The chain tension is regulated by a hydraulic tensioner with lock.
Aluminum alloy camshaft drive cover.
Valve timing
The calculation of the valve timing is given for a zero calculated valve clearance and a valve lift height of 2 mm.
The value in brackets is after a run of 20,000 km.
Parameter, mm | Engine model | |||
M 115.938 | M 102.920, M 102.939 | M 102.980, M 102.982 | M 115.954 | |
| Start of opening of the intake valve before TDC of the intake stroke with advance | 14,0 | 11,0 (12,0) | 11,0 (12,0) | 14,0 |
| Closing of the intake valve after BDC of the compression stroke with a delay | 20,0 | 17,0 (18,0) | 17,0 (18,0) | 27,0 |
| Start of opening of the exhaust valve before the BDC of the working stroke with advance | 22,0 | 32,0 (31,0) | 32,0 (31,0) | 36,5 |
| Closing of the exhaust valve after TDC of the exhaust stroke with a delay | 12,0 | 13,0 (12,0) | 13,0 (12,0) | 18,50 |
| Camshaft marking | 5 | 12 | 23 | 13 |
Parameter, mm | M 123.920, M 123.921 | M 110.923 | M 110.984, M 110.988 | |
| Start of opening of the intake valve before TDC of the intake stroke with advance | 15,0 | 7,0 | 7,0 | |
| Closing of the intake valve after BDC of the compression stroke with a delay | 21,0 | 21,0 | 21,0 | |
| Start of opening of the exhaust valve before the BDC of the working stroke with advance | 21,0 | 30,0 | 30,0 | |
| Closing of the exhaust valve after TDC of the exhaust stroke with a delay | 11,0 | 12,0 | 12,0 | |
| Camshaft marking | 02 | right: 57 | 71 | |
Camshafts
Five- (engines M 102 and M 115) or semi-supportive (engines M 110 and M 123) hollow camshaft. The front end of the shaft is closed by a sprocket mounting bolt, and the rear end is closed by a steel plug. Oil enters the shaft channel through a groove and a hole in the rear support and provides lubrication of the support shaft. A digital mark is stamped on the end of the sprocket mounting flange on the shaft.
Characteristics of camshafts
The stretching of the timing chain can be compensated by moving the camshaft sprocket.
Characteristic | Meaning |
| Permissible radial runout of camshaft journals, mm | 0,025—0,030 |
| Surface cleanliness of camshaft bearing support, µm | 0,003 |
Camshaft sprocket offset, mm | Amendment |
0,7 | 6° |
0,9 | 8° |
| 1,1 | 9,5° |
| 1,3 | 11,5° |
The clearances in the valve drive mechanism on a cold and hot engine for the intake and exhaust valves are given in the table. On engines with hydraulic compensation of the clearance in the valve drive, the valve clearances are not adjusted.
Bearing supports are not heat treated. The 1st support of the M 110 engine is not ground, a bushing is installed on it.
Parameter, mm | Engine model | |||
M 115.938 | M 102.920, M 102.939 | M 102.980, M 102.982 | M 115.954 | |
On a cold engine | ||||
| 0,10 | 0,15 | 0,15 | 0,10 |
| 0,20 | 0,20 | 0,20 | 0,20 |
On a warm engine (oil temperature 45-75°C) | ||||
| 0,15 | 0,30 | 0,30 | 0,15 |
Parameter, mm | M 123.920, M 123.921 | M 110.923 | M 110.984, M 110.988 | |
On a cold engine | ||||
| 0,10 | 0,10 | 0,10 | |
| 0,20 | 0,25 | 0,25 | |
On a warm engine (oil temperature 45-75°C) | ||||
| 0,15 | 0,15 | 0,15 | |
Characteristics of camshafts
Parameter, mm | Engine model | |||
M 115.938 | M 102.920, M 102.939 | M 102.980, M 102.982 | M 115.954 | |
| Support 1 | ||||
