Dont know what part is missing under frequency valve.
 

Have a 1981, 380 sl,, change the engine mechanic and the 4 cilynders of the driver side, stop working, so I change the frequency valve, same problem, but find out that there is a hole without any part, valve , hose, cover or plug, that I cover it ,and then the 4 cylinders began to work, seems to be a vaccum hole? Can someone help what part does cover that hole or I have just to put a plug.


photo attached

Thanks

Thanks for the information, as one member told me, I put a cap in that hole and now the engine runs perfectly, thanks.