Correct ;

The check valve causes residual vacuum pressure to remain inside the big brake booster can for 'emergency' use .

The .05 nipple should be open but slightly harder to blow / such through ~ for this reason I use it for the V.C.V. on the injection pump as I don't often want much vacuum going to the tranny's modulator .

I am not sure if Mercedes says to use this nipple for the tranny vacuum control valve .

If your nipple has any glue around it's base it has been snapped off and repaired, the glue used plugged the nipple and you can ever so gently drill it open again is you wish .

In any case, if the white plastic part of the check valve looks chalky, cracked or simply isn't shiny anymore it's toast and is just waiting to snap and cause no vacuum at all, I'd buy a new vacuum pipe before you get stranded .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better