PeachParts Mercedes-Benz Forum - View Single Post

LUVMBDiesels · #12 05-09-2008, 08:49 AM

If you are talking about a brass colored round thing that sits next to the square thing on top of the injection pump, then you are talking about the shut of valve. the shut down system has four pieces, a vacuum line going to the dashboard and connected to the shut off switch attached to the key switch, a vacuum line going from this switch to the shut off valve on the IP.

If you do not have a line on the shut off valve, look for one that is brown in color that runs from the firewall to near the IP. That is the line you need to connect. If it is connected and the car does not shut off when you turn the key, disconnect it and put a vacuum gauge on the line. When you turn the key to off (engine running) you should get abpporx 22 PSI of vacuum at the end of the line. If you do not get that, check the vacuum lines and the switch in the dash (PITA to get to)

If you get the vacuum at the end of the line, try this. Take a clean piece of hose and attach it to the shut off valve. With the engine running, suck on the other end of the hose and watch the stop lever. It should move towards the off position. If you can suck really hard and get the car to shut off, it is probably a leaky valve. If you have a Miti-Vac, you can use it to create vacuum on the end of the hose. The MV will not generate the same amount of vacuum as your lungs so if you are pumping the MV and the stop lever kind of wobbles the valve is bad.

I just replaced the SOV in the 300SDL and it was a pain getting it out without taking the intake manifold off. I did it though by taking the Xover pipe off and yanking the ALDA (square thing near the SOV)

Good Luck!