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If you’re asked to list down car parts, the ones that will probably pop into your head first are the bodywork, wheels, or the engine. Some more dedicated gear heads might mention things such as the gearbox or the suspension. However, it is rare that the torque converter finds its way into these types of conversations. In spite of this, it is actually a vital part of the car. Without it, your car won’t run as smoothly as you would want it to. You could even call it an unsung hero among car parts.

Turbine of an automatic transmission

What Does a Torque Converter Do?

Let’s discuss what a torque converter is and why it’s important. But before that, we should have some basic knowledge of car transmissions. A car with a manual transmission has a special part known as the clutch. This connects the engine and the transmission. This connection is important, as it allows the vehicle to come to a full stop without killing the engine. To put things into perspective, without the clutch, the engine will have to be restarted every time you stop your car. On the other hand, cars with an automatic transmission have no clutch that separates the engine and the transmission.

This is where the torque converter comes in. It allows the engine to move somewhat independently from the transmission. Not many people know about this car part and its functions, but it is very important. It consists of four major components: the pump, turbine, stator, and transmission fluid. These parts all come in a highly durable housing that allows the entire mechanism to be connected to the car’s flywheel. This connection allows the torque converter to move at around the same speed as the engine does.

The pump of the torque converter is made up of small fins that make the connection to the flywheel possible. They also serve to pump the transmission fluids to the outside of the mechanism. This creates a vacuum that in turn delivers more fluid to the central part of the device. This fluid then enters the next part of the torque converter: the turbine. Once here, the moving fluid causes the transmission to spin, which results in the car moving. This happens when the fluid exits the turbine in a different direction compared to when it entered.

The transmission fluid is not allowed to come into contact with the pump at any point, though. This is where the stator comes in. The stator is placed in the center of the torque converter. It has large blades that redirect the fluids coming in and out of the mechanism before they get a chance to hit the pump. More modern iterations of the torque converter may come with a lockup clutch. This combines the two separate halves of the torque converter, which improves the car’s efficiency because of reduced slippage.

When your vehicle is slowly coming to a halt, the torque converter only receives a small amount of torque. This means that only a small amount of force is needed on the brake pedal to bring the car to a complete and total stop. Meanwhile, pressing the gas pedal delivers a large amount of torque. This is why, to bring your car to a stop, you need to press on the brakes harder if you are moving at a faster speed.

The Benefits of a Torque Converter

Now that we’ve discussed what a torque converter is and what it it does, let us take a moment to talk about the benefits of having this mechanism in your vehicle. For starters, torque converters allow for automatic transmission vehicles, which a majority of people agree are easier and more comfortable to drive. It also allows the car to do a full stop without stalling the engine, which makes driving a more efficient and pleasurable experience. A frequently stalling engine is also indicative of a car having a major mechanical problem.

When the engine is rotating at a faster rate compared to the transmission, the torque converter also acts as a torque multiplier. In this scenario, the torque is actually multiplied by at least two or three times the original amount. However, if the engine and transmission move at the same, or close to the same rate, there is actually a small amount of power wastage that occurs. This is the reason why manual transmission cars have better gas mileage when put up against their automatic counterparts that have torque converters installed.

Torque Converter on the table

Signs of a Bad Torque Converter

But how will you figure out if your torque converter is not functioning the way that it’s supposed to? The first, and for a lot of people, most obvious sign of a bad torque converter is when the gears in the car’s transmission begin to slip. When your transmission slips, it would feel like you’re driving over ice or up a hill with a heavy package in the trunk. Another sign of a slipping transmission is having little to no traction despite the engine already revving up. This also causes a car to jerk into gear or, in a number of cases, jump forward. Delays in acceleration as well as an inability to reverse have also been attributed to this issue.

These slips happen if your car’s torque converter does not generate enough pressure to control the flow of the transmission fluid. Having too much or too little fluid in the transmission will mean that its gears will function in an unexpected manner. This isn’t always solely caused by a faulty converter, though. Make sure to check first if you have enough high-quality fluid running in your car’s system. Another telltale sign of a faulty torque converter is dirty transmission fluid. If there are black flecks present in the fluid, then you should replace that also. Doing so might just end up saving you a lot of money.

