The Nissan Leaf is one of the most iconic Battery-operated Electric Vehicles (BEVs) in the market. In fact, in 2019, it was the world’s highest-selling electric vehicle before Tesla Model 3 took over the crown in 2020. Originally launched in 2010 in the US and Japan, Nissan revised this car multiple times to get a range of up to 385 km (~240 miles). However, the Nissan Leaf still faced transmission problems from time to time.

The car currently comes in two battery options – a 40KWh and a 62KWh one. The top variant has a max power output of 160 KW compared to the 110 KW of the base model. This also means that the former has higher power consumption and thus, technically a lower mileage. However, the bigger battery does increase the range to 385 km compared to the 270 km for the base variant.

One common thing they share is that both of them are driven by a single motor placed on the front axle (FWD). This motor connects with a transmission before delivering the power to the wheels. First, let’s look at the type of transmission used in the car.

Transmission in Nissan Leaf

Since the Nissan Leaf is a BEV and works with the help of synchronous electric motors, it doesn’t require a traditional gearbox that is seen in most cars with internal combustion engines. This is because electric motors can offer 100% of their torque capacity at 0 rpm or right from a standstill condition.

Unfortunately, the torque of a motor is directly proportional to its size. Thus, if you want more torque, you will have to increase the size of the motor. This is counterproductive as you would always want a smaller motor to reduce the weight of the car. Thus, a single reduction gear is used to increase the torque output of the motor while reducing the speed.

The Nissan Leaf has only one of these motors driving the front two wheels. Thus, during turning, it is still important to rotate the wheels at different speeds. This is where the differential comes in. A differential placed on the front wheels is often called a Transaxle.

The working of a differential is quite complicated. In essence, it ensures that the wheels of the same axle rotate at different speeds. This helps them cover different distances in the same amount of time. In more advanced electric vehicles, there might be a motor operating at each wheel. In such cases, you don’t need differentials as the motors adjust their speeds accordingly during turning.

To summarise, the transmission of the Nissan Leaf consists of a single-speed reduction gear coupled with a transaxle to distribute power to the front wheels. You might be wondering, with such a simple transmission system, can gearbox problems still occur in the Nissan Leaf? Well, the possibility certainly reduces. However, one of the most common problems faced by people using this vehicle (or similar ones) is leakage of transmission oil.

Transmission Oil Leakage

Every transmission system consists of gears meshing with each other to either increase or decrease the torque output. In some cases, they even help reverse the direction of rotation. Since these metal parts are constantly in contact, they are often immersed in oil. The oil prevents them from wearing out quickly and reduces the frictional losses of the system. However, where there is oil, there can be a chance of leakage.

You might be wondering how serious this issue can be. For starters, a leaking transmission may cause a foul smell due to its burning. While the chances are low, this might also turn into a flammable situation. Even if it doesn’t, you might have to deal with a slight clinking sound while you drive. Consequently, due to a reduction in transmission fluid, there might be high wear on your gears leading to a slight loss of power while operating the car.

How do you identify the problem?

There are several ways to identify transmission problems in the Nissan Leaf.

• Be on the lookout for the Electric Shift Control System warning light. This warning light is an indication of any transmission problems that your car may be facing for the time being.
• The second way to identify this problem is to be on the lookout for any foul smell coming from your car while driving. This may be caused due to the transmission fluid burning after reaching places it shouldn’t have.
• The most tell-tale sign that there is a transmission fluid leakage is that you would see the car leave a trail of liquid behind when you drive the car for a bit. Usually, the transmission oil has a reddish hue.
• Finally, you might be able to hear a clinking sound from your transmission when you drive. This might have been harder to notice with an actual engine due to its noise. However, thanks to the silence offered by electric engines it is easier to hear this sound. It is caused due to the metal-on-metal contact of the gears when the amount of lubricating oil is diminished significantly.

How to fix a Nissan Leaf Transmission Oil Leakage Problem?

A gap in the sealing gasket used to seal both halves of the transmission case can cause oil leakage. This can occur due to multiple reasons. Most of the time, a manufacturing defect causes this flaw. In this case, it is important to take the transmission out of the car and then re-apply a new sealing gasket.

Depending on the condition of the oil there are three possible courses of action for it –

• The first idea is to just top-up the oil. If the problem was caught early on with minimum leakage, all you need is some extra oil.
• The second fix is to replace the oil completely. This is important especially if the oil had some metal or other dirt particles in them which hamper the lubricating action of the oil.
• Finally, the most extensive repair is to replace the oil and flush the transmission case. This will get rid of any excess metal particles or debris that are stuck to the transmission case. These elements would have spoilt the new oil too and thus it is important to clean the case completely before adding new oil.

Finally, the worst-case scenario is to have to replace some of the transmission gears due to high wear. However, this is most likely never to happen as leakage of oil to this level is unprecedented.

Final Thoughts

Hopefully, this helps you get an idea of the transmission problems in a Nissan Leaf. While the problems can be multiple, usually the culprit is the same – a leakage of transmission oil.

Now that you know how to solve the problem, you may be able to fix the problem by yourself. At the very least, you will understand when the mechanic is trying to exaggerate the problem to get more money out of your pocket.

Last but not the least, keep an eye on the Electric Shift Control System warning light. It will let you know when you or a professional need to have a look at the powertrain system. You know what they say, “a stitch in time, saves nine”.