A torque converter is a component in automatic vehicles that lets fluid pass to the transmission, so the engine works even when it is stopped. This means a torque converter is a hugely significant part of automatic cars.
When it is not working correctly, you will start experiencing several problems including shuddering, screeching sounds, slipping transmission, and many others.
That’s why it is essential to know how a defective torque converter starts to manifest. It will not only tell you that it is time to replace it, but it will also help you what may be causing it.
If you are interested in learning more about torque converters and the problems they may cause – this article will be helpful for you.
What is a Torque Converter?
In short, a torque converter is a coupling that transfers torque or power from the engine to the transmission using fluid. It is fixed to the “flex plate” that spins thanks to the crankshaft.
You can find it, usually, between the engine and the transmission so it an essential part of the movement of an automatic car.
But this is only an overview of what a torque converter does. In reality, it is far more complex.
Here, we tell you the three processes a torque converter is responsible for:
Transferring Torque from Crankshaft to Transmission
Let’s start with the internal combustion of engines. This creates torque power by burning fuel, which eventually the pistons use to move the crankshaft. The rotation power in the crankshaft finally goes to the transmission, but it needs to pass first through the torque converter.
The torque converter uses this torque force to move a series of blades. These propeller blades will push transmission fluid into a series of impeller blades that connect the transmission to the input shaft.
Now that the liquid is in the input shaft, all the hydraulic pressure that comes with it will tell the gear and the speed of the car.
Of course, it all depends on how much force was sent from the engine and how the crankshaft responded to it by sending power to the torque converter. This is what happens when the car is moving.
When the car is not moving, the impeller blades of the converter will slow, and all the fluid will instead go into the transmission pump. This means that while the blades are not working to move the car, the pump will keep pushing the liquid around.
The fluid will move away from the pump into the stator, a pump-like wheel that using finned blades will move with the force of the fluid. The stator then pushes the liquid back to the pump, so the engine doesn’t stop when stationary.
This process will repeat itself, moving the fluid from the converter to the stator back and forth through the impeller blades until the car starts to accelerate again.
Acceleration after Stationary
Once acceleration steps in, the converter starts to spin alongside the stator but using the torque force from the engine. This repeats the process of moving the fluid around so the crankshaft can transmit the torque to the transmission.
Once all the transmission gears are starting to work again, and the vehicle is cruising, the clutch-like effect will lock using all the power of the torque converter to move the car.
Eventually, the whole fluid will go through the converter to the transmission and make the car reach higher speeds until it is a moment to stop again so the clutch-like effect repeats.
Common Torque Converter Problems
Now that you understand what a torque converter does, it will be easy to understand the many problems that can arise with it. But this will also tell you that most of the issues related to the torque converter can also be connected to many other parts.
To make it easy for you, we made a list of common difficulties with this part so you can be more confident when diagnosing your car:
As said before, problems linked to the torque converter can also be connected to many other parts of a vehicle. Overheating is one of these issues that can come from a wide array of problems. However, it is also one of the main things that happen when the torque converter is not working correctly.
This happens when the torque converter is not sending enough fluid to the transmission. Eventually, the transmission will start to overheat and make your engine work deficiently.
This may be a problem linked to a defective solenoid too, but also when the car has low fluid levels. Make sure to check fluid levels before doing anything else.
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The torque converter may start sending too much or too little fluid to the transmission when it is faulty. This causes the transmission to slip of the gears or delay when you accelerate.
In the long run, you will feel how the car uses more fuel than usual, which is a clear sign that not enough force is being transferred from the engine to the transmission.
This could also be linked to low fluid levels, so be sure to check them before replacing or going over the torque converter.
When you are driving your car frequently, and it starts to move weirdly up and down as if you were passing through bumps in a flat road, it probably means you have a defective torque converter. This could also be linked to a bad transmission system or problems with the CV axle.
But shuddering is one of the more severe problems with a torque converter you should be careful about.
Even in the slowest speeds (30 to 45 MPH), shuddering can happen, and if it does, you’ll need to check the transmission and torque converter as soon as possible. Because this is a sign it is close to breaking down and not working again.
