What is a Transmission Flush?
The transmission flush is a process that makes it possible to clear the majority of old transmission fluid from the transmission of a motor vehicle. This process also helps to remove residue of older transmission fluid from the converters, coolers, and cooler lines that often are part of the design for the transmission. While there is some difference of opinion on whether transmission flushing is necessary when changing fluids, the proponents of conducting a regular automatic transmission flush point to several ways that the function and life of the transmission may be enhanced.
In a simple draining of old transmission fluid, a drain plug in the transmission is removed and the remaining fluid is allowed to accumulate in a pan. While this process does make it possible to rid the transmission of a significant amount of the older fluid, it does not thoroughly cleanse the system. The end result is that without a transmission fluid flush, there is still a fair amount of older fluid present. When this is the case, the older fluid will mingle with the new transmission fluid and thus dilute the effectiveness of the new fluid.
By employing a transmission flush, more of the older fluid is removed and the overall transmission system is cleansed. This means there is less residue to contaminate and weaken the new transmission fluid. The presence of fresh transmission fluid means less stress placed on the transmission itself, which in turn can prolong the life of the transmission.
While some people believe that a transmission flush may blow out the seals on the transmission, this is actually not possible. The process of the flush does not rely on pressure to flush out the residue of the old fluid. Instead, the method relies on using the pump of the transmission to gently introduce the new fluid into the system. As the new fluid enters the system, it begins to push the residue of old fluid out of the system. This means that rather than applying pressure that could damage the transmission, simple displacement is used to rid the system of the vast majority of the old fluid.
While it is possible to buy flush machines for home use, it is usually a better idea to have the transmission flush conducted by a qualified mechanic. While a transmission flush does cost a little more than simply draining and replacing the fluid, the investment can mean a smoother operation for the transmission and possibly minimize the chances for having to replace the transmission during the life of the vehicle.
Written by Malcolm Tatum
