Unlike vehicles with a manual transmission, cars and trucks equipped with an automatic transmission do not have a manually operated clutch. Instead of it, they come with another amazing device, known as a torque converter. It takes the place of a clutch, transferring power from the engine to the drive wheels via the transmission.
By design, your torque converter is a fluid coupling that allows the crankshaft to spin independently of the transmission. When your engine is idling, the hydraulic fluid pressure inside the converter is low, which allows a very small amount of engine torque to pass through the converter. This means you can keep the car from moving with just a step on the brake pedal. However, once you press on the accelerator, the amount of power transferred via the torque converter will significantly increase, causing your vehicle to move.
A typical torque converter consists of four main components, including an impeller, a turbine, a stator, and a converter clutch. An impeller features blades on one side, which performs the function of a fluid pump, causing transmission fluid to circulate through the torque converter. It is attached to the flywheel and spins together with it. Just like an impeller, a turbine also has blades that face the impeller’s ones. The circulating of the fluid causes the turbine to rotate and since it is attached to the transmission input shaft, the latter spins along with the turbine. As for a stator, it is attached neither to the impeller nor to the turbine. Placed between them, the stator redirects fluid flow back to the turbine to increase its performance. Last but not least, a converter clutch serves as a mechanical link between the engine and the transmission to prevent slippage.
A torque converter is an essential part of a vehicle’s drivetrain. If your torque converter fails to transfer engine power to the transmission, your vehicle won’t move. Fortunately, this will happen only if you ignore common signs of a failing torque converter listed below.
A malfunctioning torque converter can cause improper fluid flow, which may result in transmission slippage and its overheating.
Reduced performance and poor acceleration
Poor acceleration and performance can be caused by a faulty stator. If it fails to spin or malfunctions, the fluid flow from the impeller to the turbine will be reduced, resulting in a lack of torque delivered to the transmission. Your engine will have to run at high speeds to move the vehicle. This may also lead to engine and transmission overheating and high readings on the temperature gauge.
If your converter’s needle bearings wear out, you can notice a whirring noise coming from under the hood. It should be especially noticeable when you’re running in gear.
If you notice reddish fluid underneath your transmission, this can be an indicator of a leaking torque converter. You should check the fluid level and inspect the transmission for leaks.
Illuminated check engine light
The operation of your torque converter is monitored by your vehicle’s control module. If it detects any problem, it will turn on the check engine light.
Shuddering at lower speeds
A lack of power caused by a bad torque converter may result in vehicle shuddering at lower speeds, usually from 30 to 45 MPH.
Torque converter replacement and repair
A torque converter is a complex device, so it should be diagnosed and repaired by a professional. He or she will scan the trouble codes stored in your computer’s memory and visually inspect the torque converter to make sure it is the only source of the problem.
Your mechanic may offer you to replace the entire torque converter if it is damaged or discolored due to overheating, or, for example, if your stator fails to spin at all or rotates in different directions.
Replacing a torque converter may cost you a pretty penny due to a lot of labor involved and expensive replacement parts. In addition, a faulty torque converter can be a result of a malfunctioning transmission, so it should be diagnosed along with your torque converter. In some cases, you may need to take a decision on whether your vehicle is worth repairing.