Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   PeachParts Mercedes-Benz Forum > Mercedes-Benz Tech Information and Support > Diesel Discussion

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 07-25-2021, 01:38 AM
Registered User
 
Join Date: Aug 2019
Location: Ellicott city, MD
Posts: 267
What is Black Vacuum line???

Hi, I have a 1986 190D.

I have a loose black vacuum line at the driver's side firewall that is not connected to anything. It is just laying there.

There is a series of vacuum lines that go through the firewall at that location for door locks that is connected to a yellow circular junction. The black line is just laying there and I think it may be the source of a vacuum leak that is causing my car to not turn off immediately.

The vacuum pump tests good and so does the shut off switch.

Anyone know where that black line should be connected?

Thanks!

Reply With Quote
  #2  
Old 07-25-2021, 03:19 AM
Registered User
 
Join Date: Aug 2010
Location: Sacramento, CA
Posts: 3,147
In my 1985 300D, a black vacuum tube goes from the VCV atop the injection pump thru the firewall where it is open to the cabin air. That is a purposeful leak into the VCV. The flow is restricted by the VCV and a fixed orifice to establish a vacuum pressure signal which indicated accelerator pedal position, and sent to the transmission's "vacuum modulator" (probably via a "blue saucer" in your 1986). That setup is like an electrical "voltage divider" or "potentiometer". I put a small filter in that line since didn't want any debris getting sucked in from the "clean" cabin air.
__________________
1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans
Reply With Quote
  #3  
Old 07-25-2021, 08:21 AM
Registered User
 
Join Date: Sep 2004
Posts: 8,971
Quote:
Originally Posted by dsvw View Post
The black line is just laying there and I think it may be the source of a vacuum leak that is causing my car to not turn off immediately.
Try plugging the line and see if that solves your shut down problem. (I am betting that it won't.)
__________________
When cryptography is outlawed, bayl bhgynjf jvyy unir cevinpl.
Reply With Quote
  #4  
Old 07-25-2021, 08:22 AM
Registered User
 
Join Date: Aug 2019
Location: Ellicott city, MD
Posts: 267
Thanks.
So that black vacuum line does not go to anything? Just the open air in the cabin?

Is the black vacuum line you speak of in your car also found on the driver's side firewall, along with the vacuum lines for the doors?

I do not even see a hole where that vacuum line would go through into the cabin.
Reply With Quote
  #5  
Old 07-25-2021, 08:27 AM
Registered User
 
Join Date: Sep 2004
Posts: 8,971
Quote:
Originally Posted by dsvw View Post
So that black vacuum line does not go to anything? Just the open air in the cabin?
That's the way it is on a W123. It's a vent for the VCV, as described by BillGrissom in post #2. The line enters the cabin through the firewall near the steering column.
__________________
When cryptography is outlawed, bayl bhgynjf jvyy unir cevinpl.
Reply With Quote
  #6  
Old 07-26-2021, 11:43 AM
pawoSD's Avatar
Dieselsüchtiger
 
Join Date: Oct 2004
Location: Grand Rapids, MI
Posts: 15,438
Yup its like that on the W126 also, its just so the bleed air for the VCV is drawn from a reliably clean/dry source of air inside the car rather than out in the engine compartment.

__________________
-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)
Reply With Quote
Reply

Bookmarks


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -4. The time now is 08:22 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2025, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2024 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page