Hey, I have a vacuum problem. Well, when I first got the car, the vacuum would run out overnight and the doors would not automatically unlock in the morning. So first I replaced the master vacuum switch in the driver's door. This made it so my locks would work up to after 2-3 nights of the car not being used.

I decided to replace the 3-way vacuum door valve because it's a cheap part and it seems to be a likely culprit for the problem I was having.

I also decided that at the same time I'd clean up the vacuum lines because the previous owner had removed the EGR (I believe using Brian's kit) but had left the vacuum lines to the black box on top the engine. So I removed the two three-way vacuum connectors and replaced them as per Brian's instructions. I also changed out a bunch of the rubber vacuum hose pieces with new hose while I was at it.

Unfortunately, this worsened the vacuum leak. Now it drains out in one night again.

So here are some photos to check out to see if my set up is all correct. Any advice would be greatly appreciated.

Ok, so in image #1, you can see the EGR is no longer there. There is that vacuum line (labeled #1) which has been fed back into itself. Should that even be there anymore?? And also look at the black box (labeled #2) which has no vacuum lines anymore.

In image #2, here is where all the work was done. As you can see, I removed one of the 3-way connectors are added a piece of vacuum hose (labeled C). I left that brown orifice (labeled B) on there as I read another thread saying it should remain there.

Vacuum hose piece (labeled H) used to be a 3-way connector.

G is the 4-way connector that the 3-way door valve connects to.

D and E (new vacuum hose) connect to line F. I noticed that in the schematics I've seen and in other people's photos, that D and E are reversed on mine in regards to where they connect to line F. I tried switching them and that was no good, as my engine didn't want to shut off. So I switched them back to the way they were.

Is there a chance that I messed up something behind the firewall when I was connecting the door valve? I had to pull on the yellow plastic vacuum lines in order to hold them tight. I tried to look in there but I couldn't see where the yellow lines go to. I saw them come out the firewall and I know they eventually make their way to the driver's door, but couldn't follow them from the wall to the door.

Could the problem be the 3-way and 4-way connectors I have left? Since I removed the plastic lines from them, maybe they're too stretched out now??

Ok, any advice would be great. I don't have a MityVac yet. I first wanted to make sure I have all the lines connected properly.

By the way, with the set up as in right now, once the car is on, everything seems fine. Door locks work, transmission seems to shift smooth, brakes work, A/C works.

Thanks,
David

Attached Thumbnails

   

__________________
1985 300D. 179,000 miles.

The black box on top of the oil cover switches the air on when you get out of idle and switches the vacuum for the egr at high revs. Frst is not essential, but makes upshifts softer. The egr I have disconnected (240D) and no problems.

I suggest you search the forum for a vacuum diagram for your car and use that. Also, a mityvac is a must have for these cars - makes testing components sooooo easy. I got mine pretty cheap at Harbor Freight. Use it to test if you have any leaks and where they are.

it is also essential to get the right orifice (you called it a grommet I think) at the vacuum supply, so that the volume of vacuum is correct going to the whole transmission vacuum setup.

This may be off the topic you asked about, but worth getting right.

I looked at a vacuum diagram and it shows that my D and E should be switched.... but when I switched them, the engine took like 10 seconds to turn off.

Also, a vacuum diagram won't reflect the removal of the lines to the EGR. So for anyone who has removed their lines to the EGR, does my setup look correct? Did I do the line removal correctly?

And yeah, orifice, I knew when I wrote grommet it was totally the wrong word. I believe mine is the correct one as it was already there and the lines didn't look like they had been messed with before.

Thanks,
David

__________________
1985 300D. 179,000 miles.

Everything that you did in the photos is correct.

My only comment is a question regarding the vacuum hose. It appears that you've used injector return line for that task, correct? While I cannot swear that it will not work properly, any reason that you have not used standard vacuum hose? Are you confident that the return line hose fits very well and does not leak?

Your leak is not great. Overnight is just a very tiny leak. The wrong hose can cause this.

Brian, thanks for letting me know I did it correctly, that's good to know. Thanks for being such a great help on here.

The hose is the vacuum hose Performance Products sells. They are local here so I went and picked some up there instead of waiting to ship in some genuine Mercedes hose (and it's a rip-off at the dealer here). I believe the hose is actually for Porsche's but they told me it was the same size. I'll probably get some genuine Mercedes hose though and try it out. Although my fingers are going to hate me for doing it again. Which leads me to ask, if there an easier way to get vacuum hose on!?!?!? My fingers are all cut up and sore! Haha, it's in the name of stamping out a vacuum leak so I suppose it's worth it.

I figure I'll switch out to genuine hose, replace the 3-way and 4-way connectors and see what happens. Is there any reason to replace the tiny hard plastic lines? Mine seem fine.

Oh, so could me pulling on the lines through the firewall disconnect anything accidentally? I can't really tell what's going on back there.

Thanks,
David

__________________
1985 300D. 179,000 miles.

OK, I wasn't familiar with them. If they fit well onto the Tecalan lines, I don't see any reason to use the dealer hose. If you really had to work to get them over the plastic line, then they do not leak.

Some of those 3 way and 4 way connectors may leak if they are original.

There is no reason to replace the hard Tecalan lines unless you break one of them (easy to do when they're 20 years old).

I don't believe that pulling a line through the firewall will have caused your issue.

With a leak that small, you're probably not going to find it without the use of a Mityvac.