There are several signs that you are in need of a torque converter repair.
The first sign is when you are experiencing some slipping. This means that when the fin inside of the transmission could be damaged or the bearing is causing the transmission to delay a shift. In other words, the transmission is going to be slipping out of gear. But this could also be caused because you have too much or have not put enough transmission fluid in the transmission. If this is the problem, then you are going to notice that you have a loss of acceleration. The fuel economy of the car is also going to be greatly reduced. It is normally going to be a good idea to check the amount of fluid that you have in your car before you take it to the shop.
The second sign is when the temperature gauge on your car is indicating that your car is overheating. When this happens, there is either going to be a problem with your torque converter or a drop in the fluid pressure of the car. You are not going to be able to transfer any power from the engine to the transmission if the converter is overheating. This is going to result in a poor response on your throttle and you will have excessive wear and tear on the internal workings of the transmission.
The third sign is when you are driving between 30 and 45 mph and you notice that your car starts to shudder. This is going to happen if the lockup clutch inside of the torque converter malfunctions. It is going to be very noticeable because it is going to feel like you are driving over a rough road with small bumps. It is going to feel this way because the converter is going to switch over to direct drive. It might not last that long and may start and stop all of a sudden but if it happens a lot, then you need to check out your transmission.
The fourth sign is that you notice that your transmission fluid has been contaminated. This is going to cause a lot of damage to the parts inside of the torque converter like the bearings on the stator, or the finds on the turbines. You are going to notice that there is a lot of black sludge, debris, or grime coming out of it. You will need to change your fluid immediately and if the problem keeps happening, you should have it checked by a professional.
The fifth sign is if you have a higher stall speed or gear engagement RPM. The stall speed happens when the torque converter is able to transfer power from the engine to the transmission. This means that is going to stop the speed of the engine from increasing if the output of the transmission is prohibited. If the torque converter is broken, then it is not going to be able to transfer the rotational force of the engine. This means that the transmission is going to take a longer amount of time to engage the engine.
The last sign is when the torque converter is making strange and unusual sounds. This is something that is going to happen every time that it is starting to fail. The bad bearings are going to make a whirring sound when the torque converter is no longer working. The broken turbine fine is going to make a clinking sound when the torque converter is starting to go bad and fail in your car.