The next sign of a torque converter problem is if the vehicle shudders at lower speeds – around 40 miles per hour. This may feel like you’re driving over a series of small humps when in fact, you are only driving slowly on a flat surface. If you experience this while driving your car, then it may be time to look into getting your torque converter replaced as soon as possible. You should also get a new one if you feel your transmission surging or lagging, especially when you are driving at a consistent speed.

Once you feel these problems in your car, stop using it. Driving a car with a troublesome torque converter does not only exacerbate the problems already present, but it is also extremely dangerous. This could end up costing you a lot of your hard-earned money. If your car breaks down in the middle of the road, you will not only have to pay to get your car fixed, but you also have to pay for it to be towed to the repair shop. Driving with a damaged torque converter may also cause debris to get into the other parts of the car, causing them to break down as well.

Testing a Faulty Torque Converter

Another way to see if you have a broken torque converter is to put it to the test. Before doing so, however, you should first see if your car’s transmission would be up for it. Some newer transmission models could be damaged by this test, so do as much research as you can on yours. It’s a good thing there are several resources available for you to check what you have. You simple have to input your car’s make and model, its engine size, and the year it was manufactured. If you see that it can handle a speed-stall test, then by all means carry on with next steps. However, you should proceed with caution if you have a later model transmission in your vehicle.

The next step in testing your converter is checking your fluids. Make sure that you have an appropriate amount of clean transmission fluid in your car’s system before it undergoes a stall test. If you can, you should also check on your wheels as well as your parking brake. You should also have a tachometer that is visible from where the driver is seated. This lets you measure and collect the data needed for this test. If you do not have this, install one first before proceeding to the next part.

Now it is time to start your engine. Once you have done this, you need to make sure you’re holding the brake pedal down. This is because you will have to press on the accelerator and the brake pedal at the same time once your engine starts. This lets you measure your stall speed. Do not accelerate for more than two or three seconds. If you press on the accelerator for more than five seconds, it may cause the transmission to get blown out. This will cause even more damage to your vehicle.

The RPM (revolutions per minute) measured once the car’s engine maxes out is its stall speed. If the stall speed measured is lower than what is specified for your torque converter, then it may be the beginning of its end. On the other hand, if the stall speed is higher than expected, it may be because the transmission is beginning to slip. You should replace it as soon as possible if that is the case. However, if the RPM you got on your test meets what was expected, try looking first for the problem, or the cause of it, elsewhere in your car.

Transmission Torque Converter

Causes of a Broken Torque Converter

A malfunctioning torque converter could be caused by many factors. For instance, if the needle bearings that separate the mechanism’s components are damaged, this could cause friction as well as weird clanking sounds to happen from inside the housing. If the torque converter’s seal has malfunctioned, then it would cause the entire mechanism to operate at a much higher temperature. If this happens, the fluids inside might spill or get dirty. This contaminated fluid might even reach and damage other parts of your vehicle.

A faulty clutch solenoid could be another cause of a broken torque converter. If this part does not function as expected, then the fluids will be unevenly distributed. Bad needle bearings can also be at fault in this situation. If these don’t allow the turbine and stator to move freely, then the torque converter won’t be able to do its job properly. If one of the clutches in the converter does not properly connect with the engine or the transmission, problems may also arise due to excessive friction.

How to Get it Fixed

Once you’ve determined that the torque converter is the one causing your car problems, it is now time to talk about how to get it replaced. First and foremost, a faulty torque converter is not something that an average garage mechanic should get his hands dirty with. It is an extremely delicate and complicated piece of technology. There also aren’t a lot of tutorials showing people how to do it, so merely guessing how to do it could cause even more costly problems.

Leave this to the professionals. This may cost more money upfront, but it actually costs much less in the long run. A certified car mechanic would normally charge $600 to $1000, or a figure around that range, to replace a broken torque converter. While the part itself is relatively inexpensive compared to the price charged – around $150 to $300 – the labor adds a lot to the total. It can take anywhere between five to ten hours to replace a problematic torque converter because the entire assembly has to be taken out for that to happen. Replacing dirty fluids may or may not be included in your bill. This depends on which shop you go to get the needed repairs done.

You now know how to deal with these problems if they ever arise in your vehicle. Don’t forget that if you experience any of the warning signs of a broken torque converter, then you should stop using your car immediately. Also remember to get your repairs done only by a certified professional.

Sources:

  1. Torque converter – Wikipedia
  2. How Torque Converters Work – HowStuffWorks

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