Mount crankshaft radially in bearings - AR03.20-P-4355-01AW

CRANKSHAFT BEARING CAP

CONNECTING ROD

Fig 1: Identifying Dial Gage (001 589 32 21 00)

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Mounting main bearing radially 

1. Install crankshaft bearing caps

   The crankshaft bearing caps are installed to fit on the side of the crankcase. The fit is off-centered 0.5 mm with the result that the bearing caps can be installed only in one position. If installed correctly, the lug (arrow) on the crankshaft bearing cap points to the left when viewed in direction of travel (inlet side).

   The crankshaft bearing caps are machined together with the crankcase and must not be interchanged.

   Fig 2: Locating Crankshaft Bearing Cap

   Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
2. Measure crankshaft bearing bore in direction A, B and C at two levels (out-of-roundness).

   If a crankshaft bearing bore exceeds the specified size or is out-of-round, dress bearing cap at its contact surface up to max. 0.02 mm on a dressing plate.

   Fig 3: Identifying Crankshaft Bearing Bore Dimension

   Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
   Fig 4: Measuring Roundness Of Crankshaft Bearing Bore

   Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
3. Measure crankshaft bearing bore in direction A, note measurement obtained, example: 62.51 mm.
4. Take off crankshaft bearing caps.
5. Measure crankshaft bearing journal Ø example: 57.95 mm.
6. Determine bearing shell thickness, example:

   bearing bore-Ø	62.51 mm
   crankshaft bearing journal Ø	-57.95 mm
   	4.55 mm
   Radial bearing clearance	-0.04 mm
   Inspection data → Table of "Crankshaft bearing clearance"

   	4.51 mm : 2
   Bearing shell thickness	2.255 mm

   Fig 5: Measuring Diameter Of Crankshaft Bearing Journal

   Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

   Only one bearing shell thickness is available for repair size crankshaft.

   The crankshaft should be reground to match the stated repair bearing shells + radial play.

7. Assign bearing shells,

   example:

   Bearing shell thickness 2.255 mm → Table "Test values of crankshaft bearing shells"

   Upper bearing shell "blue"

   Lower bearing shell "blue"

   If the thickness of the bearing shell differs, install thicker bearing shell in bearing cap.

   Mounting conrod bearing radially 

8. Insert conrod bearing shells into conrod bearing cap, fit on conrod bearing cap with conrod bearing shells and tighten conrod screws to the tightening torque.
9. Measure conrod bearing in direction of conrod and note the measurement obtained.
   Fig 6: Measuring Conrod Bearing In Direction Of Conrod

   Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
10. Measure connecting rod journal and determine connecting rod bearing radial play.

    Determining conrod bearing radial play 

    Measurement Ø-conrod bearing

    • - Measurement Ø-conrod bearing journal

    = Radial conrod bearing play

    The connecting rod bearing shell are only available in one bearing shell thickness (color yellow).

    For repair size crankshaft, the conrod bearing journals should be re-ground to match existing repair bearing shells + radial play.

    Fig 7: Measuring Connecting Rod Journal And Connecting Rod Bearing Radial Play

    Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
11. Unscrew conrod bearing screws and remove conrod bearing cap.
12. The dimension (B) on turbocharged engines differs from that on naturally aspirated engines in order to ensure the installation position of the connecting rod bearing shells.
    Fig 8: Identifying Connecting Rod Bearing Shells Dimension

    Courtesy of MERCEDES-BENZ OF NORTH AMERICA.