Hi:

I have a 1984 300 Turbo Diesel and had a vacuum system question . . .

I've been doing some reading and have found that a number of people have removed the 3/2 vacuum switchover valves on top of their valve covers in order to deactivate the EGR valve.

I noticed there wasn't any such hardware on top of my valve cover (see attached photo), so at first I thought the previous owner may have done this.

However, looking at the vacuum routing diagram on the car (see below), I'm not seeing any vacuum-related line or fitting connected to the throttle. What I am seeing are references to an "electric vacuum control valve" (14.20) and/or "Electric switch-over valve-bypass (33.11) connected to the EGR valve.

Were the vacuum switchover valves typically seen on many of these cars online (mounted on the top of the valve cover, with the black plastic cam and white plastic levers actuated by throttle position) replaced with electric switchover units by Mercedes-Benz at some point for the model year of my car? Based on the diagram, it looks this was the case, but thought I'd ask all of you here.

Thanks,
Eric

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