Crankshaft and flywheel — design description (BMW X5 E53)

The engine crankshaft is a seven-bearing one (Fig. 3.10).



The bearings are made in the body of the cylinder block crankcase in the form of plain bearings. Lubricating grooves are made in the upper liners of the main bearings. Counterweights are made on the shaft cheeks. cast together with the shafts. The crankshafts are divided into three dimensional groups, marked with colored paint marks (yellow, green and white) on the cheeks in the area of the counterweights.

The diameter of the main journals of the crankshaft of the engine "M54":

• yellow mark
• nominal size: 59.984 - 59.990 mm
• size 1st class: 59.734 - 59.740 mm (Reduction by 0.25 mm)
• size 2nd class: 59.484 - 59.490 mm (decrease by 0.50 mm)
• green mark
• nominal size: 59.977 - 59.983 mm
• size 1st class: 59.727 - 59.733 mm (reduction by 0.25 mm)
• size 2nd class: 59.477 - 59.483 mm (decrease by 0.50 mm)
• white mark
• nominal size: 59.971 - 59.976 mm
• size 1st class: 59.721 - 59.726 mm (reduction by 025 mm)
• size 2nd class: 59.471 - 59.476 mm (decrease by 0.50 mm)

Crankshaft axial clearance:

• nominal 0.080 mm;
• maximum 0.163 mm.

Radial clearance of crankshaft main bearings:

• nominal 0.020 mm;
• maximum 0.058 mm.

Diameter of connecting rod journals of crankshaft of engine "M54":

• nominal size: 44.975-44.991 mm;
• 1st repair size: 44.725-44.741 mm;
• 2nd repair size: 44.475-44.491 mm;

Radial clearance of crankshaft connecting rod bearings:

• nominal 0.020 mm;
• maximum 0.055 mm.

The maximum permissible ovality of the surfaces of the main and connecting rod journals is no more than 0.003 mm.