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  #1  
Old 07-01-2019, 09:46 PM
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Question Requesting Primary Vacuum Systems audit

1983 300D Turbo - Automatic

Would like someone with a good eye to see if this vacuum setup works or suggestions how to clean it up.
https://i.imgur.com/qPRLPP9.jpg
https://i.imgur.com/bdqAMlj.jpg
https://i.imgur.com/JbNXfdm.jpg
https://i.imgur.com/c6SrciW.jpg

Notes:
-EGR, Vacuum temp sensor are plugged with vacuum caps. 5way on top off valve cover is bypassed.

-Central locks disabled, HVAC disabled.

-Overboost valve: Top port goes to ALDA, bottom port connects to rear of manifold banjo.

-VCV: Top port goes to transmission, bottom port connected with black hose goes to cabin, as a vent.

Iím mainly concerned with the mess above the VCV. There are many 3 way connectors that lead to know where.

Iím getting proper vacuum tho, I believe (I donít remember the vacuum acronym) 24 vacuum and 16 from transmission.
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  #2  
Old 07-01-2019, 09:55 PM
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Vacuum is measured in inches of vacuum.
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  #3  
Old 07-02-2019, 02:02 AM
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Quote:
Originally Posted by BWhitmore View Post
Vacuum is measured in inches of vacuum.
And how much vacuum is an inch of vacuum?


Inches of mercury, or sometimes water.
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1978 300D, 373,000km 617.912, 711.113 5 speed, 7.5mm superpump, HX30W turbo...not yet legal
1984 240TD>300TD 121,000 miles, *sold*
1977 250 parts car
1977 280> 300D - 500,000km+
1999 Hyundai Lantra 1.6

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  #4  
Old 07-02-2019, 02:09 AM
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Quote:
Originally Posted by Wusha View Post

-Overboost valve: Top port goes to ALDA, bottom port connects to rear of manifold banjo.
None of which has any connection to the vacuum system.
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  #5  
Old 07-02-2019, 02:27 AM
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If you’re concerned with the mess on the VC, have a look at a vac diagram. IIRC, what’s up there is one vac line straight from the manifold, one line from the connections on the IP, and one going to the EGR. Those could all be removed.

The rest of your system should follow the diagrams available here and elsewhere. Body consumers include the two yellow lines for locks, green for hvac, brown for shutoff and one more. Engine and trans consumers go to one of two spots on the IP, and a black tube that goes to the AT.

Start getting rid of golf tees and move to basic splitters/junctions...
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Current Diesels:
1981 240D (73K)
1982 300CD (162k)
1991 350SD (113k)

Past Diesels:
1983 300D (228K)
1985 300D (233K)
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  #6  
Old 07-02-2019, 02:30 AM
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Quote:
Originally Posted by NZScott View Post
And how much vacuum is an inch of vacuum?

It depends on the size of the container. It's really confusing, because a small container can hold more inches of vacuum than a larger container. And the more vacuum you squeeze into a container, the less it weighs. But it's hard to find vacuum that's much over two feet long. (That's why you seldom hear about a yard of vacuum.)
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Old 07-02-2019, 03:20 AM
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Quote:
Originally Posted by tangofox007 View Post
None of which has any connection to the vacuum system.
Are you saying it’s connected wrong or that it has nothing to do with vacuum lines?

I’m just trying to get my car ready for a 4 hour road trip. Not concerned with locks/AC.

My brown connectors are fine. Car shuts off 1 second after removing key from ignition.

Quote:
Originally Posted by JHZR2 View Post
If you’re concerned with the mess on the VC, have a look at a vac diagram. IIRC, what’s up there is one vac line straight from the manifold, one line from the connections on the IP, and one going to the EGR. Those could all be removed.

The rest of your system should follow the diagrams available here and elsewhere. Body consumers include the two yellow lines for locks, green for hvac, brown for shutoff and one more. Engine and trans consumers go to one of two spots on the IP, and a black tube that goes to the AT.

Start getting rid of golf tees and move to basic splitters/junctions...
The diagrams I find are just diagrams with labeled components but lack a Legend explaining those labels. I’ve found plenty on google but they are routed to the 5way connector on top of the valve cover, which makes it confusing.

