Restoring the BTR M78 automatic transmission pump stator during cranking

Restoring the BTR M78 automatic transmission pump stator during cranking

One of the components subjected to the most severe stress during vehicle operation is the oil pump. The risk of failure of this component is quite high. Potential problems can range from a drop in system pressure to complete failure.

The weak point of the 6-speed M78 transmission is the pump with planetary gear, which is destroyed by increased torque and vibrations from the torque converter.

The same chain is in the oil pump - a broken gear leads to damage to the pump itself.

In case of rotation of the stator hub and sun gear of the front planetary gear of the DSI M78 pump, the machine comes to a complete stop

The reason for the stop is the rotation of the front sun gear.

During the process of displacement of the stator along the axis and around the axis, the locking pressure of the torque converter is lost.

Diagnostic codes that accompany this defect:

* p 0741 (often found on SsangYong Kyron/Actyon) means " Torque Converter Clutch Circuit Malfunction - Stuck in Disengaged Position ." The transmission control module (TCM) detects slippage of the clutch . Common causes include contamination of the valve body, wear of the torque converter clutch, faulty TCC solenoid, or faulty wiring.

* P0744 - indicates an intermittent fault in the torque converter clutch (TCC) control circuit. This is a critical error, indicating problems with the solenoid, wiring, contamination of the valve body, or wear of the torque converter itself.

* p0716- Incorrect signal from the input shaft speed sensor (TSS - Turbine Speed Sensor). This causes hard shifting, limp-in mode, and the Check Engine light. Common causes: wiring, dirty/failed sensor, metal shavings in the oil

Repair of the BTR 78 oil pump includes the following operations:

• manufacturing of reactor shaft sleeve;
• bushing installation;
• restoration of splines in the oil pump cover;

as well as control operations:

• alignment check;
• Checking the operation of the plungers in the oil pump cover.

Completion time: 2-3 business days.
The cost of this work is $200.

It is impossible to foresee or avoid this failure.

During prolonged operation of the transmission with a faulty pump and input shaft, the torque converter ( https://akpp.com.ua/TQREPBTRM78 ) may also fail , the failure of which may lead to the failure of other automatic transmission components - brake bands, friction elements (the independent service life of which is from 300 thousand km), etc. Individually, the above-mentioned elements do not fail.

As soon as the first vibrations appear, indicating insufficient oil pressure in the system, you should immediately contact a service center, where they will carry out diagnostics and repair the automatic transmission.