5L40-E common valve failure and its solution

The 5L40-E is a GM 5-speed gearbox used on some models of the Cadillac, such as the BMW 323i, 328i, 525i / 530i, 528i, 3 Series, X3, X5 and Z3 and Z4. This article describes some of the common symptoms of wear and tear caused by valve bodies such as TCC lock slip, transmission ratio fault codes, gearboxes and torque converters overheating, reverse gear delays or no reverse gear, reverse lock valve card issuance, etc. As you can imagine So many phenomena may come from the same point of failure of the valve - TCC lock regulator? In the 5L40-E valve body, the OEM's original TCC regulator does not have a sleeve as shown in Figure 1 and the spool moves directly in the valve bore. Its role is to drive the TCC solenoid valve will be the main oil pressure into the converter lock-up circuit and adjust the size of the lock-up oil pressure. Since the hydraulic signal generated by the TCC solenoid valve is a high-frequency pulse signal, the TCC pressure regulating valve oscillates continuously and continuously under the driving of the TCC solenoid valve, thereby easily causing wear. It is noteworthy that the two ends of the valve wear different forms, resulting in the phenomenon of failure is also different. It will be over-worn on the cylindrical surface of larger diameter near one end of the solenoid valve, causing the solenoid valve signal not to move the TCC regulator to its normal position, resulting in insufficient pressure regulation of the lock-up oil pressure resulting in no lock Stop, lock slipping or locking and other issues. At the other end of the TCC regulator (the spring end of the valve), the valve will also wear out the corresponding valve bore area. If there is excessive wear of the valve bore there, the adjustment of the lock-up oil pressure will be reduced and the High locking oil pressure (because the locking oil pressure is from the main oil pressure), resulting in a locking shock. Let us analyze the impact of this valve on the reverse. OEM TCC pressure regulator valve will often hit the adjacent solenoid valve will stop, as time passes on the TCC solenoid valve on the easy to crash, debris falling from the filter will stay in the inverted Gear locking valve, resulting in no reverse gear appears. Everyone may be unfamiliar with this reverse lockup valve in the 5L40-E. Its role is to prevent the car suddenly move into a reverse gear when moving forward, do not allow oil into reverse gear to protect the gearbox. Under normal circumstances, if the car moves forward more than 3MPH speed, and you suddenly engage the reverse gear, the reverse gear lock valve will work, the transmission will automatically enter the neutral state. If now the reverse gear shut-off valve is stuck, there is no reverse gear even when the reverse gear should be used. So TCC pressure regulating valve will actually produce reverse delay or no reverse gear. To avoid this failure, a protective spacer (shown in Figure 1) is included in this SONNAX retrofit kit (SONNAX part number 55211-04K), which effectively prevents the TCC regulator from meshing the TCC solenoid valve broken. Mentioned earlier not only the valve will be worn, and the valve hole will be worn, in order to completely solve this problem, you need to repair the valve hole, and to eliminate the original spool caused eccentric wear and partial load factors. As a result, SONNAX redesigned this TCC regulator with a highly wear-resistant aluminum sleeve on the outside of the valve so that the relative movement between the spool and valve bore becomes a movement between the spool and sleeve , And the lubrication between the valve and the valve sleeve and overloading the effect of partial re-design can be well controlled, greatly reducing the probability of wear and tear. In order to join the valve sleeve, and to repair the valve hole that was worn, the valve hole needs to be reamed. So how to accurately locate reamer in the reaming process? This is a key issue. This is designed to use the universal valve body fixture, and more and more body repair in the future need to use this universal fixture, which together with the reamer positioning sleeve can easily and accurately locate the reamer. Once the reamer position is accurately located, the actual reaming takes a few minutes to complete. Finally, note that when installing this valve pack, be sure to use the TCC spring included in the pack. Because this replacement TCC valve is smaller than the diameter of the OEM, it needs to work with its matching spring to return to the correct TCC lockout pressure specification.

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