Thanks for the replies. I’ll get to work cleaning it up. Just wanted to make sure my vacuum to the transmission and IP was okay.

I’m still new to navigating this site. I might not be looking correctly.

Last edited by Wusha; 07-02-2019 at 03:32 AM.
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Old 07-02-2019, 08:07 AM
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Quote:
Originally Posted by Wusha View Post
Are you saying it’s connected wrong or that it has nothing to do with vacuum lines?
It has nothing to do with vacuum system; it transmits manifold pressure to the ALDA.
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Old 07-02-2019, 08:33 AM
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Quote:
Originally Posted by Wusha View Post
Are you saying itís connected wrong or that it has nothing to do with vacuum lines?

Iím just trying to get my car ready for a 4 hour road trip. Not concerned with locks/AC.

My brown connectors are fine. Car shuts off 1 second after removing key from ignition.



The diagrams I find are just diagrams with labeled components but lack a Legend explaining those labels. Iíve found plenty on google but they are routed to the 5way connector on top of the valve cover, which makes it confusing.

Thanks for the replies. Iíll get to work cleaning it up. Just wanted to make sure my vacuum to the transmission and IP was okay.

Iím still new to navigating this site. I might not be looking correctly.
Over boost relay has everything to do with prot citing against too much boost, overfueling/temp, and engine damage. Boost and vac are two different systems used for two different purposes.

It sure what kind of legend youíre looking for. There are reasonable-quality vac diagrams available here and elsewhere on the web. Startek is free for FSMs as well. There is a ton of info and some folks have tried to organize it a bit into threads, you just need to beware that there are lots of different vacuum routing schemes, and some have transmission related vacuum router through the valves on the top of the valve cover (4-5 hoses on those iirc), while others have just three.
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Current Diesels:
1981 240D (73K)
1982 300CD (162k)
1991 350SD (113k)

Past Diesels:
1983 300D (228K)
1985 300D (233K)
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  #10  
Old 07-02-2019, 09:36 AM
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Quote:
Originally Posted by tangofox007 View Post
It has nothing to do with vacuum system; it transmits manifold pressure to the ALDA.
Ok, I should have renamed my title better. I included it because my previous N/A
cars manifold would generate vacuum and had “vacuum leaks”. But I’ve never had a turbo.
Thanks for clearing that up.

Quote:
Originally Posted by JHZR2 View Post
Over boost relay has everything to do with prot citing against too much boost, overfueling/temp, and engine damage. Boost and vac are two different systems used for two different purposes.

It sure what kind of legend you’re looking for. There are reasonable-quality vac diagrams available here and elsewhere on the web. Startek is free for FSMs as well. There is a ton of info and some folks have tried to organize it a bit into threads, you just need to beware that there are lots of different vacuum routing schemes, and some have transmission related vacuum router through the valves on the top of the valve cover (4-5 hoses on those iirc), while others have just three.
Looking into startek, thanks for the info.

And yes, boost is different than vacuum and something I need to understand better.
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  #11  
Old 07-07-2019, 12:31 AM
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Some German translations for items are a bit confusing. What most in the U.S. would term a "vacuum switch", M-B terms "switch-over valve". Their word "druck" for "pressure" slips into terms. The "hot-water solenoid valve" for the cabin heater is termed "mono-valve" (perhaps there was a duo-function valve once?). If remove the emission controls part of the vacuum system, that eliminates ~50% of the components, at least in my 1984 & 85. There is a diagram posted many times here. Be careful not to lose the positions of the several small plastic bleeds (orifices) which are stuffed in the vacuum tees. Those are needed to control transmission shifting correctly and such.

Your emissions controls probably don't work anymore, so removing them may make the engine run better and pollute less. They were to reduce NOx emissions, which are a minor concern today (smog). The current concern is CO2 emissions (global climate change), so maximizing mpg reduces that. If you fill w/ bio-diesel, you emit no "net CO2" so optimal. It is widely available now in CA (Propel & Union 76 stations).
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