Problem of Seal Leaks in Torque Converter
A torque converter (TC) is an indispensable part of modern automatic transmissions and CVTs which plays an important role in their operation. In many cases, TCs fail much earlier than the automatic transmission. Frequently, the problem resides in the seal leakages. We will consider this problem in more detail.
So, before we discuss possible solutions of the TC seal leakage, it is necessary to figure out the purpose of this element in the TC arrangement. The TC ensures the transfer of torque from the engine to the gearbox. The seal, in turn, is responsible for prevention of ATF leaks.
That’s how the torque
converter seal looks like
Moreover, the torque is not only transferred via the TC, but it also gets converted. After that, the torque is transferred to the shafts of the gearbox. The torque transfer is implemented with the help of the ATF which actually turns out to be the operating fluid in the TC and connects two wheels with two blades. During operation, TC elements wear out, resulting in leaks and other types of damage. If we talk about the TC design, it is a completely sealed unit with two rotating turbines which transmit torque (via ATF) from the engine to the gearbox.
Learn more about the
torque converter operation
Due to high loads, the TC actively wears out and fails earlier than the transmission itself. Frequently, problems occur because of ATF contamination caused by the damage of friction linings of the torque converter lock-up. As a result, mud from the TC penetrates the gearbox leading to the damage of the valve body and its channels as well as solenoids wear. Another common problem is the seal leakage. It is important to understand that the complete TC repair requires not only professional skills and spare parts, but also special-purpose equipment. In other words, it is very problematic to perform a comprehensive repair independently in the garage.
However, if the issue is limited only to the seal leakage, you can deal with the issue by yourself. The TC leakage can be caused by the following reasons:
- ATF overheating, fluid shortage in the oil pump;
- Problems with the oil pump bushing, wear of the seal itself.
In many cases, the seal leaks because one
problem in the TC causes the other one as a chain reaction: friction lining
wear-out –> ATF contamination –> valve body failure –> failure of the
TC lock-up –> slippages –> ATF overheating –> bad impact on the oil
pump –> seal leaks. Fluid leakages lead to the ATF level reduction and
pressure drop in the gearbox.
If the mileage of your car reaches up to
200-250 thousand kilometers, the seal leakage can be considered as a natural
process of wear. However, leakages of ATF via the seal at the mileage of 70-80
thousand kilometers cannot be considered normal. If you ignore even a slight
leakage, you can significantly reduce the service life of the transmission
itself, since the faulty TC will directly affect the transmission condition.
To put it simply, seal leaks lead not only to the ATF level reduction, but also to wear of the shaft and the oil pump. The oil pump malfunction means that the operating pressure of the lubricant will be affected, i.e. friction plates and shaft axles won’t get enough fluid. As a result, it can lead to the premature transmission wear. Thus, the seal change is an important procedure which should be performed timely and accurately.
How to Replace the
Torque Converter Seal
If the seal change is inevitable, you have to know how to do it properly. First of all, it is necessary to take down the automatic transmission and the TC to replace the seal. You have to unscrew retaining nuts of the TC to the flywheel. To remove the TC, you may need to dismantle the starter and the protective cover. After dismantling the gearbox and the TC, you can remove the TC. In fact, the unit is removed from the shafts. After that, you can remove the seal with the help of the L-shaped remover tool for retaining rings. After replacing the worn seal with the new one, you can start the assembly procedure.
Torque converter seal
location
It is important to bear in mind that if the seal replacement doesn’t solve the issue, then it indicates that something is wrong with the pump. For this reason, it is recommended to perform a complete diagnostics of other components simultaneously with the seal replacement, because after installing a new seal it often turns out that the problem may be caused by shaft vibrations. In such cases, the diagnostics can save you time and money. It is obvious that the seal leakage is quite a serious issue. ATF leaks indicate not only the TC failure, but also that the faulty TC can cause general wear of the gearbox. For this reason, it is necessary to replace the automatic transmission seal when you notice even the slightest signs of leakage. This procedure can be performed independently. The main thing here is to be prepared for removal of the gearbox and the TC.
Check out how the
torque converter is checked for imbalance
However, it is worth noting that the full-scale
TC repair is a complex procedure performed with the help of the special-purpose
equipment. To put it briefly, during such procedure the TC is cut open,
inspected for defects, worn elements are replaced, and then the TC is welded up
using a special welding method. Finally, the TC is checked for leaks and gets checked
for imbalance. As a result, if all procedures are performed correctly, you will
significantly prolong the service life of the TC (70 % of the new TC resource).
Usually, the TC repair turns out to be less expensive than the new unit.
