Symptoms of Transmission Fluid Leak | How to Change Transmission Fluid?

Transmission fluid and motor oil are vital for the proper operation of your car’s engine system. The motor oil is designed for use in the engine, while the transmission fluid is intended for use in the gear and steering system. The transmission fluid cools the head gasket, maintains fluid pressure, lubricates mechanical components, cools, eliminates oxidation, and prevents rust.

What is Transmission Fluid?

Transmission fluid is a type of lubricant used in a vehicle to lubricate the moving parts of the transmission system. By lubricating the rotating parts of the transmission, it helps make the operation of changing gears on your car easier. This is because the gearbox is located within the vehicle.

The transmission oil or fluid is normally colored red or green so that it may be easily distinguished from other fluids in the car. 

Transmission Fluid

Although many technicians will advise you (sometimes untruthfully) that you should replace this fluid every 50,000 miles regardless of anything, transmission fluid is designed to stay in your car for the whole of its lifecycle without needing to be changed. It is sometimes advised to do frequent transmission fluid flushes.

Types of Transmission Fluid

Transmission fluids have the following two major types:

  1. Manual Transmission Fluid
  2. Automatic Transmission Fluid

1) Manual Transmission Fluid

Manual transmission fluid is often known as manual transmission oil or lube. These fluids are most commonly used in older automobiles with manual transmissions.

2) Automatic Transmission Fluid

The automatic transmission fluids are designed for vehicles with automatic transmissions. Some latest manual transmission vehicles also use automatic transmission fluids. These fluids fulfill the automatic transmission specifications. The automatic transmission fluids use for the following features:

  • Lubrication of gears
  • Cooling of transmissions
  • Brake bands’ friction
  • Torque converter operation
  • Clutch friction operation
  • Valve body proper working

Symptoms of Low Transmission Fluid

As the transmission fluid goes low than a specific level, it gives one of the below-given symptoms:

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

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, P0506, 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: Causes of Check Engine Light Flashing

2) Overheated Transmission

As the amount of transmission fluid drops, the transmission becomes less safe because it doesn’t have enough lubrication. You can smell burning when the transmission gets too hot or see smoke coming from the car.

This issue may also occur with a lack of power and unpredictable shifting. In any case, you should immediately stop driving before severe damage. Otherwise, you’ll need to replace the whole transmission.

3) 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.  

4) Delayed Gear Engagement

A delay in the gear’s engagement is one of the most common symptoms of low transmission fluid. Additionally, while shifting from Drive to Reverse, there may be a little lag before engaging.

This issue develops when insufficient hydraulic transmission pressure produces a regular gear change.

5) Hard Shifting  

If the transmission fluid runs out entirely, you may be unable to shift the car at all. The transmission system requires proper lubrication for efficient working.  

In such a situation, add new transmission fluid to fill the transmission and try to shift the gears. However, running the automobile without the proper quantity of lubrication may have resulted in irreparable transmission damage.

6) 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.

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) Slipping Transmission

The gearbox must move smoothly and quietly without making much of a racket. However, if the gears slide during a shift, it is one of the major symptoms of low transmission fluid.  

Due to insufficient fluid, your transmission system’s gears may also generate grinding sounds and RPM surges.  

Read More: Symptoms of low Power Steering Fluid

Causes of Transmission Fluid Leak 

There are multiple causes of transmission fluid leak, but the following are the major causes:

1) Damaged Transmission Pan or Drain Plug

Your transmission pan will ultimately show signs of wear and tear over time. This is due to the fact that the pan of the transmission is vulnerable to damage when driving due to all of the loose pebbles and debris on the road.

Damaged Transmission Pan

A leak might emerge if the pan is punctured or if the drain plugs or bolts are loose. If a large rock or other item damages the pan, the gearbox will lose fluid fast. When this occurs, you will immediately notice.

A minor hole or puncture, on the other hand, will take longer for you to detect. A leak may also be caused by a drain plug or bolt that is not securely fastened or over-tightened to the point of stripping. All too often, this occurs just after the transmission fluid has been replaced.

2)  Broken Seals

Multiple transmission seals maintain the hydraulic pressure in an automatic transmission. Seals will eventually dry up and shatter under the stress of excessive heat or transmission fluid.

transmission fluid leak due to broken seals

In the event of a leak in the transmission as a result of this, there are several places to look. The input shaft or the output shaft will often have a leaking seal. If that’s not the case, check the speedometer input seal, tail housing seal, tail housing gasket, shifter housing stopper, valve body seal, and valve body casing.

