PRE-RELEASE
Pistons
| Pistons |
| General data |
|
Engine
|
B204i/B204E/B205R/L
|
B235R
|
|
|
Mean piston velocity at 5000 rpm (m/s)
|
13
|
15
|
|
| Important | ||
|
Pistons of different manufacture must not be used in the same engine. The name of the piston manufacturer is cast inside the piston. |
||
| Piston types |
|
Engine
|
|
R
|
Ø
|
A
|
H
|
|
|
B204i
|
mm
|
55
|
42.3
|
4.4
|
68.3
|
|
|
B204E
|
mm
|
150
|
70
|
4.4
|
68.3
|
|
|
B205L/R
|
mm
|
74
|
28.65
|
1.4
|
56.2
|
|
|
B235R
|
mm
|
50
|
70
|
3.8
|
56.9
|
|
Pistons B205L/R, B235R
| Classification of pistons and cylinder bores |
The piston classification is stamped on the piston crown roof. Piston classifications for service are:
AB
B
C
The cylinder classification is stamped on the cylinder face and is specified for each cylinder. The cylinder classifications are:
A
B
B+
They can all occur in the same cylinder block.
| Piston classification |
|
B204
|
B235R, B205L/R
|
||
|
Standard A
|
mm
|
89.971 - 89.980
|
|
|
Standard AB
|
mm
|
89.980 - 89.989
|
89.9664 - 89.975
|
|
Standard B
|
mm
|
89.989 - 90.000
|
89.975 - 89.982
|
|
Standard C
|
mm
|
90.000 - 90.013
|
|
|
1st oversize (0.5)
|
mm
|
90.472 - 90.488
|
90.457 - 90.475
|
|
2nd oversize (1.0)
|
mm
|
90.957 - 90.975
|
|
|
Piston clearance, nominal
|
mm
|
0.011 - 0.040
|
0.025 - 0.056
|
|
Classification, piston/cylinder
|
|
Clearance
|
|
|
|
|
|
|
|
A/A
|
mm
|
0.020-0.041
|
|
|
AB/A
|
mm
|
0.011 - 0.032
|
0.026-0.056
|
|
AB/B
|
mm
|
0.014 - 0.040
|
0.055-0.032
|
|
B/B
|
mm
|
0.006 - 0.031
|
0.025-0.055
|
|
B/B+
|
mm
|
0.011 - 0.041
|
| Piston diameter |
The piston diameter is measured at right angles to the gudgeon pin hole 11 mm from the bottom of the piston skirt.
| Piston rings |
|
Upper compression ring
|
Lower compression ring
|
Oil scraper ring
|
||
|
Thickness B204
|
mm
|
1.728 - 1.740
|
1.475 - 1.490
|
- 2.500
|
|
Thickness B235
|
mm
|
1.475 - 1.490
|
1.978 - 1.990
|
2.976 - 3.052
|
|
Side clearance in groove B204
|
mm
|
0.050 - 0.082
|
0.040 - 0.072
|
|
|
Side clearance in groove B235R, B205L/R
|
mm
|
0.035 - 0.080
|
0.040 - 0.075
|
|
|
Working gap in cylinder B204
|
mm
|
0.30 - 0.50
|
0.15 - 0.65
|
0.38 - 1.40
|
|
Working gap in cylinder B235
|
mm
|
0.300 - 0.500
|
0.300 - 0.500
|
0.260 - 1.020
|
| Gudgeon pins |
|
B204
|
B235R, B205L/R
|
||
|
Diameter
|
mm
|
23.996 - 24.000
|
23.996 - 24.000
|
|
Clearance, gudgeon pin/connecting rod bush
|
mm
|
0.005 - 0.014
|
0.012 - 0.021
|
|
Length
|
mm
|
68
|
63
|
