HERE is a google translated page on the proper tuning of your "klappenstutzen" and pnumatic injection pump for your 200D, 220D, and early 240D's.

On the topic of "klappenstutzen" what does that translate to? As well as "Abregeldrehzahl."

My guess... since I only took Spanish and Latin in high school....
is that it is what would function as an ' air mass sensor' in today's language and design... and it connects to the governor which controls the fuel injection pump

This one is still in use in the OM 616 sold here with all mechanical fuel pumps.

The Steuerpult Abregeldrehzahl is alive, breathing and still works quite well on my W115!

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Never a dull moment at Berry Hill Farm.

From here:

Great translation!

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Never a dull moment at Berry Hill Farm.

I bought a cheap language translation program at Wally World for translating the owners manual on my 240D.

Klappenstutzen comes out as: work out-stops short.

Abregeldrehzahl is not in the dictionary.

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Palangi

2004 C240 Wagon 203.261 Baby Benz
2008 ML320 CDI Highway Cruiser
2006 Toyota Prius, Saving the Planet @ 48 mpg
2000 F-150, Destroying the Planet @ 20 mpg



TRUMP .......... WHITEHOUSE
HILLARY .........JAILHOUSE
BERNIE .......... NUTHOUSE
0BAMA .......... OUTHOUSE

I picked up a nice klappenstutze today at a junkyard, here's some pictures of it for reference.
Pic #1, view from air intake side, at idle
Pic #2, view from air intake side, at half throttle
Pic #3, view from rear, at idle
Pic #4, view from rear, at full throttle

You can see the two flaps in these pictures.
What is not entirely clear to me is what the second flap is supposed to be doing. It is not spring loaded, it opens when the first flap opens but there is no closing mechanism. It just literally flaps around a bit when throttle is released to idle.

Edit: there's also a second thread on this subject, for those interested
615, 616 Pneumatic Governor Adjustment (Translation)

Attached Thumbnails

       

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Tomas, Sweden
1966 Mercedes Benz 230S with OM617.912, automatic. Disk brakes from W108
1983 Mercedes Benz 300TD grey, OM617.912 and 5-speed manual
1983 Mercedes Benz 300TD blue 7-seater, OM617.912 and 5-speed manual

On some occasions the engine would start running backwards,with the exhaust system serving as intake and gasses leaving the cylinders through the air filter...some interesting readings below...
The second flap either kills the engine by holding the exhaust gasses,or gives you the opportunity to do so by the push/pull knob.Earlier 621 series didn`t have the second flap,but the later style intake duct could be installed subsequently.

Attached Thumbnails

     

papillon= butterfly, French. mariposa=butterfly, Spanish