Read More: Pros and Cons of Head Gasket Sealer

3)  Bad Transmission Pan Gasket

A leaky automatic gearbox is the most common reason for a leaking oil pan gasket. On most automobile types, the gasket should be changed every time the transmission pan is removed, but many individuals reuse the old one. This may quickly lead to leakage.

Bad Transmission Pan Gasket

 4) 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. Additionally, the torque converter’s needle bearings are susceptible to breakage, resulting in transmission fluid leaking.

Torque Converter, transmission oil

5) Cracked or Rusty Transmission Pan

A fractured transmission pan is another major cause of a leaky transmission. If your transmission is made of aluminum, you can expect a fractured transmission pan at some point.

Cracked or Rusty Transmission Pan

If you have a steel gearbox pan, rust is an issue. The pans are made of thin material, and rusting will quickly make a hole in them. Check for rust; if you discover any, it’s time to replace the pan.

6) Transmission Fluid Pipe

A transmission’s fluid lines are made of either steel or aluminum. These lines are normally fairly sturdy, but if they are harmed by road debris or overheated, they may fracture or even entirely break.

Transmission Fluid Pipe

7) Clogged Transmission Ventilation

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

Clogged Transmission Ventilation

How to Check Transmission Fluid

  1. The engine must be warmed up to verify the level adequately, so start it for a few minutes before continuing. Before stepping out and opening the hood, make sure your vehicle is in the park.
  2. Locate the dipstick for the transmission fluid. It’s normally to the right of the oil dipstick on front-wheel-drive vehicles. If you can’t locate it, look in your owner’s handbook.
  3. By rubbing the liquid between your thumb and fingers, you may feel the fluid after removing the dipstick. The fluid should be practically clear and pink in color. If it seems unclean or has a burned odor, take it to a repair facility for replacement.
  4. Wipe the dipstick clean with a cloth. Then replace it in the car. Check the level by pulling it out again. You have to add extra if it’s beneath the “Full” mark.
  5. Use a funnel to raise the fluid to the desired level. Make sure you don’t overfill it.

Read More: Causes and Symptoms of bad PCM

Factors Affecting Transmission Fluid Change Cost

  1. DIY vs Service Centre
  2. Vehicle Model
  3. ATF Type
  4. Amount of Fluid
  5. Cost of workers for your region

Transmission Fluid Leak Repair Cost

Depending on the automobile type and labor costs, the typical transmission fluid leak costs vary from $80 to $320. You should budget $40 to $160 for components and the rest for labor.

Here are some examples of how much it may cost to remedy a fluid leak. Parts, fresh fluids, and labor are all included in the costs. The costs vary greatly depending on the transmission type; however, it provides you with an idea.

Type of workCost
Transmission Gasket Replacement Cost (Including Fluid & Filter)$140 to $410
Replacement of Transmission Pan (Including Fluid & Filter)$240 to $510
Transmission Pan Drain Plug Replacement$15 to $60
Transmission Fluid Line Replacement$40 to $210

FAQ Section

Where is Transmission fluid located?

The transmission fluid is readily labeled for access and may have a red, pink, or yellow-colored handle. It is often located near the oil dipstick in front-wheel drive automobiles and towards the back of the engine in rear-wheel drive engines.

What are the symptoms of transmission fluid leak?

Following are the most common symptoms of low transmission fluids:

  1. Illuminating dashboard warning light
  2. Slipping transmission
  3. Strange noises while in gear
  4. Overheated transmission
  5. Irregular shifting
  6. Transmission fluid on the garage floor
  7. Delayed gear engagement
  8. Hard shifting 

How often do you need to change your transmission fluid?

In the case of the manual transmission system, the maximum manufacturers recommend replacing the transmission fluid after every 29,000 to 60,000 miles. In the case of the automatic transmission system, you should change your fluid every 60,000 to 100,000 miles. There’s no harm in changing the fluid early.

What happens if you don't change the transmission fluid?

If your car’s transmission system doesn’t have sufficient or old transmission fluid, then you may face many problems, including gear shifting issues, a decrease in car performance, hard shifting, delayed gear engagement, and a reduction in engine performance.

What is the color of the Transmission fluid?

Most transmission fluids are red, but some are blue or yellow. Manufacturers color it red to distinguish it from other automotive oils. As the fluid ages, it turns light brown, dark brown, and black. As you notice the dark brown color of your transmission oil, you must change it.  

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

It is not recommended to drive a vehicle with leaky transmission fluid. To drive with a leaky fluid is totally unsafe. Therefore, as you observe leaky transmission fluid, you must fix it as soon as possible.

Read More
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  2. Different types of Engines
  3. Working of Engine Valves

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