Transmission Fluid Leak Symptoms, Causes (& Replacement Cost 2022)

Engine oil and Transmission fluid are essential fluids needed for optimum functionality of your vehicle engine system. The transmission fluid is responsible for lubricating mechanical parts, maintaining fluid pressure, cooling, preventing oxidation, conditioning the gasket, and preventing rust. This article explains the causes, symptoms, and replacement cost of transmission fluid leak.

What is Transmission Fluid?

Transmission fluid is a kind of fluid used in a vehicle to lubricate the moving parts of the automatic transmission or self-shifting transmission. It helps make the act of shifting gears less strenuous on your vehicle by lubricating the bearings and moving metal parts within the transmission. 

Transmission fluid is typically colored red or green to distinguish it from motor oil and other fluids in the vehicle.

Transmission Fluid

It is supposed to remain in your vehicle for its entire lifespan without changing it, although many mechanics will tell you (sometimes untruthfully) that you should change this fluid every 50,000 miles, no matter what. Sometimes frequent flushes of the transmission fluid are recommended as well.

Types of Transmission Fluid

There are two major types of transmission fluids:

  1. Automatic transmission fluid
  2. Manual transmission fluid

1) Manual Transmission Fluid

Manual transmission fluid in older vehicles, which is sometimes referred to as manual transmission oil or lube, is common for some older manual transmission cars.

2) Automatic Transmission Fluid

This type of transmission fluid is designed for cars that have automatic transmissions. It’s also used in some more modern manual transmission cars. Automatic transmission fluid meets the requirements of automatic transmissions and helps with various functions, including:

  • Gear lubrication
  • Transmission cooling
  • Torque converter operation
  • Brake band friction
  • Clutch friction operation
  • Valve body operation

Symptoms of Low Transmission Fluid

A sufficient amount of transmission fluids is very important for the efficient working of the transmission system. As the transmission fluid leaks or goes lower than a specific level, it produces one of the below-given symptoms:

  1. Dashboard Warning Light
  2. Slipping Transmission
  3. Delayed Gear Engagement
  4. Overheated Transmission
  5. Irregular Shifting
  6. Inability to Shift
  7. Strange Noises While in Gear
  8. Fluid on Garage Floor

1) Dashboard Warning Light

The dashboard warning light is one of the first symptoms that start illuminating when your transmission fluid level becomes less than a specific level. Many electronic sensors are used in modern transmission systems to warn you about the vehicle problem.

As the PCM of your vehicle detects any fault, it immediately sends a fault code (like P0017, P0012, P0013, P0016, etc.) to the vehicle’s dashboard. If your car’s check engine light is illuminating, it is possible that you have insufficient fluid.

Read More: 54 Car Dashboard Warning Lights

2) Slipping Transmission

The transmission should shift seamlessly without much fanfare. However, if it feels like the gears slip during a change, this is an indicator that the fluid levels might be low. 

Slipping can also be combined with sudden shifting, RPM spikes, and grinding noises. All of these indicate that there is a problem and vital friction materials are unable to engage. If left to continue, significant transmission damage could occur.

Read More: Bad Transmission System Symptoms and Causes

3) Delayed Gear Engagement

As the transmission fluid becomes lower, you are going to notice a delay when shifting occurs. Additionally, when you move the car from Drive to Reverse, there might be a slight pause before engaging. 

This problem occurs because there’s insufficient hydraulic transmission pressure to create the gear change normally.

4) Overheated Transmission

As the transmission fluid decreases, the transmission is left vulnerable due to a lack of lubrication. When the transmission overheats, you might notice smoke coming from the vehicle or a burning smell. 

This problem could also occur with a loss of power and erratic shifting. Either way, you must pull the car over and stop driving before further damage occurs. Otherwise, you are going to need a new transmission. 

5) Irregular Shifting

When shifting does not proceed as it should, it might be due to insufficient fluid. Irregularities might manifest as a smashing feel or a delay.

In such a situation, you may also note that the shifting is becoming more often. Shift timing and smoothness are all impaired due to insufficient fluid supply.  

