Since I do not have one nearby, what are the pistons in a 617 turbodiesel made of? Cast/forged iron/aluminum/boogers?

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Your TACH may have a loose connection...I was wondering why your mechanic would be dead one minute then flopping around the next... PanzerSD

i am inspired. i will replace my windsheild... with an intercooler. swedishK

alloy and covered with graphite

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1986 300SDL, 211K,Dealership serviced its whole life
1991 190E 2.6(120k)
1983 300D(300k)
1977 300D(211k)

The pistons are an alloy of aluminum.

Moly coated alloy, the bottom rings are special material with expansion wire.

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99 Gurkha with OM616 IDI turbo

2015 Gurkha with OM616 DI turbo

2014 Rexton W with OM612 VGT

the moly coating is only on the turbo, correct?

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Usually yes but I have seen Mahle pistons for N/A OM616 with moly coating available for extra premium. They were non squirter type of course.

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99 Gurkha with OM616 IDI turbo

2015 Gurkha with OM616 DI turbo

2014 Rexton W with OM612 VGT

Ok, I think my original question was too vague. A few days ago, I got an old-style (thought it is never used) Mahle turbodiesel piston. I can post a few pictures later if anybody wants. It feels like Al but it seems not to be, say, the same alloy used in VW diesel pistons. It also seems to be cast, not forged. That makes me feel the crystals should have a consistent size across the entire piece.

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Your TACH may have a loose connection...I was wondering why your mechanic would be dead one minute then flopping around the next... PanzerSD

i am inspired. i will replace my windsheild... with an intercooler. swedishK

Casting and forging alloys are different.

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Gone to the dark side

- Jeff

Thank you for enlightening me on that. Now, would you please share with me the alloy composition and grain size of these pistons? I am one of those idiots who really do not know it; there are a few of us out there.

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Your TACH may have a loose connection...I was wondering why your mechanic would be dead one minute then flopping around the next... PanzerSD

i am inspired. i will replace my windsheild... with an intercooler. swedishK

The alloy and grain size will not be apparent to the eye. An experienced eye can descern between cast and forged due to-mostly- the configuration of the inner part of the piston.

I've been in the AL/ZN/MG forging and casting business, there are many alloys for each process depending on what the requirements are of the end product. The US also uses different alloys than DE, etc. We had to source special non-US-standard alloys for Mercedes parts that we produced.

Often the alloy is identified in the casting/forging (for recycling purposes), although I wasn't around back when the 617 was produced and don't know if it was common then.

I don't know much about 617s, but perhaps if I knew what you want to accomplish I can find the information that will help you.

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Gone to the dark side

- Jeff