I bought the car about a month ago,its an 84 190d with the 2.2 4 cylinder .I located a junk yard pump and began its replacement.When inspecting the old unit it had shrapneled inside the area it was mounted.The pump is basically a piston and spring thats attached to a roller that rides on a roller coaster type piece of metal,as the crank of the motor turns the roller rides up and down .I cant find the roller bearing from the piece and also an arm on the assembly is gone.Somewere in the pan Im sure.This had no effect on the motor running but I would suggest as soon as you notice a problem with your vacuum pump to not drive it til you can safely know of why its not working properly.Ill be pulling the pan and run a magnet thru it to see if the motors been on a metal diet.