6) Inability to Shift

If the transmission fluid becomes completely empty, you might not be able to shift the vehicle at all. This sealed system requires lubrication to work. 

You can try and fill the transmission with transmission fluid to see if that resolves the situation. However, driving the car without the right amount of fluid in the first place might have caused irreversible transmission damage. 

7) Strange Noises While in Gear

An efficient working transmission system works completely quietly during driving. However, if you begin to hear rattling sounds or rhythmic hammering while in gear and not in park or neutral, you may have a torque converter problem caused by a lack of fluid.

8) Transmission Fluid on Garage Floor

The transmission fluid on the garage floor is a clear sign of insufficient fluid. You most likely have a transmission leak if you detect a tiny puddle or areas of red or brown fluid beneath your car where your engine and transmission are located.

This leakage is frequently caused by a damaged transmission pan, loose drain plug, or faulty gasket or seal.

Transmission Fluid Leak Causes

1) Clogged Transmission Ventilation

To prevent an excessive pressure buildup within the gearbox, most automatic transmissions include some kind of open transmission ventilation on top of the transmission. Some automobile models may block this little gearbox ventilation, resulting in transmission leaks everywhere.

Clogged Transmission Ventilation

2) Broken Seals

An automatic transmission sustains hydraulic pressure through a variety of transmission seals. However, over time, these seals will crack and get worn out, especially when being exposed to heat often or when you have too much transmission fluid in the system.

transmission fluid leak due to broken seals

If you get a transmission leak from this, there are many areas of the transmission to check. You’ll most commonly find the leaky seal in either the input shaft or output shaft. Otherwise, you should also inspect the transmission pan, driveshaft, plug seals, sensors, shifter housing seal, valve body, tail housing seal, and speedometer input seal.

3) Transmission Fluid Pipe

The fluid lines of transmission are constructed of either steel or aluminum. These lines are usually quite durable, but if they get damaged from road debris or exposed to heat too often, then the lines can crack or even completely break.

Transmission Fluid Pipe

4) Cracked or Rusty Transmission Pan

Another common cause of a leaking transmission is a cracked transmission pan. The transmission pan usually cracks if your transmission has an aluminum transmission pan. 

Cracked or Rusty Transmission Pan

Rust is a problem if you have a steel transmission pan. The pans are thin material-wise, and if they start to rust, rust will create a hole quickly. Check for any signs of rust; if you find any, it is probably time to replace the pan.

5) Torque Converter

A torque converter forces transmission fluid through the transmission system components. This is essentially a torque pump, and it may break and leak fluid over time. The torque converter’s needle bearings are also susceptible to breakage, resulting in transmission fluid leaking.

Torque Converter

6) Bad Transmission Pan Gasket

A leaking fuel pan gasket is the most common cause of a leaking automatic transmission. The gasket should be replaced every time the transmission pan is removed on most car models, but many people install the old one again. This can lead to leaks very soon.

Bad Transmission Pan Gasket

Read More: Causes of Blown Head Gasket

7) Transmission Pan or Drain Plug

Over time, your transmission pan will eventually experience some wear and tear. This is because while driving, the pan of your transmission is susceptible to damage from all the loose rocks and debris on the road.

Damaged Transmission Pan

A leak can occur if the pan gets a small puncture or there are loose drain plugs or bolts. If a big rock or other object were to damage the pan, the transmission would lose fluid quickly. You will know right away when this is happening.

On the other hand, a small hole or puncture will take longer for you to notice. If your drain plug or bolt is not tightened enough (or over-tightened to the point of stripping), it could cause a leak too. Too often, this happens immediately after you change the transmission fluid.

