A transmission fluid leak can be caused by many things. It is important to diagnose the problem before you attempt any repairs.
If your transmission fluid has leaked onto the ground, it will have left a reddish puddle beneath your vehicle. The color of the leak should give you an idea of what type of leak it is and how bad it is.
Transmission fluid leaks when parked may be caused by a number of issues including worn seals or gaskets, a bad torque converter seal, or leaky hose clamps. In this article, we will cover the common causes, signs, and fixes of transmission fluid leaks.
Table of Contents
What are the causes of a transmission fluid leak?
Below, we will outline the most common causes of transmission leaks when your car is parked.
One of the most common causes of a transmission fluid leak when parked is a broken seal or leaky pan gasket.
Broken seals
Transmission fluid leaks are a common issue with cars and often happen when the car is parked. Transmissions contain several seals to help prevent these leaks, but over time they will deteriorate and be more likely to develop cracks that lead to a leak.
Broken seals may be caused by age or wear and tear on parts, over time leaking fluids will get through the seal and the leak will start to show.
Generally, transmission fluid leaks occur when the seals are bad. This may be attributed to other problems elsewhere in the car. It can be a difficult problem to diagnose without thorough troubleshooting of the issue because it is often hard to determine where they will leak from prior to actually occurring.
Damaged transmission pan
If your transmission fluid is leaking when you park, it could be because of a damaged transmission pan. Transmission pans are designed to catch the majority of fluids that leak from the car’s engine and they often have small holes in them for this purpose.
Pan damage may be caused by age or wear and tear on parts as well as incidents where the transmission fluid is at a high temperature and leaks through the pan onto the ground.
The transmission leak will occur when there are holes in the pan that allow fluids to escape or where it has worn away completely.
Damaged transmission fluid lines
One of the most common causes of leakage from your car, while parked, is faulty transmission fluid lines. Leaking transmission fluid lines may be caused by the absence of a protective coating on the line. This is often found at threaded joint connections and can cause small drips when parked in addition to larger leaks from an exposed tube once it’s been sitting for a while.
As you drive, transmission fluid lines are adversely affected by debris on the road. They may also be damaged as a result of heat or cold and they can wear out over time. When this happens, transmission fluids will naturally leak.
Transmission overheating
Transmission fluid leaks when parked are often a sign of overheating. Your transmission includes several seals to prevent leaking and many of these will fail if the car is running for too long at high speeds or with heavy acceleration, especially in hot weather.
When your transmission fluid starts to overheat, it may need additional attention such as new seals or a transmission fluid flush. To prevent this problem from happening, you need to ensure your transmission has enough transmission fluid at all times.
Damaged transmission pan gasket
Leaking transmission fluid when parked may be due to a damaged transmission pan gasket. A pan gasket is designed to seal the transmission and keep fluids in, but over time they will deteriorate or have holes poked through them by debris on the ground which can cause leaks while your car is idle.
Although it’s just a small part, the transmission fluid seal is fundamentally important to your car’s transmission system. If your seal tears or rots prematurely, you may start running low on transmission fluid and experience leaks.
Transmission gears slipping
Transmission fluid acts as an intermediary between the vehicle engine and rear-wheel axle. Transmission fluid is typically required to ensure fluid driveline torque at all times, but owners should always maintain a perfect balance of these components by ensuring the transmission fluid level doesn’t drop too low.
If the transmission fluid level gets too low, your car will experience slipping of gears because of the lack of hydraulic pressure. This condition will also cause the transmission fluid to leak out of the pan.
Some car transmissions have gears that slip when they are exposed to high heat. When this happens, the transmission fluid may leak out of these areas where there is a seal located between two pieces of metal.
Commonly, slippage occurs in the front and rear differential gearboxes as well as certain types of clutches which can cause leaking after prolonged periods of use.
Not changing fluid often enough
Over time, transmission fluid begins to break down and can cause the seals in your transmission system to wear more quickly. If you are too late in changing your fluids, they may start leaking when parked because of this deterioration process.
The general best practices for maintaining a healthy car include routine maintenance such as an oil change every three months or so depending on your driving habits. If you are overdue on a routine maintenance, it is possible that the leaking transmission fluid may be related to other problems with your car.
Delayed gear engagement
The transmission gears of your car have to build up a certain level of pressure before it can start moving. If the fluid is too low, then there will be a time lag in between shifting gears.