Shaft journal diameter | ||||
| 34,959—34,975 | 31,934—31,950 | 34,959—34,975 | |
| 34,859—34,875 | * | 34,859—34,875 | |
| 34,709—34,725 | 32,434—32,450 | 34,709—34,725 | |
Support hole diameter | ||||
| 35,000—35,016 | 32,000—32,025 | 35,000—35,016 | |
| 34,900—34,916 | * | 34,900—34,916 | |
| 34,750—34,766 | 32,500—32,525 | 34,750—34,766 | |
| Supports 2 and 3 | ||||
Shaft journal diameter | ||||
| 48,959—48,975 | — | — | 48,959—48,975 |
| 48,859—48,875 | — | — | 48,859—48,875 |
| 48,709—48,725 | — | — | 48,709—48,725 |
Support hole diameter | ||||
| 49,000—49,016 | — | — | 49,000—49,016 |
| 48,900—48,916 | — | — | 48,900—48,916 |
| 48,750—48,766 | — | — | 48,750—48,766 |
| Support 4 | ||||
Shaft journal diameter | ||||
| — | — | — | — |
| — | — | — | — |
| — | — | — | — |
Support hole diameter | ||||
| — | — | — | — |
| — | — | — | — |
| — | — | — | — |
| Support 5 | ||||
Shaft journal diameter | ||||
| — | — | — | — |
| — | — | — | — |
| — | — | — | — |
Support hole diameter | ||||
| — | — | — | — |
| — | — | — | — |
| — | — | — | — |
| Support 6 | ||||
Shaft journal diameter | ||||
| — | — | — | — |
| — | — | — | — |
| — | — | — | — |
Support hole diameter | ||||
| — | — | — | — |
| — | — | — | — |
| — | — | — | — |
| Support 7 | ||||
Shaft journal diameter | ||||
| — | — | — | — |
| — | — | — | — |
| — | — | — | — |
Support hole diameter | ||||
| — | — | — | — |
| — | — | — | — |
| — | — | — | — |
Parameter, mm | M 123.920, M 123.921 | M 110.923 | M 110.984, M 110.988 | |
| Support 1 | ||||
Shaft journal diameter | ||||
| 34,93—34,95 | 23,98—23,99 | ||
| 34,83—34,85 | * | ||
| 34,68—34,70 | * | ||
Support hole diameter | ||||
| 35,00—35,02 | 38,00—38,02* | ||
| 34,90—34,92 | * | ||
| 34,75—34,77 | * | ||
| Supports 2 and 3 | ||||
Shaft journal diameter | ||||
| 48,93—48,95 | 49,93—49,94 | ||
| 48,83—48,85 | 49,68—49,70 | ||
| 48,68—48,70 | 49,43—49,45 | ||
Support hole diameter | ||||
| 49,00—49,02 | 50,05—50,07 | ||
| 48,90—48,92 | 49,80—49,82 | ||
| 48,75—48,77 | 49,55—49,57 | ||
| Support 4 | ||||
Shaft journal diameter | ||||
| 49,93—49,95 | 49,93—49,95 | ||
| 49,83—49,85 | 49,68—49,70 | ||
| 49,69—49,70 | 49,43—49,45 | ||
Support hole diameter | ||||
| 50,00—50,02 | 50,00—50,02 | ||
| 49,90—49,92 | 49,75—49,77 | ||
| 49,75—49,77 | 49,50—49,52 | ||
| Support 5 | ||||
Shaft journal diameter | ||||
| — | 51,42—51,44 | ||
| — | 51,17—51,19 | ||
| — | 50,92—50,94 | ||
Support hole diameter | ||||
| — | 51,50—51,52 | ||
| — | 51,25—51,27 | ||
| — | 51,00—51,02 | ||
| Support 6 | ||||
Shaft journal diameter | ||||
| — | 52,92—52,94 | ||
| — | 52,67—52,69 | ||
| — | 52,47—52,49 | ||
Support hole diameter | ||||
| — | 53,00—53,02 | ||
| — | 52,75—52,77 | ||
| — | 52,50—52,52 | ||
| Support 7 | ||||
Shaft journal diameter | ||||
| — | 53,92—53,94 | ||
| — | 53,67—53,69 | ||
| — | 53,43—53,45 | ||
Support hole diameter | ||||
| — | 54,00—54,02 | ||
| — | 53,75—53,77 | ||
| — | 53,50—53,52 | ||
* The 1st support bushing has an outer diameter of 37.93–37.95 mm and an inner diameter of 24.00–24.01 mm.
Hydraulic tensioner
The pusher piston, under the action of oil pressure in the engine lubrication system and the internal spring, constantly acts on the tensioner shoe.
Characteristic | Meaning |
| Oil feed hole diameter, mm | 1,1 |
| Oil outlet diameter, mm | 1,2 |