1. Recognizing MAHLE Pistons Finding Information
Today’s Example- Dodge Sprinter
This piston is an excellent example of both the features and quality on MAHLE made pistons.

2. Ideal Conditions: Brand New Piston!
We are going to examine the replacement piston for the Dodge Sprinter van. It has many features to illustrate the technical merits of MAHLE pistons. Let’s start with the phosphate coating that gives the piston its dull black color as seen here.It protects the piston pin bore from scuffing upon start-up as well as against oxidation while sitting on the shelf plus lubricity to ring grooves. Also of interest is, even though you cannot see it, the piston pin bore is profiled in this application. What that means is the pin bore has a slight ovality machined into it. This allows the pin bore to operate in a round condition as the engine fires and can double the life of the piston compared to one with a round pin bore that becomes out of round during operation.

3. GRAFAL® Skirt Coating GRAFAL® Coating Reduces Scuffing
Reduces Friction
GRAFAL, a registered trademark of MAHLE GMB, is applied by MAHLE to reduce friction, reduce scuffing and allow tighter skirt to wall clearances. You might note that skirt to wall clearances are so critical today that measuring the piston, especially those with GRAFAL, is not an accepted way to calculate the bore size. MAHLE pistons are so exact that the clearance is correct if the overbore size is held to spec!

4. Ni-Resist / Armored Top Ring Groove
Ni-Resist Top Ring Groove
Armored
Gallery Cooled Design
Ni-Resist or armored top groves are quite common on diesel engines. MAHLE went a step farther and developed a gallery cooled piston. A cavity behind the groove is created by using a salt ring in the casting process. After the casting is done, the salt washes out with hot water leaving both the gallery and inlet and outlet. This provides for engine oil sprayed by a piston cooling nozzle in the engine, to cool the top ring and the crown of piston. FYI: Every piston is X-ray inspected to insure the gallery is correctly formed!

5. Identifying A MAHLE Ring Cooled Design
Gallery Cooling Inlet
You can identify a MAHLE piston with cooled top ring by looking on the inside of the piston. You’ll see a round and an oblong hole on opposite sides that allow the oil to circulate in and out., carrying the heat along and away from the top ring and crown of the piston.

6. Understanding MAHLE Markings
Metric Diameter
Minimum Skirt Clearance
MAHLE Production Number
is the metric diameter of this piston
Sp0.07 is the skirt clearance in mm ( adding both these two numbers gives you finished bore of the piston mm)- remember on all GRAFAL coated pistons, you finish to the bore size of, in this case, mm. Do not try and measure the piston and add the clearance, it will result in error!
is the MAHLE part number, not the MAHLE Clevite part number
02 is the oversize, referred to, in this case, as the second oversize which is .50mm ( approximately.020” -actually ”)
S indicates a variation, in this case a “straight rod” vs. an “tapered rod”, you’ll sometimes see a “HA” suffix standing for Hard Anodized, but most of the time will see no suffix

7. Manufacturing Codes Front Of Engine Indicator
MAHLE Production Markings
The arrow, of course, indicates the front of the engine and the piston needs to face that direction when installed.
The block M stands for MAHLE and means the piston is made by MAHLE
1239 is a plant identifier, in this case, a MAHLE plant in Brazil
07 06, indicates the piston was manufactured in July of 2006

8. Casting Number Piston Number Inside Of Piston Bore Size Range
Piston Type
Mold Number
Mold Modifications
Many times customers will only have this casting number from the old piston. Pistons that have seen long service often have the shallow top markings obliterated. In this case we know that this casting was:
Used in a 88mm bore range
L is the piston type, could be several other letters here depending on the design, material, mfg. method, etc.
65 is the mold used
A6 is the change level, indicating the mold or the design has been altered 6 times in the life of the part
Now, you can, if ever the need arises, take this casting number and go to: Once you enter the base # , in this case 88L65, it’ll tell you what the piston fits. This is very useful if a customer has a piston and no application- PS: thanks to Ray Falkenrath for the tip!

9. Are Aftermarket Pistons Different than OE?
Sometimes!
Gasoline replacement pistons are usually reduced compression ht.
Diesel are more and more same as OE
Oil cooled
Profiled pin bores
Special coatings
Profiled shapes

10. Thermal Expansion: Piston w/o Profile
Room Temperature
Operating Temperature 19
MAHLE Industries, Incorporated, RDN, Wolfgang Rein, Feb-2008
© MAHLE

11. Temperature+Inertia+Pressure+Sideforcemax
Piston Deformation
Temperature
Temperature+Inertia+Pressure+Sideforcemax
[mm]
[mm]
Exhaust Valve
Larger Deformation
ATS TS
ATS TS 23
MAHLE Industries, Incorporated, RDN, Wolfgang Rein, Feb-2008
© MAHLE

12. Improving Pin Bore Strength by Adjustments of the Pin Bore Geometry28
MAHLE Industries, Incorporated, RDN, Wolfgang Rein, Feb-2008
© MAHLE

13. Due to Single Ovality in the Pin Bore
Increase of lifetime
Due to Single Ovality in the Pin Bore 29
MAHLE Industries, Incorporated, RDN, Wolfgang Rein, Feb-2008
© MAHLE

14. Using the Web

15. Pistons/Cylinders/Kit sets
Piston and pin dimensions in mm
KH-comp height
UH-dome height
VT-valve recess
MO-comb chamber diameter
GL-total length
AA-distance between pin bosses

16. Piston/Cylinders/Kit sets
Piston ring mounting-shown in listing
ring width in mm
Cylinderbore in mm
Piston with rings,pin and clips-part number

17. Piston/Cylinders/Kit sets
Liner part number
Assembly part number
Piston head configuration

18. Piston/Cylinders/Kit sets
Liner dimensions in mm

19. Practice

20. Dodge Sprinter / Mercedes Benz
Summary
MAHLE
Dodge Sprinter / Mercedes Benz
Phosphate Coating
Oval Profiled Piston Pin Bore
GRAPHAL® Coated Skirt
Ni-Resist / Armored Top Ring Grove
Cooled Top Ring Design
Comes With Rings Installed
In summary, you notice this piston has the combustion chamber located in the crown, obviously a diesel. You, also notice the 4 valve reliefs and the face it comes W/R, with rings already installed.

21. Contact Information
aftermarket.com/C12570B3006C0D49/CurrentBaseLink/W26MNK9W508S TULEN

22. Questions??