Greetings all. I've been quietly reading all the vacuum related threads and running searches, etc. Replaced the vacuum shut off switch on my '84 300D turbo last night, plugged leads to both yellow lock lines (next project) and ta dah, I've got a brand new car! Incredible. No more sledgehammer to the floorboards every time the trans drops back into first when slowing down. Just a seamless shift.

I know everyone gets tired of the vacuum questions from new to Benz guys like me but your time isn't wasted!

Thanks!

Fred Burgess
84 300D turbo @ 372,000 (do I hear half a million...?)

Hi Fred
Where is that vacuum shut off switch located and what is the part #?

Thanks


David


__________________
1985 300D Turbo

David,

The vac switch is inserted into the back of the injection pump. If you look down between the injection pump and the oil filter housing you'll see a round cylinder sticking out of the pump. It protrudes about 1.5" and is about 2 inches around. Brown with blue stripe vac line from firewall (and start switch in dash) is attached to the top.

You have to move some vacuum hoses - I also removed the white plastic vacuum switch that sits on the injection pump, over the shut off valve. There are (4) 6mm bolts (10mm heads) in a "collar" plate that holds the switch into the back of the injection pump.

It's pretty easy, just have to take your time working the wrench. Trick is getting the "arm" of the shut off valve hooked in place when you insert the new valve. I got it first time, used my hand vac pump to be sure that the shut off was pulling the lever inside the injection pump. Be careful with this as one thread warns that you could jam injection pump to full throttle...that would be exciting!

There are some good threads about how to determine if the shut off valve is shot - before you mess with it!

Part number from FastLane is D2020-11537, ,cost me $38.09 and was worth every cent!

...on to door locks, windshield and rear window seal, and then $ (ie; air conditioning!) Don't care! Love this tank! Fred

Hi Fred
Thanks for the information on vacuum shut off valve location and part #.

I have another question to ask if I may. On the Fastlane on-line
catalog, there is another "vacuum shut off valve" (@ steering for diesel shut off) part. Do you know what is that part for?

Thank you


David


___________________
1985 300D Turbo

Dave,

Oh sure, let me do all the legwork! Ahem, now that I am an expert...the vac switch "steering" is up there on back of the "ignition" switch. When you turn the key off, it opens this "valve" so that vacuum is applied through it, back through the firewall in the brown tube with blue stripe, and into the top of the vac switch on back of injection pump. If everything is in order the diaghram in that vac switch moves towards the firewall and pulls the metal arm attached to it, which in turn pulls a lever inside the pump and shuts off the fuel.

If you search vacuum shut off valve, vacuum switch, that kind of stuff, and spend lots of time reading you can find out how to determine if one or both are goofed up.

You probably already saw it, but if there is lovely black oil inside these brown tubes, or dripping out from under the dash, the vac switch at the injection pump is definitely shot. Mine was full of oil - not air - when I pulled it out.

Are we having fun yet or what!!??

F