Engine removal and installation, ventilation, cran,  M110

Checking, drilling and honing cylinder bores

 

 
01—110 Checking, drilling and honing cylinder bores

 
Data

 

 

 

 
Group number1)

 
0
1
2
Standard dimension 86.0
piston dia.
cylinder dia.
85.970-85.982
85.998-86.008
85.980-85.992
86.008-86.018
85.990-86.002
86.019-86.028
Repair stage 1 + 0.5
piston dia.
cylinder dia.
86.470-86.482
86.498-86.508
86.480-86.492
86.508-86.518
86.490-86.502
86.519-86.528
Repair stage 2 + 1.0
piston dia.
cylinder dia.
86.970-86.982
86.998-86.008
86.980-86.992
87.008-87.018
86.990-86.002
87.019-87.028

 
Decisive for association is the smallest measured cylinder dia. and the largest measured piston dia.

 
Max. wear limit in driving or transverse direction of cylinder bores at upper reversing point of 1st piston ring
0,10

 
When new
0,025-0,035

 
Piston clearance

 
Wear limit
0,08

 
Machining tolerances

 
Permissible deviation (radial distance) from cylinder shape
When new
0,007

 
Wear limit
0,025

 
Permissible deviation from square with reference to cylinder height

 
0,05
Mean height of roughness

 
0,002-0,004
Permissible height of waviness

 
50 % of roughness
Chamfer of cylinder bores

 
see fig. point 2
Conventional tools

 

 
Inside measuring instrument for 50—150 mm dia., with 0.01 mm readout and measuring point pressure relief
e.g. made by Hommel Sunnen GRM-2125
Handel, 5000 Koln 71

 
Note

 
In particular for a complaint concerning “excessive oil consumption” a measurement of the cylinder bores is essential in addition to a visual inspection.

 
01.2-110/1 F3

 

 

 

 
1 Measure the cleaned cylinder bores with an internal tester at measuring points 1, 2 and 3 in longitudinal direction A (piston pin axis) and in cross direction B.

 
When the pistons are installed measuring point 3 will be just barely above the piston, which must be at BDC.
m110 - 0028-1.jpg
a top reversing point of first piston ring
b BDC of piston
c bottom reversing point of oil scraper ring
The group number punched into crankcase (arrow), matches the group number of the pistons installed as standard equipment.
On used engines, the original cylinder dia. shows up after thorough cleaning of top land zone.
The difference in diameter of dimension shown on top land zone and the dimension at measuring point 1 generally indicates the respective max. wear.

 
In the event of repairs, hone cylinder bores according to dimensions of available pistons plus piston clearance.
The processing machines used for boring (pre-honing), finish-honing and polishing should be set in accordance with respective operating instructions.

 
Upon boring, the cylinder bores should be chamfered at upper cylinder end according to drawing.
The lower cylinder end should remain sharp edged without burr.
m110 - 0028-2.jpg
01.2-110/2 F3

 

 

 

 
01—120 Grinding crankcase mating surface

 
Data

 
Height of new crankcase
213.1-213.2
Min. height after removal of necessary material
212.8
Permissible deviation from parallel of upper parting surface in relation to lower parting surface in longitudinal direction
0,1
Permissible deviation from flatness of upper parting surface
0,03
Mean height of roughness of upper parting surface
0,005-0,020
Leak test with 1.5 bar air gauge pressure under water. Permissible leak rate in cc/min
10
Chamfer of cylinder bores
see note
Piston spacing in relation to parting surface

 
Engines with normal compression
USA version and low compression

 
Distance between piston crown and crankcase mating surface
Standard size piston Below
min. 0.20 max.0.70
above 0.25 below 0.15
Oversizes + 0.5 and 1.0
Below
min. 1.0 max. 1.5
below
min. 0.55 max.0.95

 
Conventional tools

 

 

 

 

 

 
Surface grinding machine

 

 
e.g. made Scledum,
by Ruaro u. type RTY
Fi.,
Schio/ltaly
Knife-edge straightedge approx.
750 mm
long

 

 

 

 

 
Note
m110 - 0029-1.jpg
Chamfer cylinder bores after grinding.
Adjust valve timing (05—215), if crankcase mating surface has been machined.

 
01.2-120/1 F3