Contaminated Transmission Fluid
The automatic transmission fluid (ATF) is the one that passes from the torque converter to the transmission to transfer the torque power. This liquid, however, can get old with time and create buildup which eventually damages the turbines, stator, or the torque converter itself.
If you want to know if the torque converter is working deficiency because of this, you can take a look at the transmission fluid and see whether it looks clear or dirty. When the liquid looks dark or with small pieces of black material, then it’s probably contaminated.
You can fix this by changing the fluid. If the dark colors or debris come back again, it means you may need to replace the converter.
Higher Than Normal Stall Speed
The stall speed is the velocity at which the engine works when the car is stationary. This RPM speed is used to keep the engine working even the vehicle is stopped, but also the limit at which the engine can go when there’s no movement.
When the car stops, the transmission will receive the fluid from the torque converter which will prevent the transmission but keep the vehicle on.
But when the converter is not functioning correctly, the stall speed will increase because the fluid is not reaching the transmission fast enough to prevent over acceleration.
If you feel this is happening to your car, it is recommended to take a look at the car’s manual and see what the normal stall speed is. After doing this, you can find out whether the RPMs are higher than usual, which probably means the torque converter is malfunctioning.
Clicking or Screeching Sounds
Most sounds that are not the normal sound of an engine always bring preoccupation to the drivers. However, there’s a specific clacking or screeching sound that comes from the torque converter that means it is not working as it should. And it could be disastrous.
When a loud screeching sound happens from the engine, it means there’s metal-on-metal contact that’s probably damaging something inside.
When it is the torque converter, you’ll have to stop the car immediately and prevent any loose metal part from going into the transmission which may eventually not only demand a torque converter replacement but other critical parts too.
Causes for a Torque Converter to Malfunction
We don’t recommend people to assume that the torque converter is the reason for their problem. However, most of the previous issues can occur when something in specific with the torque converter happens.
Here, we explain some of the main difficulties that could cause the torque converter to malfunction:
Broken Needle Bearings
The needle bearings separate the impeller, the stator, turbine and the housing of the converter. Sometimes, these needle bearings that are all around can break or get damaged leaving metal parts or fragments to get into the transmission fluid.
Eventually, these fragments will travel all around the transmission system and cause the usual screeching or clacking metal-on-metal sounds.
Cracked or Tore Torque Converter Seals
The seals on the torque converter are part of what keeps the transmission fluid or ATF inside. But when any of these seals get damaged, cracked or tore, you will start experiencing fluid leaks.
These leaks mostly come from the bell housing, which can eventually reach the floor. When this happens, you’ll lose transmission fluid that ultimately makes the system work deficiently.
Among the problems that you can experience when this happens are overheating because there’s not enough transmission fluid for the system to work with, Gear slippage because the fluid is not enough to keep the transmission static, or even power losses because there’s not enough fluid to transfer torque from the engine.
When this happens, you’ll have to change the seals.
Failing Torque Converter Clutches
The clutches or propeller and impeller attached to the torque converter can also get damaged or start wearing out with time.
When this happens, the torque converter can get jammed or overheat too much to the point of burning. Sometimes, these clutches can break completely or get stuck, making the car stay in a specific gear even when you are completely stopped.
Faulty Torque Converter Clutch Solenoids
Apart from the clutches in the converter, you also have solenoids. They make sure that enough fluid goes back and forth through the converter into the transmission, so enough torque power is transferred. As electronic components, they can start working deficiently with time, which could cause several issues.
But what mainly when these solenoids are not working correctly is that you’ll start suffering from irregular fluid pressures. These atypical fluid pressures in the transmission system can make the car stall, lose power when accelerating or just have bad fuel economy.
How to Test for a Bad Torque Converter
If you suspect your car is having a torque converter problem, you may just take it to the mechanic and be done with it. The expert will tell you what happens and how to fix it.
However, not all the time bringing the car to the mechanic is doable or a great choice. Instead, you can test and check the torque converter yourself.
The following steps will help you find out what’s probably happen with it:
1. Check Everything First
Before examining the converter, it’s important to make sure that the rest of the car is in good shape. From the fluids to the wheels, it’s crucial that you can get rid of as many possible issues as possible. Then you can park the car, put the transmission in stop, set the brake, and then get on with the testing.
