vacuum hose question - 1978 300D - PeachParts Mercedes-Benz Forum

rgnprof · #1 05-09-2006, 02:39 PM

OK, as I have previously posted, I am close to completing work on the central lock system - couple of questions: The attached picture shows my vacuum hose set-up, but I'm a little confused. What I know is this - the black hose furthest to the right, coming off the check valve, goes to the cruise control, the hose immediately to the left of it (black connector, but the plastic is yellow w/gray stripe), I'm not sure where it goes. I thought that it went to the door lock system and so I have had it disconnected and the check valve capped for the past several months. The next hose to the left (brown) goes through the firewall and I'm thinking it goes to the vacuum box in the trunk. The next hose to the left (red) goes right by the fuse box through the fender wall and I don't know what it does. The next hose is green w/ yellow stripe and I think it goes to the ACC. The next hose to the left (yellow) goes to the master vacuum switch in the driver's door (central connection and it is the suction line). It has been disconnected since I have had the car. Trouble is, I don't even see where it connects?? I'm out of connections under the hood, unless I'm supposed to have some sort of 4 way tee/valve somewhere.

The brown hose furthest to the left conncets to the back of the altitude adjustment box (ADA, or ALDA) and I'm thinking it is the shut-off vacuum.

Can anyone verify, confirm, and/or correct?

In summary, I do not know where the yellow w/gray stripe goes, although it has been capped off for months and I haven't noticed any problems, and I don't know where the yellow hose connects under the hood?

Sorry this is long.

ryan

Rick Miley · #2 05-09-2006, 03:44 PM

The current setup is not anywhere close to correct. Most of the lines are covered in this post: regarding vacuum locks on 240d

But I have no idea what the red one is for.

rgnprof · #3 05-09-2006, 04:52 PM

So how should they be connected? It seems like I have one too many hoses for the connectors??

ryan

rgnprof · #4 05-09-2006, 07:48 PM

Thanks to Rick's post I have figured out all but the red hose (the yellow w/gray strip goes to the vacuum tank in the trunk and the brown hoses are for the ignition and shut-off. I have attached 2 pictures that show the hose (red) from the check valve over to the driver's side fender wall. I can not find it from there - anyone have any idea where this hose goes? Is there another vacuum tank in the fender somewhere?

ryan

I have studied the online manuals, but does anyone have a complete vacuum schematic for this car (1978 300D)

97E300D · #5 05-09-2006, 09:00 PM

I think that the Red hose was used in a different location. As far as I can tell the red line was used under the Climate control servo as a cold engine heat shut off swiich. Other then then that I have never seen the red hose used.

Rick Miley · #6 05-10-2006, 10:00 AM

Since you have made the changes, what works and what doesn't work now?

rgnprof · #7 05-10-2006, 11:37 AM

I haven't had a chance to complete the work on the locks - waiting on a part. But, I have studied the vacuum diagrams from the online manuals for the ACC and door locks and I think the red hose goes to a vacuum supply tank for the AC. I have everything hooked up now pretty much as described in the manual and I will let you know what works as soon as I can get things all back together.

thanks, ryan