My '85 300SD makes a clunk as it downshifts when I approach a stop light. After reading thru posts on similar issues in the forum, I've been going thru my vacuum lines looking for leaks.

I think I've found a leak, but I'm not sure where this vacuum line terminates. It's red/green and is plugged into a 4-way junction near the brake booster. When I unhook this line and plug up the receptacle on the junction, I measure 20 Hg of vacuum at the vacuum supply line to the transmission modulator. When the red/green line is attached, I measure no vacuum at the vacuum supply to the transmission.

Strangely, when I hook up my mighty vac to this mysterious red/green line, it holds vacuum.

I've attached a few images. Please forgive how I've named things in the pictures. I don't know the proper names.

If someone could identify this mysterious red/green line for me, or point me to where it is illustrated on some diagram (I looked and couldn't find it), I would really appreciate it.

Thanks,

Zac

P.S. This post seems similar, but I'm not sure if we're describing exactly the same thing.
http://www.peachparts.com/shopforum/showthread.php?t=237683

Attached Thumbnails

   

There are lots of good threads, pictures and diagrams on this if you do a search. The line with the green dash pot (going to the trans.) should be coming out of the top center of the transducer not the side. I'm walking out the door or I would post some links up for you. I'll do it when I get home if no one has replied.

__________________
AJ

1985 300D (SOLD)

I am not sure if this will help or not, but you are aware that there are two other connections on the bottom of the VCV? There is an control part on the firewall and my recollection is that it recieves vac from the main line.
I had a similar problem and it took forever to figure out. You have found the vac diagram sticky.
Also check out this post. http://www.peachparts.com/shopforum/showthread.php?p=1291383
good luck. Is a pain to get it right, but very nice once you get it working.

__________________
1985 300 TD 448K
1984 300 TD 278K

1983 240D euro 240k
1994 f-250 idi turbo 330K
1986 f-350 IDI
1987 F-350 IDI

1985 JD 1050 4wd
1965 IH 3660

Lets not confuse things by naming things improperly. The VCV is over on top of the injection pump. It only has 2 lines. One is vacuum supply that goes into the top of the VCV and the other is a vent line that runs off the side of the VCV and into the cabin. The other part you may be thinking of (on the firewall) is one of the "switchover valves".

The Vacuum Transducer is located on the Drivers inner fender and is commonly referred to as the "blue flying saucer". The Vacuum Transducer has 4 vacuum lines connected to it. 2 on the top and 2 on the bottom.

In my above post I was incorrect. The line with the dashpot does come off the top side of the Vacuum Transducer at the top.

Here is a link that has a good vacuum diagram and some pics of various items. http://www.peachparts.com/shopforum/showthread.php?t=271702

__________________
AJ

1985 300D (SOLD)

The search function will work wonders, folks:
http://www.peachparts.com/shopforum/showthread.php?t=105297&highlight=vacuum+diagrams

__________________
Think Alternative Energy!
300CD '80 (now gone but not forgotten...)

Yep.... As previously stated.

Funny thing is that there is a vacuum diagram sticky at the top of the "Diesel Discussion" page.

__________________
AJ

1985 300D (SOLD)

There is also http://www.peterschmid.com/

under mercedes click on the vac diagrams.

Charlie

__________________
there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

That is a good one! I have spent a lot of time reading over at that site.

__________________
AJ

1985 300D (SOLD)