This delayed movement causes the transmission fluid to leak from the pan. When you apply more pressure on the gears, more transmission fluid will leak. This can damage your car’s brake system and also waste some of the expensive fluid. To prevent this problem, regularly change your transmission fluid depending on your vehicle’s recommendations in order to prolong its lifespan.
Torque converter
The transmission gears of your car have to build up a certain level of pressure before it can start moving. If the fluid is too low, then there will be a time lag in between shifting gears.
This delayed movement causes the transmission fluid to leak from the pan. When you apply more pressure on the gears, more transmission fluid will leak. This can damage your car’s brake system and also waste some of the expensive fluid. To prevent this problem, regularly change your transmission fluid depending on your vehicle’s recommendations in order to prolong its lifespan.
Transmission gaps
Transmission fluid leakage may be caused by gaps in your transmission system. When the engine is not running or if your vehicle has been idling for a long time, there will usually be some type of pressure release from these areas.
If this occurs and you are low on transmission fluid, then it is possible that the seal may have failed or the seal might be broken. In either case, you’ll need to get your car’s transmission fluid level checked before driving again.
Car accidents
If you’ve recently been in a car accident, there is the possibility that your transmission fluid could be leaking from somewhere. The fluid may leak from between two metal parts or be forced out of seals at high speeds and pressure.
Additionally, if your vehicle was involved in a collision, it might cause leaks where the rubber gaskets are located.
If this is the case, you’ll need to take your car to a mechanic for an inspection before driving again.
Symptoms of leaking transmission fluid
Transmission leaks can be difficult to pinpoint because they often manifest in different ways. You may notice that you have a leak if your car develops any of the following symptoms:
Car accelerates slowly
Transmission fluid is necessary to lubricate the gears of your car’s transmission. If you notice that your car is accelerating slowly or if it feels like you’re pushing the gas pedal as far as possible, then this could be due to a leak in the system.
Gears are grinding
If gears are grinding, then there could be a problem with the transmission fluid. Leaks in this area will prevent them from shifting properly or they may start to grind together if you are driving your car when it has a low level of transmission fluid.
Gears slipping
Another symptom that is indicative of leaking transmission fluid is if your car’s gears slip when you’re driving. This can be caused by a leak in the transmission pan or seal, but if it happens often then it could also mean that your car needs to have its fluid levels checked.
Transmission producing excessive heat
An overheating transmission can be indicative of a leak. If you notice that your vehicle is producing an excessive amount of heat or if the engine light has come on, this could indicate a problem with leaking transmissions.
If your car’s radiator fan doesn’t turn off when it should and there’s fluid near it, then there may be something wrong with the fluid level or seal.
If you notice that your transmission is overheating, then take it to a mechanic as soon as possible and have them inspect what’s wrong with the system before driving again.
Puddle beneath your car
When you park your car and there’s a puddle beneath it, then this is often an indicator of transmission fluid leaking. The fluid color you see on the ground depends on what type of transmission fluid is leaking. Typically, transmission fluid is red. However, you may observe a puddle of red, brown, pink, or green fluid.
Transmission fluid is often used to lubricate other internal car parts like the vehicle’s steering. Therefore, it may not necessarily come from the transmission when parked.
If you notice that there’s a puddle below the car and it is not red, then this may be indicative of another internal issue.
Vibrations
If you notice that your car is vibrating more than it should, then this could be a sign of transmission fluid leaking.
This may happen when there’s an issue with the seal or if the rubber gasket has failed. This can also occur due to leaks in other areas of the vehicle like in brake lines and fuel tanks which cause vibrations or the vehicle feeling like it’s not running smoothly. If you feel weird vibrations when you’re driving your car it’s usually not a good sign and you should bring it to a mechanic ASAP.
Preventing transmission fluid leaks
The longer you put off fixing transmission fluid leaks, the more expensive the repairs will be. By taking precautionary measures, you can help ensure that your transmission doesn’t leak. Here are some tips on preventing transmission fluid leaks:
Regularly check fluid level
The first step to preventing a transmission fluid leak is ensuring that your car’s fluids are at the right levels. If you feel like something isn’t quite right, then make sure you check for low transmission fluid levels before driving again. This will help avoid leaks as well as other expensive issues with the vehicle. Your vehicle should have a transmission dip stick to check for the levels.