How to Check Transmission Fluid

  1. Turn the engine on for a few minutes before proceeding since the engine should be warmed up to check the level properly. Make sure your car is in the park before getting out and opening the hood.
  2. Find the transmission fluid dipstick. On front-wheel-drive cars, it’s usually located to the right of the oil dipstick. Check your owner’s manual if you’re having trouble finding it.
  3. Remove the dipstick and touch the fluid, moving it around between your thumb and forefinger. The fluid should be nearly clear, with a pink hue. If it looks dirty or gives off a burnt smell, take it to a service center for replacement.
  4. Use a rag to wipe off the dipstick. Then insert it back into the vehicle. Pull it out again and check the level. You’ll need to add more if it’s under the “Full” marking.
  5. Use a funnel to bring the fluid level up to the right spot. Be sure not to overfill it.

Repair Cost of Transmission Fluid Leak

Depending on the vehicle type and labor costs, the typical transmission fluid leak repair costs vary from $75 to $330. You should budget $35 to $180 for components and the rest for labor.

Here are some examples of repairs that could fix a fluid leak cost. The prices include parts, new fluids, and labor work. The prices can differ heavily depending on your transmission model, but it gives you a clue.

Type of workPrice
Transmission Pan Drain Plug Replacement$15 to $60
Transmission Gasket Replacement Cost (Including Fluid & Filter)$130 to $420
Transmission Fluid Line Replacement$35 to $220
Replacement of Transmission Pan (Including Fluid & Filter)$230 to $520

Factors Affecting Transmission Fluid Change Cost

  • Service Center vs. DIY
  • Model of Vehicle
  • Type of ATF
  • Amount of Fluid
  • Cost of Labor for Your Region

FAQ Section

Where is Transmission fluid located?

It is most commonly found near the oil dipstick in front-wheel drive vehicles and near the rear of the engine for rear-wheel-drive engines; it is conveniently labeled for access and can have a red, pink, or yellow-colored handle.

How often do you need to change your transmission fluid?

If your vehicle has a manual transmission system, most manufacturers will recommend changing your transmission fluid every 30,000 to 60,000 miles. If you have automatic transmission fluids, you can typically boost that range up to 60,000 to 100,000 miles. There’s no harm in changing your fluid early.

What is the color of the Transmission fluid?

Most of the transmission fluids are red, but you can get some in blue or yellow. Manufacturers dye them red to distinguish them from other vehicle fluids. As the fluid ages, it changes to light brown, dark brown, and then black. You should consider changing the transmission oil when you note a dark brown color.

What is the Transmission fluid leak?

A transmission leak is a common occurrence that happens through excessive wear over time. The plugs could be loose or the pan could be punctured. Either way, the moment you notice transmission fluid, contact your local mechanic and have them inspect and repair your transmission fluid leak.

How long can you drive with a transmission leak?

Technically, the vehicle can still be driven with low to no transmission fluid for 10 to 15 miles. However, doing so will lead to transmission system failures and can damage the car permanently.

Is it safe to drive a car with a transmission leak?

If your transmission fluid is leaking, it’s not completely unsafe, but it can cause your vehicle to operate improperly. Ignoring a leak for too long could also cause serious, expensive damage to your car.

What happens if you drive with leaking transmission fluid?

If a leak develops in your transmission system, causing you to lose transmission fluid, and you continue driving with low fluid levels, you can permanently damage your car’s transmission leading to costly repairs, rebuilds, or replacements depending on the amount of damage.

What happens if you run out of transmission fluid?

If there is no fluid or hold, the gears cannot spin, and therefore the car won’t be able to move. If your vehicle does get to the point of having no transmission fluid, you will likely also be looking at extensive repairs or even a full replacement of your transmission.

What are the Transmission fluid types?

The transmission fluids have two major types:

  1. Automatic transmission fluid
  2. Manual transmission fluid

What are the signs of transmission fluid leaks?

When the transmission fluid of your vehicle leaks, it gives one of the below-given signs: 

  1. Dashboard Warning Light
  2. Fluid on Garage Floor
  3. Inability to Shift
  4. Slipping Transmission
  5. Delayed Gear Engagement
  6. Strange Noises While in Gear
  7. Overheated Transmission
  8. Irregular Shifting

What causes a transmission to go bad?

Transmission failure can be caused by overheating, lack of fluid due to leaks, symptomatic noises, slipping, or outside factors that affect transmission.

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