General Repair Information

Carefulness, cleanliness and the correct tools are required for transmission repairs to be successful. The usual basic safety precautions also, naturally apply when carrying out vehicle repairs.

Some general repair information that applies to several procedures throughout this information is summarized here.

Guided Fault Finding, On Board Diagnostics (OBD) and Test Instruments

• Before servicing the transmission, determine as best as possible the cause of the fault using the Vehicle Diagnostic Tester in the mode Guided Fault Finding  , Vehicle Self-Diagnosis  and Test Instruments  .

Oil, Environmental and Disposal Regulations 

• Handle ATF, axle oil and other fluids with care.
• Dispose of the drained fluids properly.
• Follow the legal environmental and disposal regulations.
• Follow the information provided on oil packaging.

Special Tools and Equipment 

For a complete list of special tools used, refer to Special Tools and Workshop Equipment.

Transmission 

• Follow the rules for clean working conditions when working on the transmission, refer to GUIDELINES FOR CLEAN WORKING CONDITIONS .
• Do not run the engine or tow the vehicle when the center differential housing is removed or when there is no ATF.
• Check the fluid levels after installation and fill if necessary: ATF, refer to ATF LEVEL, CHECKING and gear oil, refer to GEAR OIL . For the correct capacities, refer to CAPACITIES  and specification.

O-Rings, Shaft Seals, Seals 

• O-rings, shaft seals and seals must be replaced.
• After removing gaskets, examine contact surface on housing/shaft for burr resulting from removal or for other signs of damage.
• Clean the housing separating surface thoroughly before assembling.
• To install, thinly coat shaft seals along outer circumference and on sealing lip with ATF.
• Coat O-rings with ATF before inserting to prevent crushing rings during installation.
• Always only use approved ATF. Other types of lubrication cause faults to occur in the transmission hydraulics.
• The open side on the shaft seals faces the fluid to be sealed off.
• Press in 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).
• Check the fluid levels after installation and fill if necessary: ATF, refer to ATF LEVEL, CHECKING and gear oil, refer to GEAR OIL . For the correct capacities, refer to CAPACITIES  and specification.

Bolts and Nuts 

• Loosen the bolts opposite the tightening sequence.
• Nuts and bolts which secure covers and housings should be tightened in steps according to the specified tightening sequence and method.
• Nuts and bolts which secure covers and housings should be loosened and tightened crosswise in stages if no tightening sequence is specified.
• Replace the self-locking nuts and bolts.
• Use a wire brush to clean the threads of bolts that were screwed in with locking compound. Install the bolts with Locking FluidAMV 185 101 A1.
• If self-locking bolts were installed or if regular bolts were installed with locking fluid, then the threaded holes must be cleaned, for example with a thread tap. If the holes are not cleaned, then the bolts could break off the next time they are removed.
• The tightening specifications stated apply to non-oiled nuts and bolts.

Fasteners 

• Do not overstretch the circlips.
• Replace damaged or stretched circlips.
• The circlips must fit completely inside the groove.

Bearings 

• Install needle bearings with lettered side (thicker metal) racing the fitting tool.
• Insert bearing with axle oil or ATF, depending on installation location.
• Do not interchange the outer or inner races for the same size bearings.
• Always replace the tapered roller bearings on one shaft together and use new bearings from a single manufacturer.

Adjusting Shims 

• Measure the adjusting shims at several locations with a micrometer. Tolerance variations make it possible to find the exact shim thickness required.
• Check for burrs and damage. Only install perfect shims.