Accumulator Piston/Sealing Ring C3, Replacing

Accumulator piston/sealing ring C3, replacing

Special tools:
999 5006 LIFTING BAR 999 5006 Lifting Bar
999 5033 SUPPORT 999 5033 Support
999 5460 Lifting hook 999 5460 Lifting Hook
999 5477 JOINT WEDGE 999 5477 Joint Wedge
999 5562 PROTECTIVE SOCKET 999 5562 Protective Socket
999 5972 FIXTURE 999 5972 Fixture
998 8670 DIAGNOSTIC KEY ST 998 8670 Diagnostic Key ST
951 2050 BEVEL PROTRACTOR 951 2050 Bevel Protractor

Preparations
Open the control system. See Inspecting / replacing solenoids Inspecting / Replacing Solenoids.

Information when working with valves and pistons

Seized valves and pistons - removal

Note! Cleanliness Pay particular care with cleanliness. The control system is very sensitive to contamination. Clean the workplace and tools before starting work. Never use cotton waste, cloths or paper that sheds threads and fluff. Dry and clean with compressed air. If you need to dry with a cloth , use chamois-leather.

Never under any circumstances pry out a valve or piston that is seized or jammed. Knock the valve housing against a piece of wood or plastic instead.
Parts difficult to access can frequently be removed using a magnet.

Checks when dismantling
Check when dismantling whether there are foreign particles in the control system. These may give possible clues concerning faults in the gearbox.

Measuring/checking the springs




Spring data can only be used to identify the springs during assembly. If, for example, the free length of the spring does not correspond exactly with the value in the table, this does not mean that the spring is defective. Whether a spring has approved characteristics can only be determined with special measurement instruments.

Note! When replacing parts in the control system, always check the gearbox designation and engine type.

Preparations




Place the control system on a clean bench.
Remove the gear selector slide so it does not fall out and become damaged.

Replace the accumulator piston C3




Remove:

- The cover plate with gasket. Check that the gasket is free from fault.
- Springs and modulator valve (1)
- Springs and modulator valve B1 (2)
- Springs and modulator valve C3 (3)
- Accumulator piston C3 with springs (C3).

Clean and check the valves and pistons.




Clean all metal parts carefully in cleaning fluid, type gasoline, paraffin or trichloroethylene. Dry with compressed air or lintless cloth.
Check that the valve opening is not worn or damaged.
Check that there are no signs of wear or damage on the valves and that the valves run easily in their bore. Valves can possibly be carefully ground using very fine emery cloth.
Check that the hole in the valve (2) is clean. Blow clean with compressed air.

Spring data for the accumulator pistons and valves
Engine B5254 S, B5252 S, B5234 S





Engine B5204 S, B5202 S





Engine B5234 T






Note! See also.

Replace the sealing rings on the accumulator piston.




Lubricate the new sealing rings using ATF oil.
Exercise care so the ends of the sealing rings are not damaged!

Install the accumulator piston with spring




Install the valves and springs.
Install the cover with gasket.
6 screws. Torque: 6.5 Nm .

Note! A too large tightening torque can cause setting in the control system resulting in seizing valves.

Finishing
Install the control system. See Inspecting / replacing solenoids Inspecting / Replacing Solenoids , Inspecting / replacing solenoids Inspecting / Replacing Solenoids and Inspecting / replacing solenoids Inspecting / Replacing Solenoids.

Checking the diagnostic trouble codes (DTCs)
Erase and reset the oil counter according to Resetting Transmission fluid change counter.