2. Start the Motor
You’ll have to turn on the car and let it warm for about 3 to 5 minutes. Then shift the transmission to drive, but instead of letting the car drive off, you’ll push the brake all the way down to prevent the vehicle from moving.
3. Accelerate the Car
Now you’ll have to accelerate the car by pushing the pedal to the floor. This will increase the RPM until they are maxed out. Hopefully, this will let you know whether there’s a probably issue with the torque converter. But to do it without harming the transmission, you’ll have to push the pedal for a max of 5 seconds.
4. Listen Carefully
While maxing out the speed of the car, it’s essential to prepare your ear in search of any weird sound such as screeching, clacking or even the slightest clicking. Any of these sounds will let you know that the car is probably having a torque converter issue.
5. Watch the RPM
After hearing or not hearing any sounds when accelerating, you can take a look at the RPM readings. If the RPMs are higher than expected when the car is stationary, or if the RPMs are lower than they should when accelerating – it means the converter or engine are having an issue.
The stall RPM speed of a standard car should be from 500 to 700 RPMs under the max RPM speed of the vehicle. If it shows close to the maximum or lower than 700 RPMs, there’s a probable issue with the torque converter.
6. Try All Gears
If you tried the car stationary or drive and you didn’t notice anything weird, you can then go through the different gears. From reverse to first, second, and even N, to see whether any RPM reading or sound stands out. If you do, there’s probably something bad with the torque converter.
7. Drive the Vehicle
When none of the previous steps gave out any sign of a torque converter issue, you can then try to test the car by driving it. Sometimes, the torque converter can start working deficiently when it is indeed moving.
If you feel any loss of power, the engine over accelerating or stalling, shuddering, or any abnormal sound – then it is very likely the torque converter.
If you tried all these steps and you didn’t notice any of the previously mentioned problems with the converter, then it’s probable that it is working well with no problems.
But if you feel that it is not working correctly or that any other part of the car is having issues, we recommend taking the vehicle to a mechanic as soon as possible.
Considerations for Testing Torque Converter
While testing the car’s converter can be easy, sometimes it may be not. To prevent any issue when doing this, here are a few factors to consider:
- Before testing the car, it’s recommended to check with the car manual whether doing a transmission test is safe. Some transmission systems can’t hold a maxed out acceleration test when stationary and may eventually fail or break down.
- Even if you have a new transmission or a new car, it is essential to be careful and not overdo it. Remember to keep the push of the pedal to max out the RPM up to 5 seconds.
- Testing the transmission system of a car with traction control, any type of electronic transmission or anti-lock brake system can eventually damage the vehicle.
Torque Converter Replacement Cost
Now that you know what problems you can experience with a defective torque converter and what can cause them, it is time to understand how much replacing a converter costs.
First, let’s start by saying that replacing a torque converter should only be done when it is too damaged or broken to keep working. While repairing the converter is possible by a technician or mechanic, the cost of doing it can be higher than buying a new one. We recommend taking your car to a repair shop and ask for an opinion before deciding whether to repair the torque converter or replace it.
One of the good things about replacing a converter is that you can do it yourself. This will reduce the labor cost and probably the whole waiting time. However, you’ll still be looking to spend from $100 to $500 or even more depending on the price of the converter for your car.
While the torque converter can be a little inexpensive depending on your car, the labor cost of mechanics is not.
This can take up to 10 hours in a repair shop, even with the right tools and experienced technicians, which means the process won’t be anything close to cheap. Most mechanics can charge up to $1000 for replacing this part.
When replacing the torque converter, you’ll also have to change the TFA or transmission fluid. This could cost as little as $25 or even less. Whatever you do, though, there’s nothing better than asking for expert & trusted advice before deciding what to do with your car.
To Conclude, Don’t Let a Torque Converter Damage your Car!
If you reached this part of the article, it is very likely you are already familiar with the process of testing the torque converter, looking for the possible issues, and how much the replacement costs & how much time it takes.
All this information will help you prevent any torque converter issue from damaging your car in any way. If you start experiencing any of the previous problems or have even the slight suspicion that this part is malfunctioning, don’t waste any of your time and try to fix it as soon as possible. You won’t regret it.
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