Exhaust Manifold: Service and Repair
WM 261019 Removing and installing exhaust manifold
Preliminary work
Preliminary work for removing and installing exhaust manifold
1. Remove engine. -> 100119 Removing and installing engine - section on "Removing" 100119 Removing and installing engine
2. Naturally aspirated engines only:
Remove primary catalytic converters. -> 267619 Removing and installing primary catalytic converter - section on "Removing" 267619 Removing and installing primary catalytic converter
Removing exhaust manifold
Removing exhaust manifold for cylinder bank 1 - 4
Information
- The pictures shown in this document may differ from the original.
- However, this does not affect the validity and relevance of the pictures.
Information
On turbo engines, there is no need to remove the primary catalytic converter and turbocharger when removing the exhaust manifold.
1. Remove heat shields on the exhaust manifold for cylinder bank 1 - 4 and on the generator. -arrows-
Heat shields for cylinders 1 - 4
2. Remove heat shield on exhaust manifold for cylinders 5 - 8.
Heat shield for cylinders 5 - 8
2.1. Loosen fastening screws -1- on the heat shield.
2.2. Unclip heat shield -2- from the holders -3-.
3. Unclip the oxygen sensor cable from all holders. Remove oxygen sensor when replacing the exhaust manifold. Cylinders 1 to 4 => Oxygen sensor on naturally aspirated engine, cylinders 1 to 4.
Oxygen sensor on naturally aspirated engine, cylinders 1 to 4
4. Spray fastening nuts on the exhaust manifold with anti-rust agent if necessary.
5. Loosen the fastening nuts in reverse order to the sequence shown below => Tightening sequence for exhaust manifold on naturally aspirated engine, cylinders 1 to 4. Remove exhaust manifold. Replace fastening nuts.
Tightening sequence for exhaust manifold on naturally aspirated engine, cylinders 1 to 4
6. Only for vehicles with turbocharger:
Loosen fastening screws -4- for the turbocharger.
The turbocharger and the primary catalytic converters must not be removed.
7. Only for vehicles with turbocharger:
Loosen the fastening nuts on the exhaust manifold in reverse order to the sequence shown and remove them => Tightening sequence for exhaust manifold on turbo engine, cylinders 1 to 4. Remove exhaust manifold. Replace nuts.
Tightening sequence for exhaust manifold on turbo engine, cylinders 1 to 4
8. Remove the seal and replace it. Clean sealing faces. Cylinders 1 to 4 => Exhaust manifold on naturally aspirated engine, cylinders 1 to 4.
Exhaust manifold on naturally aspirated engine, cylinders 1 to 4
9. Only for vehicles with turbocharger:
Remove seal and replace it. Clean sealing faces. Cylinders 1 to 4 => Exhaust manifold on turbo engine, cylinders 1 to 4.
Exhaust manifold on turbo engine, cylinders 1 to 4
Removing exhaust manifold for cylinder bank 5 - 8
Information
- The pictures shown in this document may differ from the original.
- However, this does not affect the validity and relevance of the pictures.
Information
On turbo engines, there is no need to remove the primary catalytic converter and turbocharger when removing the exhaust manifold.
1. Unclip the oxygen sensor cable from all holders. Remove oxygen sensor when replacing exhaust manifold. Cylinders 5 to 8 => Oxygen sensor on naturally aspirated engine, cylinders 5 to 8.
Oxygen sensor on naturally aspirated engine, cylinders 5 to 8
2. Spray fastening nuts on the exhaust manifold with anti-rust agent if necessary.
3. Loosen the fastening nuts in reverse order to the sequence shown below => Tightening sequence for exhaust manifold on naturally aspirated engines, cylinders 1 to 4 (identical to cylinders 5 to 8). Remove exhaust manifold. Replace fastening nuts.
Tightening sequence for exhaust manifold on naturally aspirated engines, cylinders 1 to 4 (identical to cylinders 5 to 8)
4. Only for vehicles with turbocharger:
Loosen fastening screws -3- for the turbocharger.
The turbocharger and the primary catalytic converters must not be removed.
5. Only for vehicles with turbocharger:
Loosen the fastening nuts on the exhaust manifold in reverse order to the sequence shown and remove them => Tightening sequence for exhaust manifold on turbo engines, cylinders 1 to 4 (identical to cylinders 5 to 8). Remove exhaust manifold. Replace nuts.
Tightening sequence for exhaust manifold on turbo engines, cylinders 1 to 4 (identical to cylinders 5 to 8)
6. Remove the seal and replace it. Clean sealing faces. Cylinders 5 to 8 => Exhaust manifold on naturally aspirated engine, cylinders 5 to 8.
Exhaust manifold on naturally aspirated engine, cylinders 5 to 8
7. Only for vehicles with turbocharger:
Remove the seal and replace it. Clean sealing faces. Cylinders 5 to 8 => Exhaust manifold on turbo engine, cylinders 5 to 8.
