Catalytic Converter: Service and Repair
Three-way catalytic converter (TWC), replacing
Special tools:
999 5543 Socket NV-22 HO2S 999 5543 Socket NV-22 HO2S
999 5972 Fixture 999 5972 Fixture
951 2050 Bevel Protractor 951 2050 Bevel Protractor
999 7057 Counterhold 999 7057 Counterhold
Removal
Note! As the illustrations in this service information are used for different model years and/or models, some variation may occur. However, the essential information in the illustrations is always correct.
Removing the lower steering shaft joint
- Set the front wheels so that they are straight
- Fold back the floor carpet
- Bend up the outer section of the steering shaft boot
- Remove the retaining clip around the boot
- Pull the boot up
- Turn the steering wheel to gain the best possible access to the steering shaft nut
- Remove the ignition key. Activate the steering wheel lock.
Caution! Do not move the steering wheel. The contact reel in the SRS (supplemental restraint system) could be damaged.
Remove:
- the screw securing the mounting for the steering shaft in the joint
- the joint from the steering shaft by pressing the shaft upwards.
Removing protective plate
- Remove the 6 screws
- Lift up and slide the plate forward
- Remove the splash guard.
Note! There is a guide sleeve on the upper mounting for the plate. This must be lifted slightly so that the panel can be slid forward.
Remove:
- the splash guard under the engine
- the front wheel
- link rod, anti-roll bar and spring strut.
Remove:
- the brake pipe from the clips on the front SIPS member
- the front SIPS member
- the center SIPS (side impact protection system) member and pilot bearing
- the nut between the flange, the three-way catalytic converter (TWC) and exhaust system
- the wiring for the rear heated oxygen sensor (HO2S) from the sub-frame. Separate the wiring.
Marking up and removing the propeller shaft and carrier
Mark the propeller shaft CV joint in relation to the bevel gear flange.
Remove the screws from the propeller shaft. Use counterhold 999 7057 Counterhold 999 7057 Counterhold.
Move the propeller shaft to one side.
Removing the nuts for the bevel gear flange
Mark the position of the flange and nut in relation to the pinion shaft end.
Remove the nut. Use counterhold 999 5652 Counterh 999 5652 Counterh. with adapter 999 5759 Adapter flange All-wheel drive 999 5759 Adapter Flange All-Wheel Drive.
Removing the flange
Remove the flange. Use puller 999 5893 Puller 999 5893 Puller.
Check the seal face on the flange. Replace the flange if it is damaged.
Removing heated oxygen sensors (HO2S)
Remove:
- the engine stabilizer brace between the spring strut stays
- the charge air pipe for the turbocharger (TC) for cylinders 1-3
- the connectors for the front heated oxygen sensors (HO2S). Separate the wiring
- the wiring for the front heated oxygen sensors (HO2S) from the mountings and clips
- The front heated oxygen sensors from the catalytic converter. Use tool 999 5543 Socket NV-22 HO2S 999 5543 Socket NV-22 HO2S.
Caution! Note the location of the heated oxygen sensors (HO2S)
- the heat deflector plates
- the 6 nuts for the flange between the turbocharger (TC) and three-way catalytic converter (TWC).
Hint: Use rust solvent on the studs.
Unhook the three-way catalytic converter (TWC) from the turbocharger (TC).
Removing the charge air pipe
Remove:
- the charge air pipe on the intake between the throttle module and the charge air cooler.
Hint: If necessary use a hot air gun to loosen the pipe
- undo the hose clamp on the charge air pipe at the fuel rail. Separate the hose and pipe.
Place the servo reservoir and the expansion tank on the engine.
Note! Ensure that no oil leaks out of the reservoir through the ventilation holes in the cover.
Lowering the engine and transmission unit
Caution! Ensure that the lifting table is properly centered under the engine.
Position a lifting table under the sub-frame. Secure the table against the sub-frame
Remove:
- the screws at the rear of the brackets for the sub-frame
- the screws for the sub-frame. Lower the engine and transmission approximately 10 cm so that the drive shafts describe a horizontal line between the hub and transmission
- the three-way catalytic converter (TWC). If necessary, carefully lower the engine slightly at the rear to lower the three-way catalytic converter (TWC).
