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  #1  
Old 09-19-2009, 05:18 PM
azitizz's Avatar
MB 1985 300TD Wagon
 
Join Date: Apr 2009
Location: Winnipeg, Canada
Posts: 422
Where does this Vacuum line lead to?

Im just trying to figure out problems with the vacuum system on my 85 300TD wagon and when testing this particular vacuum line (one pictured) it reads practically zero for vacuum.

Will this be affecting either the transmission or the shutoff? (which are both having problems)
In my vehicle however the line isnt tee'd off like the one pictured it only has one (black one) going straight through the firewall.
Thanks.
Pics courtesy of Dieselgiants website

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Where does this Vacuum line lead to?-shutoffvalve04.jpg   Where does this Vacuum line lead to?-shutoffvalve10.jpg  
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  #2  
Old 09-19-2009, 05:32 PM
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The shutoff line is brown. Although I don't think the transmission vacuum lines go through the firewall, I thought all the transmission vacuum parts were in the engine bay.

If it is the shutoff line, it would only have vacuum when you shut off the car. With the car running, connect the mityvac to that line and draw a vacuum to see if it shuts off the car....if the shutoff actuator is bad, that won't work though.
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Last edited by pizzachef; 09-19-2009 at 05:37 PM.
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  #3  
Old 09-19-2009, 05:40 PM
azitizz's Avatar
MB 1985 300TD Wagon
 
Join Date: Apr 2009
Location: Winnipeg, Canada
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Quote:
Originally Posted by pizzachef View Post
What color is the line that you're asking about?
The shutoff line is brown.

Does the line branch off the main vacuum line (between pump and brake booster) and go right into the firewall or does it come from somewhere else?

Under the dash there is a black vent line that is open to the atmosphere, but I think that's just for the climate control actuators.
The line is Black and no it doesnt branch off the main vacuum line. Simply goes straight from the beige pictured part to the firewall.

on dieselgiants website where I got this pic it was referring on how to remove the shutoff valve and this is one of the lines to disconnect in the process. He also said, if your car has a manual transmisson, it wont have this valve so I assumed it may be related to the transmission?
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  #4  
Old 09-19-2009, 05:44 PM
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smoke gets in your eyes
 
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Black is usually a vent line. It leads through the firewall to the driver footwell and just ends. The function is to provide cleaner cabin air to the vacuum pump. See the horizontal splitter off the VCV (device 65) -



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87 300D
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  #5  
Old 09-19-2009, 05:47 PM
azitizz's Avatar
MB 1985 300TD Wagon
 
Join Date: Apr 2009
Location: Winnipeg, Canada
Posts: 422
Quote:
Originally Posted by sixto View Post
Black is usually a vent line. It leads through the firewall to the driver footwell and just ends. The function is to provide cleaner cabin air to the vacuum pump.
So no need for it to hold a vacuum? what about the valve? should this hold a vacuum? cause neither do when I test them.
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  #6  
Old 09-19-2009, 06:05 PM
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Quote:
Originally Posted by azitizz View Post
So no need for it to hold a vacuum? what about the valve? should this hold a vacuum? cause neither do when I test them.
The vacuum control valve leaks by design. The black line is the vent for the vacuum control valve and the EGR valve. The portion of the black line attached to the 3/2 valves should hold vacuum except at full throttle.
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  #7  
Old 09-19-2009, 06:14 PM
azitizz's Avatar
MB 1985 300TD Wagon
 
Join Date: Apr 2009
Location: Winnipeg, Canada
Posts: 422
Quote:
Originally Posted by tangofox007 View Post
The vacuum control valve leaks by design. The black line is the vent for the vacuum control valve and the EGR valve. The portion of the black line attached to the 3/2 valves should hold vacuum except at full throttle.
Great, thank you very much. thats good to know that no vacuum is natural. what are the 3/2 valves? is this the other 2 valves on the same part? and would vacuum or no vacuum on these valves rule out engine stopping problems coming from this area?
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  #8  
Old 09-19-2009, 06:53 PM
toomany MBZ's Avatar
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Location: central Va
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The 3/2 valve is the component on item #68. That is part of the egr system, many have bypassed it. From your description, yours has been too. The second pic shows a three way connector (distributor in MB speak), coming from the bottom of the VCV, those that have bypassed the system have replaced that with a rubber line that plugs into a black line that goes into the cabin and is a vent, nothing is hooked to it.

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