faq section.

How long does the repair take for transmission cooling lines?

The transmission cooling line is one of the inner parts of the engine. To completely repair and test the outcome you’d have to wait at least 1-2 days. Mechanics will see where the problem is then repair it and test it. The timing for it may take less or more depending on the complexity of the issue.

How much does it cost to replace transmission cooling lines?

The repair cost for the transmission cooling line ranges from $100 to $500. The price of the house isn’t much. What costs more is the labour value. The labour value will vary depending on mechanics to mechanics. It also depends on the complexity of the transmission line’s position.

Why does the transmission cooler line break go bad?

Transmission cooler lines can go bad due to high temperature and road debris. Sometimes this causes crack on the connection line and makes the fluid leak out. Another reason could be the torque pump of the vehicle. If it gets damaged the transmission line might also go bad.

Final Words

To summarise, that’s all your options if the transmission cooler line broke while driving

Don’t forget to do a proper check-up on your car engine and transmission cooling. Because a long-term solution is the best policy.

Wrapping up for today. See you next time!

Robert Lozano

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