Exhaust manifold on turbo engine, cylinders 5 to 8
Installing exhaust manifold
Installing exhaust manifold for cylinder bank 1 - 4
Information
- Visually inspect exhaust manifold for cracks and distortion.
- A cracked or distorted exhaust manifold must not be reinstalled.
- As a matter of principle, replace seals on manifold.
- Replace the studs in the cylinder head if damaged. Measure the studs with respect to the cylinder head and fit new studs to the same screw-in depth as the old studs.
Information
- The tightening specifications for the basic engine are stored centrally. -> 1001IN Tightening torques, tightening sequences, assembly overviews [1][2]Specifications. Tightening torques and assembly instructions for other assemblies (e.g. chassis, electrics, transmission or body) or for peripheral engine equipment can be found in the corresponding documents.
1. Clean sealing surfaces. The surfaces must be free from foreign objects.
2. Fit oxygen sensor when replacing the exhaust manifold (grease the thread of the oxygen sensor with a light coating of grease 000.043.207.07, status 06/07).
3. Use a new seal. The seal must be positioned so that the part number is visible from the outside.
Exhaust manifold on naturally aspirated engine, cylinders 1 to 4
4. Slide the exhaust manifold over the studs and fit it using new fastening nuts. The fastening nuts will be tightened to the prescribed tightening torque. Observe tightening sequence.
Tightening sequence for exhaust manifold on naturally aspirated engine, cylinders 1 to 4
5. Only for vehicles with turbocharger:
Use a new seal (the seal for the turbocharger is also replaced). The exhaust manifold seal must be positioned so that the part number is visible from the outside.
Exhaust manifold on turbo engine, cylinders 1 to 4
6. Only for vehicles with turbocharger:
Slide the exhaust manifold over the studs and fit it using new fastening nuts. The fastening nuts will be tightened to the prescribed tightening torque. Observe tightening sequence.
Tightening sequence for exhaust manifold on turbo engine, cylinders 1 to 4
7. Fit fastening screws for the turbocharger.
8. Clip oxygen sensor cable into the holders. => Oxygen sensor on naturally aspirated engine, cylinders 1 to 4
Oxygen sensor on naturally aspirated engine, cylinders 1 to 4
9. Fit heat shields. => Heat shields on V8 naturally aspirated engine
Heat shields on V8 naturally aspirated engine
10. Fit heat shield for cylinder bank 5 - 8.
Heat shield for cylinders 5 - 8
10.1. Clip heat shield -2- into the holders -3-.
10.2. Fit the fastening screws -1- for the heat shield.
Installing exhaust manifold for cylinder bank 5 - 8
Information
- Visually inspect exhaust manifold for cracks and distortion.
- A cracked or distorted exhaust manifold must not be reinstalled.
- As a matter of principle, replace seals on manifold.
- Replace the studs in the cylinder head if damaged. Measure the studs with respect to the cylinder head and fit new studs to the same screw-in depth as the old studs.
Information
- The tightening specifications for the basic engine are stored centrally. -> 1001IN Tightening torques, tightening sequences, assembly overviews [1][2]Specifications. Tightening torques and assembly instructions for other assemblies (e.g. chassis, electrics, transmission or body) or for peripheral engine equipment can be found in the corresponding documents.
1. Clean sealing surfaces. The surfaces must be free from foreign objects.
2. Fit oxygen sensor when replacing the exhaust manifold (grease the thread of the oxygen sensor with a light coating of grease 000.043.207.07, status 06/07).
3. Use a new seal. The seal must be positioned so that the part number is visible from the outside.
Exhaust manifold on naturally aspirated engine, cylinders 5 to 8
4. Slide the exhaust manifold over the studs and fit it using new fastening nuts. The fastening nuts will be tightened to the prescribed tightening torque. Observe tightening sequence.
Tightening sequence for exhaust manifold on naturally aspirated engines, cylinders 1 to 4 (identical to cylinders 5 to 8)
5. Only for vehicles with turbocharger:
Use a new seal (the seal for the turbocharger is also replaced). The exhaust manifold seal must be positioned so that the part number is visible from the outside.
Exhaust manifold on turbo engine, cylinders 5 to 8
6. Only for vehicles with turbocharger:
Slide the exhaust manifold over the studs and fit it using new fastening nuts. The fastening nuts will be tightened to the prescribed tightening torque. Observe tightening sequence.
Tightening sequence for exhaust manifold on turbo engines, cylinders 1 to 4 (identical to cylinders 5 to 8)
7. Fit fastening screws for the turbocharger.
8. Clip oxygen sensor cable into the holders. => Oxygen sensor on naturally aspirated engine, cylinders 5 to 8
Oxygen sensor on naturally aspirated engine, cylinders 5 to 8
Subsequent work
Subsequent work for removing and installing exhaust manifold
1. Naturally aspirated engines only:
Fit primary catalytic converters. -> 267619 Removing and installing primary catalytic converter - section on "Installing" 267619 Removing and installing primary catalytic converter
2. Install engine. -> 100119 Removing and installing engine - section on "Installing" 100119 Removing and installing engine