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A transmission fluid leak is among the most dangerous leaks in a car as it directly threatens our lives. Thus, early root problem detection and immediate fixes are required whenever you notice this red fluid leaking from car. However, only some know the possible causes and what to do when a leak arises. 

Worry not; today, Driverevole gets your back with the 7 most common causes of a transmission leak and the best fixes!   

What Happens If You Have A Transmission Fluid Leak?

Lack of transmission fluid leads your gearbox to overheat, wear out prematurely, and ultimately break. Additionally, depending on the scope of the problem, this can lead to pricey fixes, rebuilds, or component changes.

If you have a transmission fluid leak when parked, the fluid puddle might induce fires and burn nearby objects, leading to catastrophic events. The worst case is that you’re in the car when it burns.
Transmission fluid leakage is extremely dangerous. – Car Treatments 

Furthermore, transmission fluid is highly combustible and under pressure in certain sections of the mechanism. Thus, if it drips onto the tailpipe, it might spark flames and burn the rubber pipe coupling with your transmission fluid coolers (which also explains the car’s burning rubber smell). Consequently, this hot, spraying transmission fluid might burn your car quickly. 

If you have a transmission fluid leak when parked, the fluid puddle might induce fires and burn nearby objects, leading to catastrophic events. The worst case is that you’re in the car when it burns.

Transmission Fluid: 7 Causes For The Red Fluid Leaking From Car 

When you notice red fluid leaking from your car, the first and most common possibility is a transmission fluid leak (although some other liquids share the same transmission fluid leak color). 

Finding out the root problem of the leak will help you save money on unnecessary repairs and replacements. Below are the 7 most common reasons behind a transmission fluid leak.

Seals

The gearbox in your car uses a set of gaskets, which are usually rubber.

The gearbox in your car uses a set of gaskets, some of which are metal and the others are usually rubber.
Transmission seals might be the leak’s cause. – Pep Boys

 Beneath the hood of your car, temperatures often range from 195°F to 220°F, causing these gaskets to degrade faster. And as these gaskets deteriorate, particularly the pan seals, they become crumbly and bleed transmission fluid.

Torque Converter Leakage

A torque converter is responsible for pumping transmission fluid all over the gearbox. Transmission fluid may escape from these torque pumps if there is a fracture in its casing or the needle bearings are defective.
Your torque converter might be to blame. – Auto Guide

A torque converter is responsible for pumping transmission fluid all over the gearbox. Transmission fluid may escape from these torque pumps if there is a fracture in its casing or the needle bearings are defective.

Pipes

Similar to how brake fluid flows through the brake pipes to the brakes, transmission fluid runs along tubes to different gearbox parts. Aluminum or steel is usually the material of these lines.

Similar to how brake fluid flows through the brake pipes to the brakes, transmission fluid runs along tubes to different gearbox parts. Aluminum or steel is usually the material of these lines.
Check your pipes for cracks and holes. – V&F Auto

 Such lines are made to withstand the test of time and are sturdy, but they may break over time and under high temperatures. Once that happens, you can predict the outcome. Instead of circulating inside the gearbox, transmission fluid will seep outside.

Clogged Transmission Ventilation

A common feature of automatic gearboxes is an uncovered transmission valve located on the top of the gearbox to prevent the unit from being over-pressurized. A few vehicle models have tiny gearbox vents that might be congested, causing transmission fluid to drip all over the place.

Check the top of your gearbox for venting valves, or consult your manufacturer for more information. Due to their location atop the transmission, these vents can be tricky to access.
If you have blocked vents, transmission fluid leakage might happen. – Corvette Forum 

Check the top of your gearbox for venting valves, or consult your manufacturer for more information. Due to their location atop the transmission, these vents can be tricky to access.

Pumps 

Your transmission pumps push transmission fluid along the gearbox’s pipes. And a transmission fluid leak may occur inside these pumps. 

Pumps 
Your pumps might be the culprit. – RX Mechanic 

Indeed, in most cases, your transmission fluid escapes or gets shoved out of the pumps as it runs into the unit due to a hole in the pumps’ housing.

Pans And Plugs

There will inevitably be considerable depreciation on your gearbox pans after a good while. Since the pans of your gearbox usually sit close to the floor, they are vulnerable to damage from pebbles and other roadway particles.

A leak can happen if the pan is punctured or the drainage valves (or bolts) aren’t securely in place. 

If something heavy like a boulder punctured the pans, your gearbox would immediately begin to leak fluid. If this occurs, you may notice it immediately due to strange behaviors. In contrast, a minor tear or rupture will go undetected for some time

Pans And Plugs
Examine your gearbox’s pans and plugs. – Reddit

Leaks can also be caused by a drainage valve or bolt that has not been appropriately fastened (or that has been twisted to the brink of stripping). This is a common problem just after transmission fluid maintenance.

