SsangYong New Action, Korando C

Valve body repair DSI M11. Solenoid regeneration.

All known facts.
The main quality characteristic of the automatic transmission is the smooth running, i.e. no impacts,thumps, slips and long shifts between gears. If at least one of the above types of malfunction occurs, it is necessary to contact the service to solve the problem as soon as possible. Further operation of the automatic transmission with a defect can lead to the failure of a larger number of mechanisms and parts of the automatic transmission

Diagnostics.
To determine the type of fault the diagnostic tool is used. Then, the valve body is removed and a visual assessment of its condition is made. An obligatory stage in the diagnostics of a hydraulic unit is testing its electromechanical control valves (solenoids).

This is how a valve body looks like

This is a solenoid.

After dismantling, the solenoids are alternately tested on special stands

Stand number 1

Stand number 2

For each solenoid, a plunger state plot is plotted over the entire range of the control signal values.

Plots of a working solenoid

The graph of the failed solenoid. Unstable work, the presence of flat parts of the stuck plunger "steps."

Unstable operation of the valve body solenoids causes faults such as thumps, slips and delayed gearshifts. The lack of smoothness in the solenoid's operation is explained by the graphs of the faulty solenoid: the steps of the graph are manifestations of the malfunction. The type of failure of the valve body (thumps slips and delayed gearshifts) depends on the number of the solenoid and its location in the valve body

Solution.
The failed solenoids are to be replaced or restored. The method of solenoid recovery was developed by the specialists of Maktrans companyon the basis of many years of experience in valve body servicing .

The essence of the methodology
The electromechanical valve consists of a cover with a bushing, a return spring, an insulating ring, a core and a housing. The housing includes a solenoid coil, a control terminal and a guide sleeve.

During operation, the solenoid bushings are worn out by the action of fine particles (metal shavings, oil oxidation products, etc.) which get into the oil inside the valve body housing. As a result of the wear out, the central bore of the bushing acquires an eccentricity (displacement of the hole center relatively to the normal one).When the center of the hole of the guide bushing is displaced from at least one side of the solenoid, the axis of the core movement can be skewed and, consequently, the core jam occurs during its movement inside the coil of the solenoid. Such jams are marked on the chart of the unstable solenoid by flat section.

Guide couplings with 12 hours wear

To restore the work of the solenoid, the failed couplings are replaced for new ones. The new couplings are made by the specialists of the Maktrans company

Disassembly of the solenoid, replacement of the bushings for the new ones and assembly (closing) of the solenoid are carried out by a special tool developed by the specialists of Maktrans company. After assembly, the solenoid with a new set of bushings is tested for compliance with operating parameters. After testing regenerated solenoid is installed in the valve body.Further, the operation of the automatic transmission is tested on the go.

Result.
Solenoids restored by the technique of the specialists of the Maktrans company, respond to the operatonal parameters of solenoids for DSI-6 M78 и DSI-6 M11 automatic transmissions . The service life of this solenoid after recovery corresponds to the life of the new one at a relatively lower price.