I just noticed that there is an electric/pneumatic valve in the engine compartment of my car. Neither of the small pneumatic fittings have hose connected to them. The electrical connectors are intact. The valve is located on the sheet metal in front of the brake master (on the engine side of the sheet metal) near the oil filter. Look above the bellows on the line coming out by the brake master in the attached photo (if this works).

What is it? The car runs like a top so I guess I don't need it.

Thanks
Dave

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1986 300SDL

try this photo again.

Attached Thumbnails

 

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1986 300SDL

The valve you show is PROBABLY the switchover valve that opens (when triggered by the overboost protection switch on the intake manifold) to prevent an overboost condition from destroying the engine. There are several similar valves in the engine compartment but I belive that the one you circuled is the overboost control.

It is NORMALLY open (with NO power to it) and closes off the pressure source (the intake manifold) from pressurizing the ALDA (that supplies fuel enrichment in proportion to boost) and vents the ALDA so that NO fuel enrichment occurs. This prevents the excess air pressure from the turbo from producing excess power but leaves sufficient power (~109 vs 148 hp) to allow it to be driven almost normally.

In the picture you posted, there is a pressure line appearing to go directly from the side of the intake manifold to the ALDA (atop the rear of the injection pump. This is the line that should be interrupted by the switchover valve (which should be open unless powered by the overboost sensor on the intake manifold.

Marshall

Thanks for the help. Looks like somebody just unplugged the lines from the valve and stuck them together. I'll check the valve and see if it's open or closed.
Dave

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1986 300SDL