Installation

Last but not least, your gearbox installation is a big task, and fluid leakage may develop if you don’t do the job correctly. As a result of improper fitting, your transmission pans are the most common source of leaks.

Either you use the wrong bolts to fasten the pans or install them improperly is why your transmission fluid is leaking. 

How To Locate The Leak’s Source 

Oftentimes, the culprit of a gearbox leak is perplexing. The best technique to find the source of a leak is to eliminate all possible probabilities.

The most effective way to achieve this is to use a degreaser or brake cleaning solution to deep clean the underside of your automobile. You need to remove all grime and debris from the motor, gearbox, frames, and floorboards.

After cleaning the underside, you can take your vehicle for a short ride and then rest it on a carton board. Check your gearbox and parts with a powerful LED flashlight if the leak persists.

How To Locate The Leak’s Source 
Detect the leak’s source using a LED flashlight. – Your Mechanic 

If you’re still having trouble pinpointing the source of the gearbox leakage, a leak detection tool for automobiles could help. These sets often include a UV laser, colored eyeglasses, and a tube of petroleum-based fluorescent pigment.

Add the specified amount of pigment to the transmission fluid and run the car for the required time to ensure the gearbox starts leaking. Afterward, you can utilize your UV laser and eyeglasses to pinpoint the leak’s location.

6 Best Fixes For A Transmission Fluid Leak 

Professional gearbox repair is often necessary. However, if you are confident in your mechanical expertise, you may conduct a few fixes on your leaky gearbox in the comfort of your own house or yard. 

However, whether or not you feel confident enough to tackle gearbox fixes on your own, the first step is always to assess the extent of the damage. It just requires a couple of ATF drops to create a puddle the size of a dish.

Depending on the severity of your gearbox’s damage, you can fill up your transmission fluid (do not overfill transmission fluid) and go (slowly and cautiously) to the service center. If your ATF puddle resembles a tiny red pond, you should call a tow service.

Here are the most common repairs for a transmission fluid leak:

Replace Fluid Lines

You’ll want a rubber gasket that can tolerate extreme temperatures and pressures as transmission fluid gets pumped at a very rapid rate of speed. Leaky gearbox pipes should have the whole line replaced.

Replace Fluid Lines
Replace your fluid pipes when you notice any crack or hole. – Rick’s Free Auto Repair Advice

Splicing in a fresh part of the pipe is possible (on a low-pressure return system), but coupling clips and a short piece of piping only last for a while.

If your issue is emerging from a pressurized cooler pipe (the type that has metal tips), you must replace the whole section. To avoid leaks, you must ensure that the o-rings are well installed before you tighten the bolts. Or else you’ll have another spill.

Change The Gaskets

Replacing the gaskets inside your gearbox pan is a simple way to stop leaks. If you have already discharged the liquid and taken out the pan, all that remains is to detach your old gaskets, scrub the area thoroughly, and put in the replacement gasket. While you’re at it, replace the transmission filtration system as well.

Replace The Pan

Broken transmission pans require immediate replacement. New ones are available for order at auto-parts retailers and car dealerships.

But if you go to a scrap yard, you can pick up a refurbished one for a few bucks less. Simply unbolt the broken one and screw in the replacement piece (a fresh pan seal is necessary, of course).
Installing a replacement pan is also advisable. – Blue Devil Products 

But if you go to a scrap yard, you can pick up a refurbished one for a few bucks less. Simply unbolt the broken one and screw in the replacement piece (a fresh pan seal is necessary, of course).

Install New Seals

Replacing your broken gearbox seals is a simple procedure. Having identified the defective seal, you need only remove it, then replace it with a brand-new one.

You must ensure that you install the replacement seal properly. Otherwise, you’ll have to start from scratch and repair the issue repeatedly.

Install New Drain Plugs Or Pan Bolts

Perhaps the teeth on the screw are old, and the rough road’s impact finally loosens your plugs, causing the leak. Try tightening a replacement bolt into place, taking care not to shatter your gaskets in the process, and you’ll soon figure out whether it’s the root problem.

If the issue persists after the repairs, try changing the gearbox bolts or adjusting the driveshaft position.

Change The Torque Converter 

This is rare, but a transmission fluid leak might happen if you have a cracked or damaged torque converter. In this case, the only option is to change the faulty device. Since the process requires expertise (and the location is pretty hard to reach), it’s advisable to ask for professional help.

Wrapping Up 

The red fluid leaking from car might be more dangerous than you think! Indeed, in the worst case, a transmission fluid leak might even cause fire, threatening your safety. Thus, whenever you notice signs of transmission fluid problems (for example, strange transmission fluid colors) or a leak.

For more content like this, check out our Fun Driving section.

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