Repair Information

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 service information is summarized here. They apply to this repair manual.

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

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

Oil, Environmental and Disposal Regulations

• Handle ATF, transmission fluid (Manual Transmission Fluid) and other oils carefully.

• Dispose of drained ATF properly.

• Do not reuse drained ATF or transmission fluid (Manual Transmission Fluid).

• Follow the legal environmental and disposal regulations.

• Follow the information provided on oil packaging.

Transmission

• Rules for cleanliness when working on the S-Tronic transmission. Refer to => [ Clean Working Conditions ] Clean Working Conditions.

• Do not run engine or tow vehicle with ATF pan removed or without transmission fluid (Manual Transmission Fluid).

• When replacing the transmission, refer to => [ ATF, Checking Level and Correcting ] ATF, Checking Level and Correcting and => [ Transmission Fluid Level, Checking and Filling ] Transmission Fluid Level, Checking and Filling.

• During installation, make sure that the alignment bushings are fitted correctly.

O-rings, Shaft Seals, Seals

• Rules for cleanliness when working on the S-Tronic transmission. Refer to => [ Clean Working Conditions ] Clean Working Conditions.

• O-rings, shaft seals and seals must be replaced.

• After removing gaskets, examine contact surface on the housing/shaft for burr resulting from removal or for other signs of damage.

• Clean the housing separating surface thoroughly before assembling.

• Before installing, lightly lubricate shaft seal outer circumference and sealing lips with ATF or transmission fluid (Manual Transmission Fluid), depending on installation location.

• 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 of the shaft seals point toward the fluid to be sealed in.

• After installing, refer to => [ ATF, Checking Level and Correcting ] ATF, Checking Level and Correcting and => [ Transmission Fluid Level, Checking and Filling ] Transmission Fluid Level, Checking and Filling. Specifications, refer to the Parts Catalog.

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.

• Always replace self-locking nuts and bolts.

• Use a wire brush to clean the threads of bolts that were screwed in with locking compound. Use locking fluid when installing the bolts. Refer to the Parts Catalog.

• Threaded holes into which self-locking bolts or bolts coated with locking fluid are screwed, must be cleaned (for example a tap). Otherwise there is a risk that the bolts will shear 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.

• Lubricate the bearings with transmission fluid (Manual Transmission Fluid) or with ATF, depending on the 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. Different shim thicknesses make it possible to select the required thickness precisely; install two shims if necessary.

• Check for burrs and damage. Only install perfect shims.

Mechatronic

There is a risk of destroying the transmission control module (Mechatronic) with static discharge.

• Always discharge "static electricity" before working with connectors or the Mechatronic. Do this by touching a grounded object, for example vehicle ground, the vehicle or the hoist.

• Do not touch contacts in transmission connector with hands.