Sealed Transmission: Everything You Need To Know

You may have heard the dealer talk about sealed transmissions if you’ve been in the market for a new or used vehicle recently. But, what is a sealed transmission? Over the years, technology has made vehicles more efficient but much more complicated. The day of manual, stick shift transmissions is long gone.

Sealed transmission is a term that is here to stay since many vehicle manufacturers are making the change from traditional automatic transmissions to CVT sealed transmissions. In this article, you will learn everything you need to know about sealed transmissions and whether purchasing a vehicle that has a sealed transmission is right for you.

What Is A Sealed Transmission

First, what exactly is a sealed transmission? On a vehicle with a traditional transmission, there are easy access points so that the transmission can be easily serviced. However, this is not the case on a sealed transmission.

As the name implies, the transmission is completely closed and doesn’t have a traditional drain plug or even a dipstick. This is because the transmission fluid inside is advertised as lasting the life of the transmission, with no maintenance or change needed.

This sales pitch is only half true, and if you aren’t careful, taking this at face value could end up costing you tons of money. The transmission fluid will last the life of the transmission because when the transmission fluid begins to go bad, that causes the transmission itself to fail!

The Role of Transmission

To better understand what a sealed transmission is, first, we have to understand what it is the transmission does in the first place. The transmission controls how the power created by your engine is transferred to your drive wheels, allowing you to manage your speed smoothly.

It achieves this by changing gear ratios in a way that isn’t felt by the driver at all. Changing gear ratios allows the engine to propel the car faster while minimizing stress on the engine itself. A critical part of your transmission’s performance is the fluid inside.

The fluid in your transmission protects the integrity of its complex parts and helps with heat transference. Even in a sealed transmission, the fluid can degrade over time which can cause catastrophic damage to your vehicle. The spacing of the parts inside your transmission has to be very precise. Within a few thousandths of an inch!

Car mechanic drain automatic transmission oil.

Over time, tiny metal shavings from the inner components of your transmission get mixed in with the transmission fluid. This can throw off the spacing between components and excessive wear on the gears or belts of your transmission.

Given what you now know about transmissions and the role transmission fluid plays in the shifting process, it should be evident that when a car dealer says the word lifetime, it doesn’t mean what you think it does. Even with the advances in synthetic fluids, the fact remains that the transmission fluid will break down and get dirty over time.

When To Replace the Fluid in Sealed Transmission

In the past, vehicle manufacturers have recommended changing your vehicle’s transmission fluid roughly every 100,000 miles. More if your vehicle is often under heavy loads or exposed to extreme conditions. So how would you know if it was time to replace the fluid in your sealed transmission?

The downside to a sealed transmission is that a simple way of checking your vehicle’s transmission fluid doesn’t exist. Unlike more traditional transmission, there isn’t even a drain plug or a dipstick in a sealed transmission. Checking the fluid in a sealed transmission is a very technical task, and even the most seasoned do it yourself shouldn’t attempt this on their own.

Without being able to check your transmission fluid visually, the safest thing to do is to stick to a maintenance schedule. However, there are some signs to watch for that will let you know it is getting time to change out the vehicle’s transmission fluid.

Signs of Malfunction

One of the most obvious signs that a transmission is going out is grinding gears or what is known as slippage. When transmission fluid breaks down, it can cause the gears inside to grind against one another. This isn’t good for obvious reasons and makes a very noticeable sound, usually when accelerating.

Another cause for concern is what is known as transmission slippage. This is when the transmission seems to fall out of gear, and your vehicle reacts as though it is in neutral, often followed by the transmission suddenly catching again and causing a sudden jerk.

However, some sealed transmissions don’t have gears, like the Constant Variable Transmission or CVT. This transmission uses a series of pullies and a steel belt to control the gear ratio. Unfortunately, dirty or degraded transmission fluid can speed up the life of the steel belt causing it to break.

Continously variable transmission gearbox repair.

When this belt breaks, your transmission is useless and leaves you unable to accelerate or decelerate. The only option at this point is to have your vehicle towed and either; pay thousands of dollars for your transmission to be rebuilt, or replace the transmission altogether.

In Summary

The car manufacturer claims that the transmission fluid would last the transmission lifetime, but what does that mean exactly? For the manufacturer to make good on their promise, they probably only need the transmission to last the lifetime of the power train warranty. This can vary depending on packages but is very rarely longer than five years or one hundred thousand miles.

While that may be good enough for the manufacturer, that probably isn’t good enough for the driver. If you are planning on owning your vehicle for an extended period of time or maybe purchasing a used vehicle, it is important to know that a lifetime warranty is never what it seems.

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About Brock Rangel

Hi, I am Brock, and I am the lead editor/photographer for TheCarColony. I have been a mechanic for over 14 years now, and I am here to spread my car knowledge across the web!

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