Selecting new inserts
Four cylinder petrol engines
1. To determine the thickness of the required liners, the diameter of the shaft journals and the working clearance in the bearings should be determined. The required thickness can be calculated as shown in the example given.
2. If it is determined that upper and lower bearing shells of different thicknesses are required, the thicker shell should always be installed on the bearing cap.
3. Mercedes-Benz dealers or engine repair specialists will be able to supply bearings of the required thickness. Refer to the following table to see which bearings are available.
Six cylinder petrol engines
4. The thickness of the required liners can be determined in the same way as described earlier for 4-cylinder petrol engines. At the time of writing, there was no information on the liners produced for 6-cylinder petrol engines. You can consult with Mercedes-Benz dealers. You can also buy liners from them.
Diesel engines
5. The inserts are color coded. There are three thicknesses of inserts, designated by blue, yellow and red colors.
6. Color marking is applied to the crankshaft or to the shaft cheeks or to the counterweights following the journals. Marks are also applied to the cylinder block - they have the form of depressions on the contact surface with the pallet, behind the location of the bearings.
7. To limit the need to measure the operating clearance in bearings, select the required bearing insert according to the table provided.
Crankshaft color code
Potholes on the cylinder block
8 You can determine the thickness of the bearing shells using the method described for the 4-cylinder petrol engine. Refer to the table in item 3 to determine which bearing shells are available.
Checking the working clearance in the main bearings
9. The working clearance can be determined using the "native" liners. However, it is preferable to use a new set, since the results obtained will be more reliable.
10. Clean the back side of the liners and the seating areas on the cylinder block and main bearing caps.
11. Install the bearing shells in their places, making sure that the bearing shell projection fits into the recess in the cylinder block or bearing cap. Do not touch the surface of the bearing shells with your fingers. Note that the bearing shells with a groove are installed on the cylinder block, and the flat bearing shells are installed in the caps. If the "native" bearing shells are used for the check, make sure that they are installed in their places.
Fig. 19.11. Make sure that the liner protrusion (shown by arrow) is installed in a recess on the lid
12. The gap can be checked in two ways.
13. One method (which is difficult to do without using an inside diameter micrometer or calipers) is to measure the inside diameter of each assembled pair of bearings with the bearing shells installed and the main bearing caps properly tightened. The bearing running clearance is defined as the difference between the bearing inside diameter and the main journal outside diameter.
14. Second (and more accurate) the method consists of using a plastic indicator ("Rastigauge"). The indicator is a thin plastic thread of a perfectly round shape, which is pressed between the main bearing and the journal. When the liners are removed, using a special template attached to the kit, you can determine the working clearance by the width of the pressed plastic strip. "Plastigauge" can be purchased from a Peugeot dealer (or order a similar product under a different name). The method is as follows.
15. Install the upper bearings in the bed and carefully install the crankshaft on them. Do not use grease; the crankshaft journals and bearings must be completely clean and dry.
16. Cut several pieces of Plastigage thread to the appropriate length (slightly shorter than the width of the inserts) and place one piece of thread along the axis on each main journal of the crankshaft (see fig. 19.16)
Fig. 19.16. Plastigauge thread on the crankshaft main journal
17. Insert the bearing shell into the bearing cap and install the cap in place, tightening it with the bolts. Starting from the middle bearing and moving towards the periphery, tighten the bearing cap bolts gradually to the required torque. Do not move the Plastigauge thread or turn the crankshaft during this procedure.
18. Remove the bearing cap, again be careful not to move the Plastigauge thread or turn the crankshaft. Again, be careful not to move the Plastigauge thread or turn the crankshaft. If any of the caps are difficult to remove, tap them with a wooden mallet.
19. To determine the working clearance in the bearing, compare the width of the Plastigauge strip on the journal with the scale on the template (see fig. 19.19). Compare the result obtained with the "Technical data" at the beginning of this chapter.
