What Happens if you pour too much Transmission Fluid?

It is essential to maintain an adequate level of transmission fluid at all times to avoid causing catastrophic damages to your transmission. You should pay attention to noise coming from under the hood. That is, any type of noise that could indicate transmission issues. One of such noises that signify problems in the transmission is screeching noise.

If your transmission fluid is low, it will start making noise. On the other hand, overfilled transmission fluid has its advert effects. It is important not to add too little or too much transmission fluid.

This article explains various types of transmission systems, how they work, and highlights overfilled transmission fluid effects. Let’s delve in.

How does a transmission work?

The car transmission is one of the essential components of a vehicle. It transfers power from the engine to the wheels, enabling the car to move. It comes in various forms. There are automatic and manual transmissions. The manual variant requires the driver to perform extra tasks to move effectively.

Have you ever wondered ‘what does a transmission do and how does it work?’ Its functions and applications vary depending on the type of transmission you own. Regardless of the transmission type, it enables the wheels to move accordingly as the vehicle speeds up or slows down.

When a car comes to a stop, the transmission disengages the drive shafts from the engine so the vehicle engine can idle when not in motion. The transmission also works in harmony with the engine to enable fast movement of the vehicle as you step on the gas pedal.

Let’s explore the various types of transmissions below;

Manual transmission

transmission fluid change

Manual transmission requires the driver to perform an extra task using the clutch pedal and a gear lever or shifter for the vehicle to run effectively.

These transmissions are designed with a pair of input and output shafts and a set of gears. The effective running of the manual transmission depends on the driver as he has to select proper gears to engage or disengage the clutch system.

The manual transmission utilizes a clutch moon, pressure plate, and flexplate to engage and disengage the driveshaft from the engine.  The pressure plate and the flywheel (flexplate) are mounted at the back of the engine. The clutch moon is installed on the center axis of the flexplate and is splined on the transmission input shaft.

Automatic transmission

What is the automatic transmission? The primary difference between automatic and manual transmission is that manual variant requires an extra task for it to function properly. In contrast, in an automatic transmission, the system determines when to up-shift or downshift the gears. The automatic transmission doesn’t use pressure plates and clutches; instead, it uses a torque converter in shifting gears.

The most common automatic transmission uses hydraulic pressure in shifting gears. It combines a fluid coupling or torque converter and gear sets to up-shift and down-shift into different gear ranges as you step on the accelerator pedal.

The fluid coupling connects the transmission to the engine and uses pressurized fluid to shift the gears. The fluid coupling replaces the friction clutch in manual transmission and can halt the car to a complete stop without stalling.

CVT Transmission

The acronym CVT, which stands for continuously variable transmission, is pulley-controlled transmission mostly seen in small passenger cars with small engines. CVTs have been featured in most ATVs, snow machines, and side-by-sides, amongst others. They are primarily installed in small hybrid vehicles.

CVT transmissions have a basic setup of a second large and primary small driven clutch, with a chain or belt that connects both clutches. The chain or belt will sit high in the secondary drive and low in the primary drive when not in motion.

As you step on the gas pedal, the secondary drive will expand, causing the chain or belt to walk down, and at the same time, the primary drive will contract, causing the chain or belt to walk up.

What happens if you add too much transmission fluid?

Too much transmission fluid causes serious effects that can cost you hundreds of dollars. We’ve listed the effects of overfilling your transmission fluid below.

Erratic shifting: If you pour excess fluid into your transmission, the gear sets and bearings will be submerged in the fluid. And as a result, the gears will find it challenging to shift appropriately. In other words, too much transmission fluid causes slipping of gear teeth.

Foaming Fluid: Overfilled transmission fluid will cause foaming. Once the foaming occurs, it’ll lead to several transmission issues such as inadequate lubrication, overheating, hard shifting, etc. Over time, it could damage the entire system beyond repair.

Oil starvation: Depending on the transmission size, having a 4-5 liters transmission overfilled by 1 quart will cause foaming. Extra 1 quart might not have a negative effect on 8lrs transmission. Suppose foaming occurs, the gears will start sticking. They won’t function properly because the oil has lost its density and viscosity. This could lead to catastrophic damages within the transmission assembly.

Lack of lubrication: Since overfilled transmission fluid will cause foaming, it will not lubricate the transmission parts properly. This will result in system wear and tear and could lead to a total breakdown in the long run.

Transmission overheating: If you overfill your transmission fluid, the transmission will overheat. Too much transmission fluid will not allow adequate air to cool down the system. However, half a quart too much transmission won’t make any difference

Transmission fluid leakage: Excess transmission fluid will cause high pressure in the system. When this happens, the fluid will start looking for means to escape and could end up leaking fluid from every possible means. This will cause damages to other system components.

As stated above, automatic transmission relay on pressurized fluid from the torque converter to function. If you overfill it, the transmission will experience hard shifting and slippage.

Another consequence of overfilling your transmission is that it will cause the fluid to lose its lubricating properties. It could also lead to the entire system blowing up and not functioning. If this happens, you’ll be left with an expensive repair bill.

In any case, having your transmission fluid overfilled a little, about half a quart, will not cause issues to the transmission.

The Dangers Of Adding Too Much Transmission Fluid YouTube

FAQS

Q: How do you remove excess transmission fluid?

The simplest means of removing excess transmission fluid involves taking your car to a service garage or draining the fluid yourself. You can drain the fluid by removing the crankcase plug or applying a filler tuber.

If you choose to go with filler tuber, you’ll need to invest your time in it. You will have to hold the filler tube until the fluid reaches the cap, then pull it out and drain it into a catch pan.

Q: Can too much transmission fluid cause the transmission to slip?

Excess transmission fluid can cause several adverse effects to the transmission. If the fluid stays above the recommended level, it can cause it to start mixing with air. This can lead to gear slippage, hard shifting, and other transmission shifting issues.

Q: Will an overfilled transmission leak?

Overfilled transmission fluid might not damage your transmission seals, but it will cause them to leak. The transmission is designed so that pressure won’t leak in unpressurized areas. If a high pressure occurs due to excess fluid, it will leak through the seals.

Q: Why does my car jerk when shifting gears with automatic transmission?

Several factors could cause your automatic transmission to jerk when shifting gears. However, here are common causes that you should watch out for; if you feel jerky, shaky, or hard shifting, it could mean you need to change your transmission fluid or the fluid level is low.

Q: What do I do if I put too much transmission fluid in my car?

Once you notice you have too much transmission fluid in your car, you need to act fast to avoid letting it cause severe damages to the system components. You can either take your vehicle to a service garage or reduce the fluid yourself. You also have to keep the fluid at the recommended level.

Q: Can too much transmission cause limp mode?

When internal transmission or engine sensors detect issues with the transmission, it will place the car in a limp mode. So, you can drive safely to a dealership or mechanic garage for a repair. And if you continue driving your state in this state, it will cause catastrophic damages, and you don’t want that to happen.

Final words:

The proper functionality of every transmission relies on the fluid, as it is the lifeblood of the transmission. Adding too little fluid to your transmission will expose it to premature wear and tear.

On the other hand, adding too much transmission fluid can cause severe system damages. If this happens, it will lead to an expensive repair. Once you notice any of the above signs or effects, fix it immediately before it escalates.

Osuagwu Solomon

Osuagwu Solomon is a seasoned automotive technician for the past 9 years, and a technical writer. He loves writing about auto professional repair guides, DIY repair guides, and buyer’s guide. After spending six years in the automotive workshop, he decided to impact his knowledge to people aside his domain, and he has achieved this by centering his Automotive writing skills on REPAIRS.

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