1984 300D Vacuum change-over valve?

Where is a vacuum change-over valve/solenoid located on said vehicle and what does it do? Also how can the part be tested out?

Forums

Diesel Engine Specific Aid

Chassis Model Number

W123

Location and Function

The changeover valve I think you are referring to should be mounted on the firewall next to the brake booster. Sometimes these are removed by previous owners. It functions to reduce fuel flow from the injection pump in the event of a turbo over-boost condition. A complete description is covered in my manual Diesel Performance Tuning and Repair and testing procedure should be covered in the factory engine service manual.

1984 300D change-over valve

Thanks Kent for getting back. Yes I am aware of the change-over valve you are speaking about as I have your Diesel Performance booklet for some time. But somewhere along the way, in my quest to learn as much as I can about these cars, I came across someone mentioning a "vacuum" change-over valve. This confused me as the change-over valve you mention works off boost pressure not vacuum. Thought there may have been a "vacuum" valve also that I knew nothing about. Thanks for clearing things up.