I was wondering if anyone knew what this part is and what its function would be. Its located directly behind the Brake booster on an 1985 300TD Wagon.

Its been disconnected from the electrical connectors for months now. I havent noticed anything in particular since its been disconnected but i would like to reconnect it anyway. The plastic casing for the aluminium female ends is broken and the female ends are themselves broken so Ill have to do either a solder job or rig something up.

Thanks for any knowledge anyone has.

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That is the switchover valve for high/low vacuum for the transmission during warm-up. Below 50 degrees C the transmission gets a higher vacuum to ease shifting, when the engine gets above 50 degrees, the vacuum decreases.

It is nr. 125 in the vacuum scheme below:

Interresting. Thats good to konw. I do have clunky shifting. and I always thought it had to do with the Vacuum system but I wasnt sure where to start.... (and when) I konw now. Ill see if it make a difference and post the results.

Thanks alot.

The 1985 system is rather complicated, but if it works, it produces smooth shifts. You need a vacuum gauge and preferably a combined hand vacuum/pressure pump to test the system. There might be some threads about this system, here or at Benzworld.