Can Too Much Transmission Fluid Cause Overheating?

Filling the transmission system with too much fluid is dangerous to both the engine and the internal components of the engine. People do not know that when there is excess fluid in the transmission, it foams up and loses its quality.

The implication of this includes gearing issues, damaged transmission, and oil starvation. When the oil loses its quality and foams, it cannot perform hydraulic and lubrication functions.

Furthermore, the transmission is overworked, causing more engine heat and subsequent damage. This article will examine the implication of too much transmission fluid, whether it can cause overheating, and other related topics.

too much transmission fluid

Can too much transmission fluid cause overheating?

Too much transmission fluid places much pressure on the transmission system, which could result in overheating. When the transmission fluid goes beyond the recommended or even if the transmission overfilled by 1 quart, the level of work done by the transmission system and engine increases, causing overheating.

There is a reason why there is a recommended level of filling the transmission reservoir given by the manufacturer. Manufacturers have run many tests to obtain the optimum transmission fluid level with which the system and engine can work.

When you have an overfilled transmission fluid that goes beyond the recommendation, it does not just affect the transmission system but also the engine.

First, extra pressure is created within the transmission system when you overfill transmission fluid. It makes it more difficult for the system to perform its basic function. For instance, there is an increase in pressure, causing gear shift issues, and damage to internal parts, fluid leaks, and more.

We must note that the engine powers the transmission system. Once the pressure increases in the transmission system, it directly affects the engine. Now, the workload of the engine increases. When there is too much pressure, it takes more power for the engine to power the transmission system.

Once the engine workload increases, it is easier to overheat. The more the engine works, the more heat it generates.

You would expect that the engine cooling system would be able to handle excess heat generated by the engine, but it is not always so. When there is an overfilled transmission, the transmission system generates a lot of heat, contributing to the engine’s heat.

The transmission fluid performs a lubricative function for parts of the transmission system. When there is a “transmission overfilled” problem, lubrication of the transmission part is prohibited. The air easily mixes with the high fluid level, causing a foamy reaction contaminating the fluid.

In addition, with less lubrication in the transmission system, a lot of heat will be generated, which will be easily transferred to the engine, causing overheating. Thus, learn the transmission fluid cooling.

Symptoms of overfilled transmission fluid

Overfilling transmission fluid comes with many issues affecting the engine and transmission components. You will likely experience problems with changing the gear, leaks, and other transmission issues.

Below are some of the symptoms of overfilled transmission.

1. Trouble changing gears

One of the first overfilled transmission symptoms you will notice is a problem with shifting the gear. When there is too much transmission fluid in the system, it causes the fluid to foam. It allows the gears to compress. The foam begins to implode inside the gear. When this happens, you get a shifting problem coupled with other issues.

2. Strange noise from the transmission system

Other overfilled transmission fluid symptoms are grinding or screeching noises coming from the transmission. It could happen when the vehicle is picking up speed or trying to shift gears.

The noise comes up due to parts of the transmission system grinding together due to the lack of lubrication caused by the overfilled transmission reservoir.

3. Engine overheating

A major symptom of too much transmission fluid includes engine overheating. When the transmission fluid is too much in the system, excess pressure is built, which causes the transmission system and the engine to create so much heat-generating engine overheating.

4. Slipping gears

Will too much transmission fluid make it slip? The answer is yes; your gear is most likely because of the extra pressure on the transmission system. When there is pressure in the system, the fluid begins to foam, which immediately reduces the quality of the fluid, dropping its lubricative ability. All these affect the transmission system’s internal parts, reducing its ability to maintain gear.

5. Transmission leak

When there is too much transmission fluid, it becomes aerated and foamy, causing a lot of pressure. Once the pressure builds up to a certain level, parts of the transmission system, like seals, wear off faster.

Once parts start to wear off, spaces are created for the fluid to slip out. Once there is excess oil, the transmission fluid leaks through a damaged part, and the best option is through the seals.

6. Slow acceleration

Overfilled automatic transmission fluid symptoms include slow acceleration. The fluid will lose its quality once, affecting the transmission system’s internal components. In this case, the vehicle will be slow to pick up acceleration or change gear due to the affected transmission parts.

7. Burning smell

Excess fluid in the transmission system will cause the transmission and the engine to overheat. Once this happens, the fluid will heat, causing part of it to get burnt by the heat. The smell of the brunt fluid could find its way to the vehicle’s interior through the AC vent.

Above is what happens if you overfill transmission fluid, which should be treated urgently. Once too much transmission fluid symptoms are ignored, you will face a failed transmission that costs even more to fix.

How much transmission fluid means too much?

There is a recommended transmission fluid filling for every vehicle because of varied fluid filling extents. However, checking the dipstick lets you know if the fluid is too much. It is too much if the fluid goes beyond the recommended extent or if there is an additional one or more quarts.

Before filling the transmission fluid, we advise you to check the owner’s to understand the manufacturer’s recommendation. You could also contact a professional to get the proper recommendations.

How do you remove excess transmission fluid?

Removing Excess Transmission Fluid YouTube

Once you realize that the transmission fluid is too much, the next step is to remove the excess fluid. You can do this by sucking the fluid using a hand-operated vacuum through the transmission fluid pump. The drain plug is a good way to let out the fluid; if you have used it in that condition for a while, it is now contaminated.

Below are steps to remove excess transmission fluid.

1. Park your vehicle in a safe space and then proceed to lift the car. You might not need to raise the vehicle if it is a truck.

2. Locate the drain plug, usually at the bottom of the transmission housing, for manual transmission and the transmission pan for automatic transmission.

3. Once the plug is found, place the drain pan under the plug and unplug it to drain

4. Allow the fluid to drain completely, then fix the plug.

5. Accurately fill the vehicle with transmission fluid according to the manufacturer’s recommendation.


Too much transmission fluid in the system will eventually lead to failure, the final symptom of overfilled CVT transmission. You must consider how much transmission fluid you pour into the system. If you are unsure of how much transmission fluid your vehicle requires, you could seek professional help. They will not just help with filling the transmission fluid, but you will also receive great advice and recommendations for next time.

Akindayini Temiloluwa

I am Akindayini Temiloluwa, an automotive expert writer and car enthusiast. I have over three years of experience in the automotive writing niche and have completed over 300 pieces of content from 50 projects. I have vast knowledge and skill in vehicle repairing, all mechanical work, car upgrades and maintenance. My goal as an automotive content writer is to simplify the most challenging concepts for my readers, help them self-diagnose what may be wrong with their vehicles and offer real value for their time.

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