General Repair Information
General Repair Information
To ensure perfect and successful transmission repairs, the greatest care and cleanliness as well as the use of good and proper tools is essential. 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.
CAUTION!
Before work is done with the engine running, place the selector lever in the "P" position and press the parking brake button to engage the electromechanical parking brake.
Environmental and disposal regulations for oil
Handle the Automatic Transmission Fluid (ATF), axle oil and other oils carefully. Dispose of drained oil properly. Always follow the legal environmental and disposal regulations.
Special Tools and Equipment
For a complete list of special tools used in this repair information, refer to => Workshop equipment and special tools.
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 the "P" position to the "N" position:
• For vehicles through 11.05. Refer to => [ Selector Mechanism Emergency Release ] .
• For vehicles from 11.05. Refer to => [ Selector Mechanism Emergency Release ] Selector Mechanism Emergency Release.
Transmission
• Rules of cleanliness for working on automatic transmissions. Refer to => [ Clean Working Conditions ] Clean Working Conditions.
• Do not run the engine or tow the vehicle with the oil pan removed or when there is no ATF in the transmission.
• Secure the torque converter on removed transmissions to keep it from falling out.
• Thoroughly clean all connections and surrounding areas before disconnecting.
• Check installation dimension of the torque converter before installing the transmission. Refer to Torque Converter, Installing.
• When installing the transmission, make sure that the alignment bushings are fitted correctly.
• Carefully cover or seal the opened components, if repairs are not carried out immediately.
• When replacing the automatic transmission, check the following fluid levels and top off if necessary:
• ATF in planetary gearing, refer to => [ ATF Level Checking and Correcting ] 09LA Automatic Transmission.
• Gear oil in front final drive, refer to => [ Front Final Drive Gear Oil Level Checking ] Front Final Drive Gear Oil Level Checking.
• Gear oil in transfer case, refer to => [ Transfer Case Gear Oil Level Checking ] Transfer Case Gear Oil Level Checking.
• Capacities and specifications, refer to => [ Specifications ] Table of Contents.
• When installing a new rear final drive, check the oil level in the rear final drive and top off if necessary. For capacities and specifications, refer to one of the following:
O-rings, Shaft Seals, Sealing Rings and Seals
• Always replace O-rings, shaft seals, sealing rings and seals after removal.
• After removing the gaskets and seals, always inspect the contact surfaces at the housing or shaft for burrs resulting from removal, or for other signs of damage.
• Before installing a radial shaft seal, fill the space between the sealing lips - arrow - halfway with grease (G 052 128 A1).
• The open side of the shaft seal point toward the fluid to be sealed in.
• Before installing, lightly lubricate the shaft seal outer circumference 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.
• Press in a new shaft seal, so that the sealing lip does not run on the same point as the sealing lip of the old shaft 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 up if necessary. For capacities and specifications, refer to => [ Specifications ] Table of Contents.
Bolts and Nuts
• Loosen bolts in the 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-lubricated nuts and bolts.
• Replace self locking bolts and nuts.
• Clean the threads of bolts that were applied with locking fluid using a wire brush. Then insert the bolts with liquid locking compound.
• Threaded holes into which self locking bolts or bolts coated with locking fluid were installed, must be cleaned (e.g. tap). Otherwise there is a risk that the bolts will shear the next time they are removed.
Fasteners
• Do not over stretch circlips.
• Always replace damaged or overstretched circlips.
• Circlips must seat properly in the groove.
• Replace spring pins. Installation position: Slot is longitudinal to line of force.
Mount
• Install needle bearings with the lettered side (thicker metal) towards fitting tool.
• Insert bearing using axle oil or ATF, depending on installation location.
• Do not interchange the outer or inner races of bearings of the same size.
• Always replace the taper roller bearings on one shaft together and use new bearings from a single manufacturer.
Adjusting Shims
• Use a micrometer to measure the shims at several points. Tolerance variations make it possible to find the exact shim thickness required.
• Check for burrs and damage. Only install perfect shims.
Mechatronic
CAUTION!
• Before touching or removing the mechatronic 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 the connector must not be touched by hand under any circumstances because the control module and the mechatronic can 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 5051B) in the operating modes "Guided Fault Finding", "Vehicle Self-Diagnosis" and "Test Instruments".