Change transmission fluid regularly
Changing your transmission fluid at the right intervals can help prevent future leaks. It’s important to do this regularly in order to avoid a leak and keep all other parts of the vehicle running smoothly. You should check your owner’s manual as well as any warning lights on your dashboard when looking for information about how often you need to change your car’s transmission fluid.
Drive properly
When you’re driving, avoid sudden starts and stops. These will put more pressure on your car’s transmission which can lead to a leak if there is an issue with the seal or gasket. Driving smoothly and waiting until you stop before shifting gears will help to improve the longevity of your transmission.
Fixes for car transmission fluid leak
Before you begin, you need to make sure that the leak is coming from your transmission. The fluid color you see on the ground depends on what type of transmission fluid is leaking. Typically, it is red and thinner than motor oil but can be a reddish-brown, pink, or green depending upon the make and model of your car. It’s important to take time to identify that this leak has originated in your transmission before making any expensive changes or repairs.
Find the source of the leak
The fluid can also leak from other parts of your vehicle like the brake lines or fuel tank. So, if you notice a puddle and it’s not red then this may be indicative of another internal issue that needs to be addressed.
Determine if the problem can be fixed
Once you determine the cause, you will need to find out you’re able to fix it yourself or if you’ll need to bring it to a mechanic. A few drops of fluid leak can sometimes be considered as a smaller nuisance while a puddle of fluid is a larger problem that would require an expert diagnosis and a more difficult solution. Its consequences could also be dangerous if left untreated and could lead to more expensive repairs.
Find what you need for repairs
Tools and materials that you will need for the repairs depend on what caused the leak in your transmission fluid. A lot of these parts are available online. Here is a list of common materials you may need:
- Jack stands or ramps
- Transmission fluid
- A good funnel
- New transmission pan
- New transmission pan bolts and drain plug
- New seals
- New gaskets
- New cooler lines
- Hose clamps
- Catch pan with drain funnel
- Transmission fix of the renowned brand
Drain the transmission fluid
The next step is to drain the transmission fluid. You can do this by removing the drain plug from the transmission pan and then using a catch basin. Make sure you are wearing appropriate safety gear such as gloves, glasses, protective clothing, or goggles when dealing with a leaky fluid.
Fixing the problem
There are different solutions depending on the problem you need to fix:
Tightening or replacing bolts or drain plugs: If you have a leaky bolt or drain plug, then tightening it may be enough to stop the leak. You can tighten bolts with an adjustable wrench or pliers and replace them if they are too old.
Replacing gaskets: If the transmission fluid leak is coming from a gasket, then you need to replace it. Make sure you remove all traces of old sealant or grease before replacing your transmission pan’s gaskets. When draining the fluid, you’ll need to remove its pan by removing its bolts. You’ll see a lining gasket over the pan. Replace the gasket with a new one and apply some oil to grease it in place. Re-install pan and tighten bolts.
If you have any other problems then it’s recommended you take your vehicle to a mechanic.
Refill the transmission fluid
Once you’ve drained the transmission fluid and solved the problem, it’s time to refill it. Make sure that your car is on a level surface before you begin and use safety gear when handling this process.
Pour in about two quarts of clean transmission fluid into the pan and then replace its drain plug with a new one (make sure it is compatible with the make and model of your vehicle).
When you’re ready to install the transmission fluid, make sure that all old gaskets have been removed from the pan. Replace them (if necessary) with new ones before inserting its bolts into place. Tighten them firmly and then you’re done!
FAQs
What's the cost of fixing a transmission fluid leak?
A leak in your transmission fluid can be fixed by replacing its gasket, if the cost of a new pan is too expensive. The average cost for this repair ranges from $150 to $250 depending on the make and model of your vehicle. If you’re looking for cheaper options, then it’s recommended that you do some research before making a decision.
How serious is a transmission fluid leak?
Transmission leaks are not serious at first but the longer they go untreated the more damage they cause. They can lead to a number of other problems such as breaking down, slipping gears, or your car not starting.
Can you drive if your car is leaking transmission fluid?
The leaking is an issue as the liquid inside of it is highly flammable. If not taken care of, you could find yourself with decreased acceleration and other serious issues occurring. So while small leaks are ok to drive on, if a leak becomes large enough you should take the car to an auto repair shop.
If you notice a transmission fluid leak after having flushed the car, go back to the expert and get it fixed. The faster you act, the less damage will be done to your car.
