Pistons With Rings And Pins - BMW M57 Service Training

DI Diesel Engines M57/M67 - Common Rail

Pistons with rings and pins

The piston forms the moving bottom wall of the combustion
chamber. Its specially designed shape contributes to ensuring
optimum combustion. The piston rings seal off the gap to the
cylinder wall so as to ensure high compression and as little gas
possible enters the crankcase.
The following features apply both to the M57 and M67:
• Cooling duct piston with rotationally symmetrical piston crown
bowl specific to DI common rail
• The lobe in the piston crown bowl is higher than on the M47
Fig. 23: Sectional view of combustion chamber
M67-specific features
• The pistons of cylinder bank 1 (1 - 4) and cylinder bank 2
(5 - 8) differ as the valve arrangement is not symmetrical
(different valve pockets on piston);
the pistons are identified accordingly
© BMW AG, Service Training
Course contents/Background material
as
KT-3688
Sec. 2 P.17