W115 240D Butterfly valve
 

Does the Butterfly valve just flop around are is it supposed to have some type of spring tension?

It's meant to be connected to the accelerator and have at least one spring somewhere as well (couldn't tell you where however)

The outer one is connected via levers to the gas pedal.
The inner one is not supposed to be attached to anything.Its function(the inner ,free one) :
http://www.peachparts.com/shopforum/450221-post10.html

More here (post 38 and 39)
http://www.peachparts.com/shopforum/diesel-discussion/371685-new-project-1976-hanomag-mercedes-206d-van-who-knows-about-3.html

Mine is not connected to anything.

What's your accelerator pedal connected to? Someone swapped in a flyweight governor IP in maybe?

This is the inner butterfly valve the is in front of the orifice that the pneumatic governor hose attaches to.

Subscribed in hope there will be pictures or images......

http://www.peachparts.com/shopforum/...nturi-tube.jpg

http://www.peachparts.com/shopforum/diesel-discussion/110577-200d-220d-early-240d-tuning-guide-2.html

Photos of the intake duct in tompaah's attachments. The outer flap with the cut-out for the pneumatic governor tube (#1 in the scheme above) is connected to the gas pedal. The inner flap is free.
Raison d'être for the inner flap - in the attachments in post #21.

Thank you ~

This appears to be an anti - runaway device, clever .