General Repair Information
General Repair Information
The maximum possible care, cleanliness and proper tools are essential to ensure satisfactory and successful transmission repairs. The usual basic safety precautions also apply when carrying out vehicle repairs.
Some general repair information that applies to several procedures throughout this service information is summarized here. It applies to this repair information.
Manual release of selector lever
If the battery has been disconnected or is discharged and the vehicle must be towed or pushed, it will be necessary to push the shift mechanism emergency release to shift the selector lever from position "P" to position "N" => [ Selector Mechanism Emergency Release from P Position ] Procedures.
Vehicles with air suspension
Before raising a vehicle with air suspension on a hoist, activate vehicle lift mode.
Transmission
• Rules of cleanliness for working on automatic transmissions => [ Clean Working Conditions ] Clean Working Conditions.
• Do not run engine or tow vehicle with oil pan removed or when there is no ATF in the transmission.
• Secure torque converter on removed transmission to keep it from falling out.
• Thoroughly clean all connections and the surrounding area before disconnecting.
• Check installation dimension of torque converter before installing transmission Torque Converter, Installing.
• When installing transmission, make sure that the alignment bushings are installed correctly.
• Carefully cover over opened components or seal, if repairs are not carried out immediately.
• When replacing the automatic transmission, check the following fluid levels and top up if necessary: ATF in planetary gearing => [ ATF, Checking Level and Correcting ] ATF, Checking Level and Correcting, gear oil in front final drive => [ Gear Oil in Front Final Drive, Filling after Repair ] Gear Oil In Front Final Drive, Filling After Repair, gear oil in transfer case => [ Transfer Case Gear Oil Level, Checking ] Transfer Case Gear Oil Level, Checking. Capacities and specifications => [ Specifications ] Specifications - General, Technical Data.
• When installing a new rear final drive unit, check the oil level in the rear final drive and top off, if necessary.
O-rings, gaskets, seals
• O-rings, gaskets and seals must be replaced.
• After removing gaskets and seals, always inspect the contact surfaces at housing or shaft for burrs resulting from removal, or for other signs of damage.
• Before installing radial shaft seal, fill space between sealing lips - arrow - halfway with grease (G 052 128 A1).
• The open side of the gaskets points toward the fluid to be sealed in.
• Before installing, lightly lubricate outer circumference of seal and sealing lips with ATF or gear oil, depending on installation location.
• Coat O-rings with ATF before inserting to prevent crushing rings during installation.
• Only use ATF for automatic transmission components. Other lubricating substances cause functional problems in the hydraulic transmission control.
• When pressing in new gaskets, make sure the sealing lip does not run on the same point as the sealing lip of the old seal (use insertion depth tolerances).
• Replace paper seals, always clean sealing surfaces and remove old seals completely.
• After installing, check the relevant fluid levels and top off if necessary: ATF in planetary gearing => [ ATF, Checking Level and Correcting ] ATF, Checking Level and Correcting, gear oil in front final drive => [ Gear Oil in Front Final Drive, Filling after Repair ] Gear Oil In Front Final Drive, Filling After Repair, gear oil in transfer case => [ Transfer Case Gear Oil Level, Checking ] Transfer Case Gear Oil Level, Checking, and gear oil in rear final drive.
Bolts and Nuts
• Loosen bolts in reverse order of tightening.
• Tighten and loosen bolts or nuts for securing covers and housings without tightening sequence in diagonal sequence in stages.
• The tightening specifications stated apply to non-oiled nuts and bolts.
• Replace self-locking bolts and nuts.
• Clean threads of bolts that were applied with locking fluid using a wire brush. Then insert bolts with locking fluid (AMV 185 101 A1).
• Threaded holes into which self-locking bolts or bolts coated with locking fluid are installed, must be cleaned (e.g. tap). Otherwise there is a risk that the bolts will shear the next time they are removed.
Circlips
• Do not over-stretch circlips.
• Always replace damaged or over-stretched circlips.
• Circlips must locate properly in the groove.
Mount
• Insert bearing with axle oil or ATF, depending on installation location.
Mechatronic
CAUTION!
• Before touching or removing the Mechatronics unit, you must first discharge yourself of any static electricity by touching (bare handed) some grounded metal object (e.g. car, lifting platform).
• The 16 connector terminals in connector - B - must not be touched by hand under any circumstances because control module and therefore Mechatronic may be destroyed by static discharge.
• Replace the transmission if any of the shift elements are scorched.
• Allocate the Mechatronic to the transmission code.
Guided Fault Finding, OBD and Test Instruments
• Before performing repairs on the automatic transmission, the malfunction cause must be determined as exactly as possible via the Vehicle Diagnostic, Testing and Information System (VAS 5051) in the operating modes "Guided Fault Finding", "Vehicle Self-Diagnosis" and "Test Instruments".