Vacuum Tube Identifiaction - PeachParts Mercedes-Benz Forum

wangchung69 · #1 12-27-2004, 08:00 PM

Please help a newbie in distress. This morning, I could not shut off my car and the door locks was not working. I did some research on this site. I found out that one of my tubes may be loose or may be a leak somewhere in the vacuum tube connections. I found there is a black tube that run from the vacuum control valve into the car compartment not connecting to anything. Is this normal? Is this possibly a Vent line to the compartment? If not where is this tube connect to?

Please help...

dmorrison · #2 12-27-2004, 08:07 PM

OK welcome to the forum But, rule #1 for newbes. What car?????? and a picture is really helpful.

If you cannot provide a picture then at least we need the type of car.

A disconnected vacuum line will produce the symptoms you have. Lets see which one is disconnected.
If it is disconnected, where is the female end, do you see one? What size vacuum line? The size of your pinky 1/2 inch or so, or the size of a straw? Color? Etc.

Give more of a description and we will certainly help.

Dave

JamesStein · #3 12-27-2004, 08:35 PM

That black vacuum line is typically a vent tube and shouldn't go anywhere. I suppose its in the cabin since they figure the air in there will be cleaner than in the engine compartment.

wangchung69 · #4 12-27-2004, 09:05 PM

Thanks for a fast reply. I've got a 1984 300TDT. Please see the attachment for the picture. This Tube run into the compartment under the steering wheel and it is black. thanks

dmorrison · #5 12-27-2004, 09:24 PM

That is your vent line which does go into the passenger compartment so it has "clean air"

http://www.ultrahot.com/vacuum/egr_82_300d.jpg

look at the injection pump and then for the black/white line that goes to "a".

So we need to look other places for your problem.
Start by buying a Mityvac unit. Then lets figure out if you have good vacuum or just a leak. With the Mity vac you can start the process of eliminating components on your system that could be causing the leak.
Quickly you can diconnect and BLOCK ( a golf "T" works well) the door lock and AC system vacuum lines.
The door locks are the Yellow/red yellow/green lines. The Ac system are the Greeen lines. The brown lines are the shut off lines that go to the Injector Pump. Try the door and Ac lines first. Isolate them and see if the car shuts off. If it does NOT then we need the Mityvac to start at the vacuum pump and work our way thru the system.

If the car is old and the 2/3/4 way rubber connectors have not been replaced they do get old and cause leaks.

Dave

wangchung69 · #6 12-27-2004, 10:03 PM

thanks again for your help. I will get the MityVac tomorrow and try figure out where the problem is. I still have one more question. My brake and my AC/heat work fine. Can I eliminate the Vacuum Pump as the culprit?

sam

dmorrison · #7 12-27-2004, 10:34 PM

Chances are yes, but my daughters car had fine brakes and the vacuum pump output was 5 inches.

Check the vacuum pump to know that the main component is OK. It should pull about 22-25 inches.

Its sort of a check list. Start with the primary component and work your way down the system. Its a bear testing all the system components just to find out that the pump is bad or a fuse has blown.

Dave