I have a vacuum leak in my 85 300D. I have done a fair amount of "mitivac research" and determined that the green hose with a yellow stripe that comes through the firewall to the engine compartment will not hold a vacuum. Can someone tell me where it attaches inside the cab? From reviewing posts, I think it links into the HVAC system, but not sure.

If so, I have a couple of questions:

1. How difficult is it to trace the line into the cab? Will it require removing the dash? Will it require multiple test through a number of pods to find the leak (like is required for door lock related leaks)

2. If I just plug the line in the engine compartment with a golf tee, will the buttons that control my AC and Heater still function?

I really appreciate everyone that posts to this forum. If you were not here giving me repair tips, I'm sure I would not have continued to buy more and more Mercedes over the years. I believe I (my family) now owns 7 cars (two are parts cars).

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02 E320 Black (198K)
85 300D Blue (147K)
83 300D Blue (299K)
Plus 2 300D Parts Cars
05 ML350 Silver (165K)
02 ML320 White (207K)

The green is the climate control (HVAC). No need to remove the dash. I believe all connections can be accessed with the knee panels removed. Worst case, the CCU needs to be removed for access to the vacuum valves. With no vac to the valves, everything should work except the vac pods that control air flow. The blower will just distribute the air through the channels/vents that are open.

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All Diesel Fleet
1985 R107 300SLD TURBODIESEL
2005 E320 CDI (daily)

LOTS of parts for sale!


EGR block kit
http://www.peachparts.com/shopforum/diesel-discussion/355250-sale-egr-delete-block-off-plate-kit.html

1985 CA emissions 617 owners- You Need This!
Sanden style A/C Compressor Mounting Kit for your 616/ 617 For Sale + Install Inst.

Sanden Instalation Guide (post 11):
http://www.peachparts.com/shopforum/diesel-discussion/367883-sanden-retrofit-installation-guide.html

They're only for the central locking so cap them off under the hood and drive happy until you decide to diagnose and fix the leaks .

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-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

A. Hard plastic green vacuum line with yellow stripe: climate control system.
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B. One end attaches to the 3-way plastic yellow check valve near the oil filter canister. The other end attaches to a (I think) 5(?)-port rubber distributor just left of the climate control unit. This end can be accessed after (carefully) removing the panel fitted above the driver's feet. So what one has is an approximately 3' length of hard plastic green vacuum line with yellow stripe, one end on the engine side of the firewall, one end on the driver's side of the firewall.
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C. If you desire to be successful with a M-B vacuum system, NEVER plug a vacuum line with a golf tee! Why? Because they often do not fully seal...you think they are doing so but the joke is on you. Instead, utilize a smooth metal slug available at a hardware store.
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D. If you plug the end of the hard plastic green vacuum line with yellow stripe at the engine compartment side of the firewall, you are eliminating vacuum for everything downstream. This means that the switchover valves behind the climate control unit will switch when buttons are depressed but without vaccuum to be controlled, the vacuum elements that the valves control will remain stationary. All else will remain operable, so far as I know (my brain is not a perfect operation).

DUH ! .

Thank you for the correction ~ I was thinking yellow pipes with stripe....

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

Thanks everyone for your replies.

At present, I have plugged the green line in the engine compartment. This has temporarily resolved my vacuum issues (slow door locks, delayed/coughing engine shut off). Since I am not sure which CC pod may be leaking, I just plugged the line in the engine compartment. Since I am not presently ready to invest the time to locate which of the 5 pods may be leaking, this seemed like the best temporary solution.

I realize it has crippled the effectiveness of the "buttons" but not sure how to address the issue if I don't research each pod. And that will take a time commitment I can't make right now.

Thanks again.

__________________
02 E320 Black (198K)
85 300D Blue (147K)
83 300D Blue (299K)
Plus 2 300D Parts Cars
05 ML350 Silver (165K)
02 ML320 White (207K)

Here's a simple and stress-free way to look at the situation:
Each vacuum element---receiving vacuum, not receiving vacuum, leaking vacuum---has a diaphragm and control rod that is in a position of one sort or another at any given point in time. The attached flap is thus in a position of one sort or another at any given point in time. Added together, this means that so long as there is air flowing through the system, the air will exit at a variety of locations. The air flow exit locations may not be what you desire, but the air will exit nonetheless. To my way of thinking, not a particularly onerous issue.