Technical information
Pistons n Piston rings n Cylinder liners/finned cylinders
n Gaskets n Assemblies
Types and technical terms
Finned cylinder
Wet liner
Dry liner
Main dimensions
A =Register diameter
B =Maximum permissible finished diameter
for pre-machined liners
C =Collar diameter
F =Fire protection rim height
H =Collar height
L =Total length
MAHLE Original cylinders and liners are perfectly
R =Height of pin bore relief
matched in terms of tribology to the sliding part-
X =Cylinder liner ring
ner components, the pistons and piston rings.
36 | © MAHLE 2012
In accordance with the engine manufacturer’s
If subdivision of defining groups are prescribed by
requirements, MAHLE Original finned cylinders
the engine manufacturer (e.g. colour coding or
and cylinder liners have a finished (honed) or
letters), these have been retained with corre-
semi-finished cylinder bore.
sponding coding for the assemblies.
english
Fitting recommendations for
finned cylinders and cylinder liners
Wet cylinder liner (WN/LW)
The location holes and particularly the seat surfaces on the cylinder block must be cleaned carefully and free of damage. Corroded surfaces must
be reworked (use collar and outer diameter oversize liners). When doing so, ensure that the liners
move easily and that they are correctly positioned
(projecting length of the liner in accordance with
engine manufacturer specification). After the liner
has been fitted with the corresponding sealing
rings (use lubricant), the cylinder diameter must
be checked—particularly in the region of the sealing rings—so as to determine whether any deformation has been caused by pinched sealing
rings. Using incorrect gaskets (diameter and
material) can lead to a narrowing of the cylinder,
which in turn can cause engine damage. The
cooling system should be pressure-tested after
the liners have been installed so as to determine
whether there are any leaks before the engine is
started.
© MAHLE 2012 | 37
Technical information
Pistons n Piston rings n Cylinder liners/finned cylinders
n Gaskets n Assemblies
Dry cylinder liners
Before the cylinder liner is fitted, the location hole
in the cylinder block must be cleaned carefully
and checked to ensure the accuracy of the
dimensions and to determine whether any distortion has occurred.
Out-of-round or damaged location holes can be
reworked for the fitting of oversize liners. It is
important that the location hole is cylindrical, as
this determines the geometrical inner shape of
the press-fit, thin-walled liner.
Semi-finished cylinder liner (WV/LS)
Finished and honed cylinder liner (WT/LD)
The surface, supporting the collar must be verti-
These cylinder liners either fit exactly into the bore
cal to the location hole and sufficiently as well as
of the cylinder block or have a slight overlap. The
evenly bevelled. If the liner collar is unevenly sup-
location hole in the block must be measured
ported, it can break off.
exactly before the liner is fitted.
After fitting the cylinder liner, which is only semi-
As a rule, no oil or grease must be used for press-
finished in its inner diameter, this cylinder bore is
ing in the liners, as it will carbonise and hinder the
finely bored and then finished by honing until it has
heat transfer. Special lubricants such as molyb-
the nominal dimension. For finely bored liners, it is
denum disulphide are better.
only finished by honing (tolerance in accordance
with DIN/ISO H5).
Once the liner has been pressed in, the cylinder
diameter must be measured crosswise at several
The end surface of the liner must be flush to the
sealing surface of the cylinder block; if necessary,
the block surface and cylinder liner must be finished by surface grinding.
38 | © MAHLE 2012
levels (at the top and the bottom as a minimum).
Finned cylinder (WR/LF)
english
In accordance with the engine manufacturer’s
instructions, grey cast iron or light-alloy cylinders
are used.
Light-alloy cylinders (e.g. with running surfaces
made of NIKASIL® or SILUMAL®) are classified
into several groups due to the small installation
clearances in the standard cylinder dimensions.
The following example for three defining groups illustrates the classification for a standard dimension.
Piston
503 81 00
Cylinder
503 WR 27
Defining group identification, diameter
A
94.919 – 94.923
A95.000
AB 94.923 – 94.933
B
94.933 – 94.937
Assembly
503 81 92
Combinations
piston/cylinder
A –A
AB– A and AB – B
B95.013
B –B
© MAHLE 2012 | 39
Technical information
Pistons n Piston rings n Cylinder liners/finned cylinders
n Gaskets n Assemblies
Gaskets for cylinder liners and
finned cylinders
Sealing kits (SK)
These sealing kits correspond to our most common cylinder liners and finned cylinders and can
be ordered using their individual part numbers.
Gasket materials
Material properties of gaskets
Ke
=Keltan/EPDM
In accordance with OE specifications, we offer
Pa
=Paper gasket
gaskets made of peroxide cross-linked material
Pe
=Perbunan/NBR
for engines subjected to heavy loads. These gas-
Si
=Silicone/VMQ/MVQ
kets are set apart in the catalogue by “perox”.
T
=Tombak ring
Vi
=Viton/FKM/FPM
We =Soft iron gasket/shim
40 | © MAHLE 2012
perox =Peroxide cross-linked material
Technical information
Pistons n Piston rings n Cylinder liners/finned cylinders
n Gaskets n Assemblies
english
Fitting recommendations
MAHLE Original assemblies are ready-to-install
and do not require any finish machining. They
comprise pistons with piston rings, piston pins,
circlips, cylinders, and the necessary gaskets.
Please check that the MAHLE Original assemblies
have been correctly assembled prior to fitting:
interchanging cylinders and pistons can cause
engine damage.
© MAHLE 2012 | 41