Accumulator Piston/Sealing Ring B2/C2, Replacing

Accumulator piston/sealing ring B2/C2, 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.

Replacing accumulator piston and sealing rings B2/C2




Remove:

- The cover plate with gasket. Check that the gasket is free from fault.
- Control valve, accumulators with springs (1)
- Springs and modulator valve B2 (2)
- Springs and modulator valve C2 (3)
- Accumulator piston C2 with 2 springs (C2).
- Accumulator piston B2 with 2 springs (B2). (Note! Outer spring secured in the piston.)

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.

Spring data for the accumulator pistons and valves
Engine B5202S, B5204S,B5254S, B5252S, B5234S





*) Spring data applies to the inner springs
Engine B5234 T





*) Spring data applies to the inner springs

Replace the sealing rings on the accumulator pistons.




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

Install the accumulator pistons with springs




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

Caution! 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.

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