Fig. 19.19. Determining the thickness of the deformed Plastigauge thread using a template
20. If the clearances are significantly different from what you expected, this means that the bearing size is incorrect (or the bearings are badly worn if the original bearings are used). Before changing the bearing size, make sure that no oil, dust, etc. has gotten between the bearings. If the Plastigauge strip is not the same thickness, this may indicate that the main journal is tapered.
21. If the clearance does not meet the technical requirements, determine the group of liners you need. When determining the required clearance, keep in mind that it is always better to get a clearance closer to the lower limit of the permissible range.
22. If necessary, purchase liners of the correct size and repeat the running clearance check as described above.
23. After measuring, scrape off any traces of Plastigauge with your fingernail or a wooden or plastic scraper.
Final installation of the crankshaft
Note: It is strongly recommended that new main bearing cap bolts be used when making final crankshaft installation. Sealant may be required when installing the rear crankshaft oil seal housing.
24. Carefully remove the crankshaft from the cylinder block.
25. Where installed, check that the oil spray tube nozzles are installed in the location of the bearings in the cylinder block.
26. Place the bearings in their places as described earlier. When installing new bearings, wash off all traces of kerosene preservation from them. Wipe the bearings dry with a lint-free cloth. Generously lubricate each bearing in the cylinder block with fresh engine oil.
27. Similarly, install the upper half rings on the corresponding bearing.
- a) 4-cylinder engines - middle (No. 3) main bearing
- b) 5-cylinder engine - No.4 main bearing
- c) 6-cylinder engines - No.5 main bearing
Make sure that all oil grooves in the thrust washers are facing towards the crankshaft journals.
28. Install the crankshaft in place.
29. Lubricate the lower shells in the main bearing caps with clean engine oil. Check that the protrusions in the shells fit into the grooves in the caps.
30. Install the main bearing caps in their places, making sure that they are correctly oriented. Check that the thrust washers are installed on the corresponding bearings (see item 27) (see Fig. 19.30, a, b).
Fig. 19.30, a. Installing the thrust half ring on the main bearing cap (apply a little grease to hold the half ring on the lid)
Fig. 19.30, b. Installing the main bearing cap
31. Lightly lubricate the bolt threads, then fit the cover bolts, using new bolts if possible (see paragraph 16 - it is strongly recommended that new bolts be used on all engines). Where provided, check that the oil pick-up tube bracket is in place on the appropriate bolt as recorded prior to removal. At this stage, tighten the bolts finger tight.
32. Gradually tighten the bearing cap bolts to the specified torque, starting with the middle bearing cap and working outwards. Where specified, observe the tightening steps given in the Technical Data section (see fig. 19.32, a, b). When tightening bolts to a certain angle, it is recommended to use an angle measuring device to improve the tightening accuracy. If there is no angle measuring device, apply alignment marks with white paint to the bolt and cover, they will allow you to determine the angle to which the bolts were tightened.
Fig. 19.32, a. Tighten the main bearing cap bolts to the required tightening torque...
Fig. 19.32, b....then turn to the required angle
33. Check that the crankshaft turns freely.
(Material taken from a web resource: mercedesman.ru)
34. Install a new rear crankshaft oil seal into the housing, then install the housing using a new gasket or sealant (see Fig. 19.34, a, b).
Fig. 19.34, a. Apply sealant to the rear cuff housing
Fig. 19.34, b. Tighten the crankshaft rear oil seal housing bolts to the required torque
35. Install the connecting rods with pistons as an assembly as described in paragraph 20.
36. Depending on the engine type, do the following:.
- a) On 4-cylinder petrol engines, where provided, install the crankshaft sprocket, then install the chain, chain guard, pan and flywheel/drive plate as described in part A of this Chapter.
- b) On 6-cylinder petrol engines, where required, fit the crankshaft sprocket, then fit the chain, lower chain case, sump and flywheel/drive faceplate as described in part B of this Chapter.
- c) On diesel engines, where required, install the crankshaft sprocket, then install the chain, chain cover, oil pump, oil deflector plate (where provided), the pan and the flywheel/drive faceplate as described in parts of this Chapter.