Service information: Exhaust valve

Modification notes

As part of ongoing technical development, the modified cylinder heads are installed on the above-mentioned engines.

The changes affect the following components:

 Exhaust valve:
Valve seat angle
(without code (MS8) Natural gas engine changed from
45° to 36°)
(with code (MS8) Natural gas engine changed from
20° to 36°)
Valve seat width
valve stem

 Exhaust valve seat ring:
Material and valve seat angle
(without code (MS8) Natural gas engine changed from
45° to 36°)
(with code (MS8) Natural gas engine changed from
20° to 36°)

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 Exhaust valve spring:
height

A differentiation can be detected on the new and old components in the following manner:

 Exhaust valve
based on the stem which increases in size downwards

 Exhaust valve seat ring:
Can only be differentiated through variant parts list (SAA), as a visual difference is not apparent

 Exhaust valve spring
based on color code and the height.

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In a repair instance, the modified cylinder head can be installed in all the engines (Euro 0 to Euro 5).

In the event of any damage to Euro 4 or Euro 5 engines with a driven distance of less than 250,000 km, or for Unimog and industrial engines within the 2-year warranty, we advise installing a modified, new cylinder head.

The replacement of the previous components (exhaust valve 20° or 45°, valve seat ring 20° or 45°, valve spring) is also possible, insofar as the required parts for the engine are filed in the EPC.

A conversion of the cylinder head to the new components (exhaust valve 36°, valve seat ring 36°, valve spring) as a package solution, i.e. all cylinder head exhaust valves, is also possible.

 A mixed installation of the components 20° or 45° and 36° is not permissible, because this will result in damage to the engine.

 The variant parts list (SAA) documentation is to be correspondingly updated in the VeDoc according to the following table (overview of cylinder head conversion from 20° or 45° to 36°) when converting to 36°.

The vehicle or engine data in VeDoc must be modified in line with this table.

Overview of cylinder head conversion from 20° or 45° to 36°