Mounting crankshaft in bearings - RA03001203200X(03-3200)

Preceding work:

Engine removed and disassembled.

Oil passages in crankcase and in crankshaft cleaned.

Crankshaft inspected for cracks, dimensional tolerance, hardness and concentricity.

Engine 120.980/981 

Fig 1: Identifying Crankshaft, Belt Pulley And Ring Gear

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

The upper standard size crankshaft bearing shells are supplied as replacement parts with the color codings blue, yellow and red, the bottom standard size crankshaft bearing shells with the color codings blue, yellow, red, white and violet. They should be matched according to the table. It is therefore no longer necessary to gauge the bearing play.

Fig 2: Locating Punch Marks For Matching Crankshaft Bearing Shells

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Special tool 

Fig 3: Identifying Special Tool (363 589 02 21 00)

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When performing repairs, it is not permitted to use HELI-COIL inserts for the self-locking stud bolts of the crankshaft bearing caps.

Fig 4: Locating Self-Locking Stud Bolts

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The 5 crankshaft bearing caps manufactured from malleable cast iron are fitted in at the side of the crankcase (arrows).

The fit (arrows) is off-centered so that the bearing caps can be installed only in one position.

The three middle bearing caps are additionally bolted to the side walls of the housing.

The crankshaft bearing caps are machined together with the crankcase and are not available as a replacement part.

Fig 5: Locating Crankshaft Bearing Caps Side Of Crankcase

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Normal bearing shells and thrust washers  are installed at crankshaft bearing 4 (fit bearing).

The thrust washers absorb the axial forces of the crankshaft.

The thrust washers (9 and 10) inserted in the crankcase and in the bearing cap on both sides are identical.

The thrust washers in the bearing cap each have two catches, the once being positioned off center, as an anti-twist lock and to avoid installation errors. In addition, all the thrust washers are chamfered at one end. The two oil grooves in the thrust washers must face toward the crank webs.

When servicing crankshafts, the fit bearing journals must be re-ground in width to one of the dimension stated in the table (section "Data").

If bearing damage has occurred, the conrods must be removed and any swarf present removed from the conrod bores and the crankshaft oil passages.

Fig 6: Locating Crankshaft And Crankshaft Bearing

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Carefully clean the oil passages in the crankcase, crankshaft, timing case cover, oil filter cover, end cover, oil pump etc.

Examine crankshaft for cracks, dimensional tolerance and hardness.

Matching crankshaft bearings, installing crankshaft 

1. Install crankshaft bearing caps; pay attention to the marking, 1 is at the front.

   The fit is off-centered (arrows); the crankshaft bearing caps can therefore be installed in only one position.

2. Oil contact surface of nut and thread, nuts M8 X 1: tighten to 30 Nm, nuts M10 X 1: tighten to 50 Nm.
3. Oil the thread and the head contact surface of the side bolts (M8 X 60) and tighten to 30 Nm. (Use bolts of quality 10.9 for the side mounting of the bearing caps.)
4. Measure crankshaft bearing bore at two levels in the direction A, B and C (conicity) and note the measurements obtained.

   If a crankshaft bearing bore exceeds the specification or is conical, dress the bearing cap at its contact surface on a dressing plate to not more than 0.02 mm.

   Fig 7: Identifying Crankshaft Bearing Bore Direction A, B And C

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5. Insert bearing shells and install crankshaft bearing caps.

   Tightening torque:

   Nuts M8 X 1: 30 Nm

   M10 X 1: 50 Nm

   Side bolts M8 X 60: 30 Nm

   Fig 8: Identifying Bearing Shells And Crankshaft Bearing Caps

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6. Measure bearing diameter and note.
   Fig 9: Measuring Bearing Diameter

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7. Measure crankshaft bearing journal, determine the radial play of the crankshaft bearing.
   NOTE: The bearing play can be corrected by replacing the bearing shells (see table for matching crankshaft bearing shells to crankcase).
   Fig 10: Measuring Crankshaft Bearing Journal Radial Play Of Crankshaft Bearing

   Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
8. Measure width of fit bearing journal and of fit bearing. Determine axial play of crankshaft bearing (see table in section "Data").

   The fit bearing shells of the repair sizes are supplied over-sized.

9. Treat bearing shells in crankshaft with SAE 30 engine oil and insert crankshaft. Install bearing shells with oil bore into the crankcase.
   Fig 11: Measuring Width Of Fit Bearing Journal And Fit Bearing

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10. Oil thrust washers with engine oil and insert into the grooves at the fit bearing (crankcase).
    Fig 12: Inserting Bearing On Crankcase

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11. Install fit bearing cap.

    

    Hold both thrust washers tight when installing the fit bearing cap.

    Fig 13: Installing Bearing Cap

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    The two oil grooves (arrows) in the thrust washers must face toward the crank webs.

    Fig 14: Locating Thrust Washers Oil Grooves

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12. Install crankshaft bearing caps.
13. Tighten crankshaft bearing caps to the specified torque in the order of the tightening diagram. Oil the thread and the bolt head and contact surface of nut, respectively, for this step.

    Tightening torque:

    Nuts M8 X 1: 30 Nm

    M10 X 1: 50 Nm

    Side bolts M8 X 60: 30 Nm

    NOTE: Use bolts of quality 10.9 for the side mounting of the bearing caps.
    Fig 15: Identifying Crankshaft Bearing Caps Tightening Sequence

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14. Measure axial play of crankshaft bearing.
15. Rotate crankshaft by hand and check whether it runs freely.
    Fig 16: Measuring Axial Play Of Crankshaft Bearing

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    Matching conrod bearings and installing 

16. Install pistons and conrod (03-3160) .
17. Oil bearing shells, crankshafts, pistons and cylinders with SAE 30 engine oil. Install conrod together with pistons (03-3160) .

    

    Pay attention to marking!

    Install the bearing shells with the oil bore in the conrod otherwise the conrod bushes will not be lubricated.

    Fig 17: Locating Marking On Conrod Bearing

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18. Tighten conrod nuts and conrod bolts (03-3100) .
    Fig 18: Tightening Conrod Nuts And Conrod Bolts

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19. Measure axial play of conrod bearings.

    Ensure that the bearings have proper clearance in the piston.

    

    Disassemble oil pump, clean, replace if necessary. Replace oil delivery valve. Clean oil filter. Carefully clean air-to-oil cooler or replace.

    Install initial operation oil filter element. Change engine oil and oil filter element after 1000 - 1500 km.

    Fig 19: Measuring Axial Play Of Conrod Bearings

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