Transfer the rear heated oxygen sensor (HO2S).
Use tool 999 5543 Socket NV-22 HO2S 999 5543 Socket NV-22 HO2S.
Tighten to 45 Nm.
Installation
Note! For tightening torques, see: Tightening torque, B6324S Tightening Torque.
Note! To ensure that there is no exhaust leakage, see: Flanged joint, assembling Flanged Joint, Assembling.
Installing components
Warning! Avoid skin contact with the copper paste.
- Lubricate the studs on the turbocharger (TC). Use copper paste 116 1408.
- Lift the three-way catalytic converter (TWC) up into position
- Install the three-way catalytic converter (TWC) against the exhaust system. Use a new gasket. Install new nuts but do not tighten.
- Lift the sub-frame until it is against the frame members
- Install new screws in the sub-frame. Lubricate the screw threads. Install the washers in the front edge and support plates at the rear edge of the sub-frame
- First tighten the screws on the left side of the subframe. See Tightening torque, B6324S Tightening Torque. Use bevel protractor 951 2050 Bevel Protractor 951 2050 Bevel Protractor. Then tighten the screws on the right-hand side of the subframe to the same value.
- Tighten the brackets. Tighten to 50 Nm.
- Remove the lifting table.
Install:
- the servo reservoir
- the expansion tank
- the charge air pipe between the throttle module and charge air cooler
- the hose on the charge air pipe at the top of the engine.
Installing the three-way catalytic converter (TWC)
Pull up and align the three-way catalytic converter (TWC) against the turbocharger (TC).
Tighten the three-way catalytic converter (TWC) to the turbocharger (TC). Use new nuts. Torque tighten. See Tightening torque, B6324S Tightening Torque.
Install:
- the upper heated oxygen sensors (HO2S) according to the marks made after removal. Lubricate the threads using copper paste 116 1408. Tighten to 45 Nm.
- lower the wiring down for the heated oxygen sensors (HO2S). Secure the wiring in the clips and clamps. Connect the wiring
- the heat deflector plates
- the charge air pipe for the turbocharger (TC) for cylinders 1-3
- the engine stabilizer brace between the spring strut turrets.
Installing the flange on the pinion
Install the carrier using the marks made earlier. If necessary, use tool 999 5504 PRESS TOOL, DRIVE FLANGE 999 5504 Press Tool, Drive Flange.
Installing a new nut in the carrier
Install a new lubricated nut.
Note! There must be no axial play.
Tighten to 180-200 Nm. Use counterhold 999 5652 Counterh. 999 5652 Counterh. with adapter 999 5759 Adapter flange All-wheel drive 999 5759 Adapter Flange All-Wheel Drive.
Note! 200 Nm must not be exceeded
The forces on the pinion bearing may become too great, causing it to seize.
Installing the propeller shaft
Check that the mating surfaces on the propeller shaft CV joint and flange are clean.
Align the propeller shaft CV joint against the flange.
Install the screws loosely in the support for the center bearing and the propeller shaft.
Installing the propeller shaft using the marks made earlier
Use new screws. First tighten the screws crosswise. Tighten to 8 Nm. Then tighten to 30 Nm.
Use counterhold 999 7057 Counterhold 999 7057 Counterhold.
Tighten the screws for the support for the center bearing.
Tighten the screws for the propeller shaft center bearing
Installing components
- Install the front SIPS member. Press the brake pipe into place in the member
- Hook the rubber mounting for the three-way catalytic converter (TWC) in the bracket on the sub-frame
- Connect the connector for the rear heated oxygen sensors (HO2S). Clamp the wiring. Tighten the screwed joint between the three-way catalytic converter (TWC) and the exhaust system. See Tightening torque, B6324S Tightening Torque.
Finishing
Install:
- the anti-roll bar links. Use new lock nuts
- the splash guard under the engine
- the front protective cover on the sub-frame
- the front wheels. See Installing wheels Service and Repair
Installing steering shaft joint
Install:
- the steering shaft joint on the steering gear and steering shaft
- new screw
- the steering shaft boot and snap ring. Fold back the carpet.
Check for leakage.