Loose black vac line under the dash - PeachParts Mercedes-Benz Forum

hofler · #1 08-16-2007, 12:07 AM

I was snooping around under my dash to see if I had a leaky ignition vac valve and noticed a black vac line that was not plugged into anything. Can anybody give me hint as to where to plug this one in. Also is it a bad sign to have black oil on your ignition cylinder near the vac valve? And while I am on the topic the ignition vac valve leaks down in about 20 seconds. I guesse that is bad, Yes?
Thanks
R

rhodes2010 · #2 08-16-2007, 12:13 AM

Black line under dash is a vent line. It is not connected to anything.
So do not worry about that. The theory is that cabin air is cleaner than
under hood air. Leave it unplugged.

Oil leaking from the shut-off valve can mean that the vacuum pump diaphragm
ruptured. It may have been ruptured before, leaked oil, then repaired.
It is a super easy fix and cost very little.

Cleaning it is not too hard and will let you see if it still leaks.

My new favorite cleaning agent is brake cleaning fluid with the small tube.
I clean vacuum lines and whatever, it dries fast.

On the leak down... not sure. If the engine shuts off that is what matters.
Most people experience the run on engine.
It may not matter that it leaks down.

How well do your door locks work ?
Can you lock and unlock 4 or 5 times ?

JimmyL · #3 08-16-2007, 12:20 AM

Ditto on the vent line under dash.
However, it does sound like you have a bad shutoff valve. It is the diaphram in the shutoff valve, which is attached to the back of the IP. You need to replace it fairly quickly as oil will foul all your vac lines, and cause issues.
Find a thread about replacing the shutoff valve, and read up. It isn't hard, but you have to get it installed correctly in the IP so that it actually shuts off the car.

Here is an old thread about the valve replacement. there are also others.....

IP Injection pump shut off shutoff replacement

hofler · #4 08-16-2007, 05:52 PM

Thanks for the heads up on the vac line. I would have worrined about that for a good while.

I tested my shut off valve with my hand vac pump and it shuts off the engine imediately when I pump up the vac. I don't think my shut off is bad cause of the reaction of the shut off relative to my applying vac manualy. Perhaps in the past like was sugested by rhodes2010 it may have leaked.

In any event I tested the ignition vac valve at the point under the dash where the brown lines are inserted into the largeer rubber vac lines that actually go tot the vac valve on the ignition, thats when I noticed the black oil. It was not dripping but there was some there externaly. I have ordered a replacement valve but will test further this weekend as I will probably be pulling the instrument cluster to take a closer look and install a new window relay. Hopefully that will get the windows working so I can drive again in the New Orleans heat untill I can get the money together to tackle the AC that is not working.

If it aint one thing it is another

R