Bought teh car this way. Seems like this isn't just there for looks. Notice the piece with 2 connections and no vac lines connected. I looked up teh diagram and it seems to be somethig with the auto tranny? OM603 engine

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87 300 Touring Diesel - 197K
Bosch Euro Corners

I'm not as up on the 603 as I could be but that looks like your switchover valve to me. It cuts fuel if the turbo overboosts (when it is hooked up anyway).

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1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine

hmm so should one line be running to the ALDA?

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87 300 Touring Diesel - 197K
Bosch Euro Corners

that translates the boost level from your manifold into a pressure signal for your ALDA.

(someone correct me here)

You should trace the clear-ish plastic line on top of your Injection pump to a bolt on the firewall side of your intake manifold to ensure it is routed properly. Then compare it to the vacuum diagrams listed in the 'sticky' at the top of the diesel forum page.

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Actually it just interrupts the boost signal from the intake manifold to the ALDA if it exceeds a set pressure. The line from the intake manifold should run through it before the ALDA

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1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine

It should run through it.. I was hoping the line was still there, but bypassed the valve (someone's fix??)

What does the electrical signal do?

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http://i323.photobucket.com/albums/nn447/Jeremy5848/1987%20Mercedes%20300D/Vacuum603.jpg


top center of the picture - cuts off fuel as bgkast described.

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thanks for the diagram.

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87 300 Touring Diesel - 197K
Bosch Euro Corners

you can actually see the tubes joined together in the second pic. (buzzer sound here)

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yeah looks like they joined the lines - maybe a bad valve they didn't want to pay to replace?

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87 300 Touring Diesel - 197K
Bosch Euro Corners

ditto. Try cleaning it out first.

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This looks just like the new one that I put in my '81 300SD. Notice that the top outlet is clamped off. Then there is a single tube on the top and a single tube on the bottom. I forget exactly where they went but can look and take a picture if you need it. See picture below. By the way these things really work; I had the vac hoses mixed up at first and had zero power. Changed the hoses and have great power.

The clamping of the top outlet is in error. This is the vent to atmosphere. When the solenoid is energized, the horizontal port to the ALDA is connected to the top vent. The hose should be removed and tossed.

Brian - I do not think that is correct. When I took off my original, the top was capped off from the factory; cap was plastic. At least it did not look like it was vented as far as I could see. Are you sure? Do you think the top cap on the original only looked like a cap and was vented? The car has been running great with lots of power with it installed as shown in the picture.

PS - the top hose is only 2 inches long. It has a stopper inside with the clamp over it and the hose stub. I am interested to know if I should for sure take it off and just leave it open to the atmosphere. If so why did the original have a cap?

Yes, the cap was (is) vented.