Crank Drive
Cylinder Grinding and Piston Dimensions - C 26 NE
| Piston diameter must be measured at "D". | |||||
|---|---|---|---|---|---|
| .P. B8729.tif | 6 | 6 | tiff;; | ||
| Cylinders | |||||
| Pistons available | |||||
| Size | Cylinder bore | Coefficient for | Pertinent piston | Coefficient on | |
| Æ in mm | Cylinder bore | Æ in mm | piston head | ||
| on crankcase | |||||
| Production | 1 | 88.745 - 88.755 | 5 | 88.715 - 88.725 | 5 |
| 88.755 - 88.765 | 6 | 88.725 - 88.735 | 6 | ||
| 88.765 - 88.775 | 7 | 88.735 - 88.745 | 7 | ||
| 2 | 88.775 - 88.785 | 8 | 88.745 - 88.755 | 04 | |
| 88.785 - 77.795 | 99 | 88.755 - 88.765 | 05 | ||
| 88.795 - 88.805 | 00 | 88.765 - 88.775 | 06 | ||
| 88.805 - 88.815 | 01 | 88.775 - 88.785 | 07 | ||
| 88.815 - 88.825 | 02 | 88.785 - 88.795 | 08 | ||
| 88.825 - 88.835 | 03 | 88.795 - 88.805 | 09 | ||
| 3 | 88.835 - 88.845 | 04 | 88.805 - 88.815 | 8 | |
| 88.845 - 88.855 | 05 | 88.815 - 88.825 | 99 | ||
| 88.855 - 88.865 | 06 | 88.825 - 88.835 | 00 | ||
| 88.865 - 88.875 | 07 | 88.835 - 88.845 | 01 | ||
| 88.875 - 88.885 | 08 | 88.845 - 88.855 | 02 | ||
| 88.885 - 88.895 | 09 | 88.855 - 88.865 | 03 | ||
| Service | Over - | 89.265 - 89.275 | 89.235 - 89.245 | 7 + 0.5 | |
| size | 89.275 - 89.285 | 89.245 - 89.255 | 8 + 0.5 | ||
| 0.5 mm | 89.285 - 89.295 | 89.255 - 89.265 | 9 + 0.5 | ||
| 89.295 - 89.305 | 89.265 - 89.275 | 0 + 0.5 |
Crank Drive
Cylinder bore C 26 NE
Reboring cylinder Permissible oversize to 0.5 mm
(see Parts microfiche)
After reboring cylinders make original coefficient
on crankcase invalid and stamp in new oversize
coefficient.
Bore
Permissible out - of - round in mm 0.005 *
Permissible taper in mm 0.005
* Measure out - of - round at 4 different bore levels
Pistons C 26 NE
Version Operating piston
Clearance For short block engines and cylinder
blocks with complete pistons, piston
clearance is 0.025 to 0.035 mm.
With repairs (oversize), piston clearance of
0.035 to 0.045 mm is permissible, depending
on pistons supplied.
Piston over upper edge of cylinder block 0.2 mm
Piston rings C 26 NE
1st compression ring
Plain compression ring (molybdenum-coated)
Thickness in mm 1.5
Piston ring gap in mm 0.40 to 0.65
2nd compression ring
Scraper ring
Thickness in mm 1.5
Piston ring gap in mm 0.30 to 0.5
Oil scraper ring
Chamfered expanding spring, 1 -piece
Thickness in mm 3
Piston ring gap in mm 0.30 to 0.60
Ring gap offset 180°
Piston pins C 26 NE
Length in mm 65
Æ in mm 22
Type Floating bearing in con-rod
Clearance
In piston in mm 22.004 to 22.010
In con -rod in mm 22.005 to 22.010
Installation Slide seat
Con - rod C 26 NE
Permissible weight variation of con -rod (without pistons and bearing shells) within an engine is 8 g.
As the con - rods have no balancing studs, reworking is not possible.
Replace con -rods in pairs only.
Note:
For each engine, only con -rods belonging to a single group no. may be installed.
The group nos. are located on the bearing cover.
| Crankshaft Grinding Dimensions C 26 NE | .P. D3139.tif | 6 | 5 | tiff;; | ||
|---|---|---|---|---|---|---|
| Crankshaft journals | Con - rod bearing journals all | Con - rod | ||||
| width all | ||||||
| No. | ||||||
| I to VI | No. VII | |||||
| Guide bearing | ||||||
| Æ mm | width mm | Æ mm | width mm | Æ mm | mm |
Standard size
| N= Normal dimension for crankshaft and con -rod bearing | 58,003 | ||
|---|---|---|---|
| 57,987 | 27,512 | ||
| 27,450 | 58,003 | ||
| 57,987 | 25,080 | ||
| 25,000 | 51,990 | ||
| 51,971 | 24,890 | ||
| 24,838 | |||
| shells | N | N | N |
0.25 mm undersize for Production and Service
| A = Crankshaft bearing shells diameter 0.25 mm undersize | 57,753 |
|---|---|
| 57,737 | 27,712 |
| 27,650 | 57,753 |
| 57,737 | 25,280 |
| 25,200 | 51,740 |
| 51,721 | 25,090 |
| 25,038 |
* = Bearing shell width for bearing VII, 0.2 mm oversize
A = Diameter of con - rod bearing shells 0.25 mm undersize
| 0 = Width of con -rods and con - rod beating journals 0.2 mm oversize |
apply
| A |
|---|
| * |
apply
| A |
|---|
| O |
apply
| A |
|---|
| O |
Crank Drive (Continued)
| Crankshaft Grinding Dimensions C 26 NE | .P. D3139.tif | 6 | 5 | tiff;; | ||
|---|---|---|---|---|---|---|
| Crankshaft journals | Con - rod bearing | Con - rod | ||||
| No. | ||||||
| I to VI | No. VII | |||||
| Guide bearings | journals all | |||||
| width all | ||||||
| Æ mm | width mm | Æ mm | width mm | Æ mm | mm |
0.5 mm undersize for Service
B = Crankshaft bearing shells diameter 0.5 mm undersize
* = Bearing shell width for bearing VII, 0.4 mm oversize
| B= Con -rod bearing shells diameter 0.5 mm undersize | 57,503 |
57,487
apply
| B | 27,912 |
27,850
| * | 57,503 |
57,487
apply
| B | _ |
|---|---|
| 51,490 |
51,471
apply
| B | _ |
Crank Drive (Continued)
Crankshaft C 26 NE
Crankshaft and con - rod bearing journals
Permissible out - of - round in mm 0.004
Permissible taper in mm 0.012
Radial runout Permissible radial runout of centre
crankshaft bearing journal when installing
shaft in cylinder block:
0.03 mm
Permissible end play in mm 0.04 to 0.16
Permissible main bearing play in mm 0.02 to 0.06
Permissible con -rod bearing play in mm 0.01 to 0.06
Permissible con- rod end play in mm 0.11 to 0.24