Four-cylinder petrol engines
To determine the required thickness of new main bearings, it is necessary to measure the internal diameter of the main bearing, the diameter of the crankshaft main journal, and take into account the operating clearance of the bearing. 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 bearings of different thicknesses, then the thicker bearing must be installed in the main bearing cap.
Main bearing shells are available as spare parts in the following thicknesses.
| Inserts | Liner thickness |
| 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 |
Six-cylinder SOHC gasoline engines
The thickness of the main bearing shells is determined in the same way as for 4-cylinder petrol engines. Consult your Mercedes-Benz dealer to determine the required bearing size.
Six-cylinder DOHC gasoline engines
To determine the required thickness of new main bearings, it is necessary to measure the internal diameter of the main bearing, the diameter of the crankshaft main journal, and take into account the operating clearance of the bearing. 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
2.26mm
If it is necessary to use upper and lower main bearings of different thicknesses, then the thicker bearing must be installed in the main bearing cap.
Determine the required main bearing shell thickness from the table after consulting your Mercedes-Benz dealer.
Diesel engines
The main bearing shells are color coded. Available in three different thicknesses, color-coded blue, yellow and red.
The engine crankshaft is also color coded on the crankshaft webs or counterweights behind the crankshaft journals. There are also marks in the form of dots 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 | Labels on the cylinder block | ||
| 1 point | 2 points | 3 points | |
| Blue | Blue | Yellow | Yellow |
| Yellow | Blue | Yellow | Red |
| Red | Yellow | Yellow | Red |
Also, the thickness of the crankshaft main bearing shells can be determined by the method used for 4-cylinder gasoline engines.
Chart for selecting main bearing shells for 6-cylinder DOHC gasoline engines
| Size | Color | Diameter | Top liner thickness | Bottom liner thickness |
| 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 |
| Rated increased | White/blue | 58,00 | – | 2,263 – 2,268 |
| Rated increased | white/yellow | 58,00 | – | 2,268 – 2,273 |
| Rated 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 |