Shut off valve change on the launch pad-wish me luck

[showme]

I'm getting ready to change my shut off valve in the 81 300d shortly. I've been having to manually kill it under the hood for a while, and I've got the part. Tried to find vacuum leaks last weekend, but I'm apparently doing something wrong in that dept. I have a mityvac, and I get the fundamentals, but I'm losing patience, so I'm just going to replace the valve with a new one, weather it needs it or not. I've got a sunny, decent day here in Missouri and the DIY from dieselgiant, so it's "curb service" time again. Unless every thing goes along without a hitch, I'll probably be back with questions (as usual), so "Stay Tuned!" out there all you smart fellers.

[4thesporty]

Just make sure to have something in place to cut off air in case of a runaway engine at startup.

[toomany MBZ]

The attachment is from the Factory Service Manual.

Pay attention to it's orientation as it comes out, you need to line up the new one just right.

[showme]

Ok, I'm done putting it in. Surprised me by only taking an hour start to finish. I followed dieselgiant's pictorial instructions, which really helped. I checked the old valve, and it wasn't holding vacuum. It was leaking off pretty quickly, at that. That made me feel better, since the car lately (I guess after changing some dry rotted connectors) would act like it was going to die, then "come out of it" and return to regular idle speed. I checked the new valve, and it held the vacuum indefinitely, so I put it in, being careful to put it back the way the old one came out. That's where dieselgiant's instruction really helped, because I loosened up the ALDA cover and made sure it was in the right spot, and checked the arm movement with my mityvac before replacing the cover. Here's the bad news. The shut off valve took 9-10 in\hg to pull the lever over far enough to engage far enough for shut off. My vacuum pump seems to be getting 7.5 tops. Is that right?? What's a vac pump's standard in\hg's? Anyway, the parts in, but it's still not shutting the engine off, and I even tried revving it while trying to shut if down to see if I could get more vacuum so it would pull 9-10 like I saw when I had the ALDA opened. I even went directly to the pump after disconnecting the main hose off of it, and still got about 7-7.5 hg. I figure rebuilding the vac pump is the next step if it's not putting out enough. If it is, is there a possibility that I did something wrong when I put the ALDA cap back in place? And, yes, I did put the metal gasket between two new paper gaskets, and all was hooked back up properly. What the heck am I missing here?

[bobodaclown]

Your lacking vac. Should be at least 15.

http://www.dieselgiant.com/mercedesvacuumtroubleshooting.htm

http://boostnbenz.1baddsm.com/DIY/easley/Rebuild_vac_pump.htm