Contents: Four-cylinder petrol engines ↡ SOHC six-cylinder petrol engines ↡ Six-cylinder DOHC petrol engines ↡ Example ↡ Diesel engines ↡
Four-cylinder petrol engines
To determine the required thickness of new main bearings, it is necessary to measure the inner diameter of the main bearing, the diameter of the crankshaft main journal and take into account the bearing operating clearance. The required bearing thickness can be calculated as follows.
Example
Bearing diameter 62.51 mm
Crankshaft journal diameter 57.95 mm
4.56 mm
Bearing working clearance -0.04 mm
4.52 mm ±2
2.26 mm
If it is necessary to use upper and lower main bearing shells of different thicknesses, the thicker shell must be installed in the main bearing cap.
Main bearing shells of the following thicknesses are supplied as spare parts.
| Inserts | Thickness of the liner |
| Nominal | – 2.25 mm |
| Repair size 1 | – 2.37 mm |
| Repair size 2 | – 2.50 mm |
| Repair size 3 | – 2.62 mm |
| Repair size 4 | – 2.75 mm |
SOHC six-cylinder petrol engines
The thickness of the main bearing shells is determined in the same way as for 4-cylinder petrol engines. To determine the required shell size, consult your Mercedes-Benz dealer.
Six-cylinder DOHC petrol engines
To determine the required thickness of new main bearings, it is necessary to measure the inner diameter of the main bearing, the diameter of the crankshaft main journal and take into account the bearing operating clearance. The required bearing thickness can be calculated as follows.
Example
Bearing diameter 62.51 mm
Crankshaft journal diameter 57.95 mm
4.56 mm
Bearing working clearance -0.04 mm
4.52 mm ±2
2.26 mm
If it is necessary to use upper and lower main bearing shells of different thicknesses, the thicker shell must be installed in the main bearing cap.
The required main bearing shell thickness should be determined from the table after consultation with your Mercedes-Benz dealer.
Diesel engines
The main bearing shells are color coded. Three different thicknesses of shells are used, color coded blue, yellow and red.
The engine crankshaft also has color markings applied to the crankshaft cheeks or to the counterweights behind the crankshaft journals. There are also dot markings on the cylinder block.
The thickness of the main bearing shell is selected at the intersection of the vertical and horizontal lines.
| Crankshaft marking color | Markings on the cylinder block | ||
| 1 point | 2 points | 3 points | |
| Blue | Blue | Yellow | Yellow |
| Yellow | Blue | Yellow | Red |
| Red | Yellow | Yellow | Red |
The thickness of the crankshaft main bearing shells can also be determined using the method used for 4-cylinder gasoline engines.
Table for selecting main bearing shells for 6-cylinder DOHC gasoline engines
| Size | Color | Diameter | Thickness of the upper liner | Thickness of the lower liner |
| Nominal | Blue | 58,00 | 2,255 – 2,260 | 2,255 – 2,260 |
| Nominal | Yellow | 58,00 | 2,260 – 2,265 | 2,260 – 2,265 |
| Nominal | Red | 58,00 | 2,265 – 2,270 | 2,265 – 2,270 |
| Nominal increased | White/blue. | 58,00 | – | 2,263 – 2,268 |
| Nominal increased | White/yellow | 58,00 | – | 2,268 – 2,273 |
| Nominal increased | White/red | 58,00 | – | 2,273 – 2,278 |
| Repair 1 | Blue | 57,75 | 2,375 – 2,380 | 2,375 – 2,380 |
| Repair 1 | Yellow | 57,75 | 2,380 – 2,385 | 2,380 – 2,385 |
| Repair 2 | Blue | 57,50 | 2,500 – 2,505 | 2,500 – 2,505 |
| Repair 2 | Yellow | 57,50 | 2,505 – 2,510 | 2,505 – 2,510 |
| Repair 3 | Blue | 57,25 | 2,625 – 2,630 | 2,625 – 2,630 |
| Repair 3 | Yellow | 57,25 | 2,630 – 2,635 | 2,630 – 2,635 |
| Repair 4 | Blue | 57,00 | 2,750 – 2,755 | 2,750 – 2,755 |
| Repair 4 | Yellow | 57,00 | 2,755 – 2,760 | 2,755 – 2,760 |