Attention: When installing the exhaust system parts, make sure that the parts are tightly joined. Otherwise, when measuring the emission of harmful components in the exhaust gases, incorrect results may be obtained.
Self-locking nuts and seals must be replaced with new ones after removal. Retaining rings and rubber buffers must be checked for porosity and damage, defective parts must be replaced with new ones.
When installing a new exhaust system, all mounting parts are also recommended to be replaced with new ones.
Withdrawal
Lift and remove car lower engine cover.
Spray all bolts and nuts of the exhaust system with a rust remover. Leave the agent on the surfaces of the parts for some time to show its effect.
Unbolt bracket at bottom of catalytic converter.
Support the exhaust system with a garage jack and suitable wooden blocks. The supported mass can be from 35 to 45 kg.
Remove front exhaust pipe from exhaust manifold (the figure shows the exhaust system of a gasoline engine) or respectively from the turbocharger.
Unbolt exhaust system from gearbox bracket.
Unscrew hexagon nuts -1- and -2- at bracket for subsequent muffler.
Disconnect the exhaust system from the rubber holders and remove.
Caution: The catalytic converter is sensitive to shock and should not be allowed to fall to the ground.
Installation
Before installing the exhaust system, check that the flange is not distorted in relation to the exhaust manifold, straighten the flange if necessary.
Attention: To make it easier to loosen the nuts and bolts of the exhaust system later, it is recommended to lubricate them with heat-resistant copper grease, for example, Liqui Moly LM-508-ASC or BMW CRC paste.
Install the exhaust system and screw it to the brackets without tightening the mounting bolts too much.
Straighten the exhaust system so that there is a distance of at least 25 mm from the body in all areas. In addition, the end pipe must be evenly spaced from the walls of the body cavity at the rear of the vehicle.
Diesel engine: Screw the front exhaust pipe onto the turbocharger flange. Preliminary check and, if necessary, replace the sealing ring. Apply high temperature copper grease to the O-ring.
Petrol engine: Fit the front exhaust pipe with a new gasket to the exhaust manifold and tighten evenly with new self-locking hexagon nuts. Tighten the fastening bolts to 30 Nm. Then tighten the bolts to 50 Nm in a second step.
Tighten all bolts and nuts firmly. When doing this, tighten the exhaust pipe bracket at the gearbox last so that it is not stressed.
Tightening torques for bolted connections of the exhaust system, Nm:
- exhaust pipe to exhaust manifold - 50;
- joints of triangular flanges - 20;
- exhaust pipe bracket at the gearbox, thread M6 -10; thread M8-20;
- retaining pads - 20;
- after muffler clamp - max. 15.
Install the cross beam and tighten the fastening bolts to 20 Nm.
Start the engine and check the exhaust system for leaks by covering the outlet of the final exhaust pipe with a rag. Have an assistant check all sealing flanges for gas leaks (hissing noise, leakage felt by hand).
Install lower engine cover.
Lower the car.