Mystery of the missing vacuum canister. - PeachParts Mercedes-Benz Forum

TILE GUY · #1 01-03-2008, 11:16 AM

I bought an '84 300TD wagon about two weeks ago. The vehicle was advertised as having vacuum issues, primarily the door locks and a shut off issue. I suspected the door lock master switch and set out to diagnose. Everything has checked out except for a black vacuum line that enters the firewall into the steering column and is left disconnected. I believe it is supposed to be hooked to a canister behind the drivers fender. There is no cannister, but there appears to be a bracket where one would be mounted. The previous owner told me he purchased the vehicle from a body shop that had repaired the front end. I suspect they either forgot to install the canister or it was lost in the accident. I'm unable to find much information about the vacuum system and would appreciate any info on the subject. Thanks, TILE GUY.

JimmyL · #2 01-03-2008, 11:20 AM

There is a smaller diameter black vac line that terminates where you say. It is a vent line of some kind.
I have no idea about the vac cannister you speak of. I've heard of them but never found them on my cars.....

#3 01-03-2008, 11:28 AM

I've also never seen the mystery canister, the black line under the dash is supposed to be an open vent. You most likely just have a vacuum leak someplace.

Jeremy5848 · #4 01-03-2008, 12:49 PM

These cars (123) have a vacuum reservoir for the door locks, for when the engine is not operating. In sedans (and presumably coupes), the reservoir is in the trunk. In the T-sedan (station wagon), it's under the floor at the back of the cargo compartment. You lift up the floor and then remove the trim panel underneath. The T-sedan's reservoir is long and narrow compared to the one in the sedan; both look like an array of black eggs (and so are sometimes known as "egg carton" reservoirs).

Yes, there are black vent lines that terminate under the dash. The idea is that when a vacuum-operated device is released, air has to come from somewhere and clean air is better. So instead of venting from the engine bay, the passenger compartment is used. Unfortunately, Mercedes didn't terminate these lines with anything (a nice little screen with a label "vent" would have been nice). People get confused, think something has come undone.

Jeremy

TILE GUY · #5 01-03-2008, 01:04 PM

Thanks. I'll continue to hunt for the leak. Does anyone have a source for a guide or diagram for these vacuum system?

rrgrassi · #6 01-03-2008, 02:02 PM

There is a sticky titled "vacuum Diagrams for the w123 and w126."

MBeige · #7 01-03-2008, 04:13 PM

The small black vacuum line under the dash is a vent line. The missing canister on the front fender is for the Klima/Kilma relay, if it's missing yes you'll have vacuum problems. It's a blue saucer shaped device that has multiple vacuum lines going to it. Its function is supposedly to amplify the vacuum and make shifting smoother.

The vacuum reservoir is inside the front fender, it's 3 globes stacked on top of each other. Only the yellow-gray vacuum line from the master vacuum switch on the driver door attaches to it as far as I know.

whunter · #8 01-03-2008, 04:45 PM

of egg crate location attached.

Have a great day.

Skid Row Joe · #9 01-03-2008, 11:21 PM

Quote:

Originally Posted by TILE GUY

Thanks. I'll continue to hunt for the leak. Does anyone have a source for a guide or diagram for these vacuum system?

Mercedes-Benz doesn't use "cannisters." That's only found on older American made cars, trucks.
If you have a vacuum problem on a Mercedes-Benz, don't look for a cannister. Vacuum test your lines.

#10 01-03-2008, 11:26 PM

Quote:

Originally Posted by Skid Row Joe

Mercedes-Benz doesn't use "cannisters." That's only found on older American made cars, trucks.
If you have a vacuum problem on a Mercedes-Benz, don't look for a cannister. Vacuum test your lines.

Joe, he's referring to the vacuum tank/canister/whatever shown inside the left front fender here:

http://home.comcast.net/~phantoms/vacuum/interlock_system_layout_1_0203.jpg

JimmyL · #11 01-03-2008, 11:57 PM

Quote:

Originally Posted by Craig

Joe, he's referring to the vacuum tank/canister/whatever shown inside the left front fender here:

http://home.comcast.net/~phantoms/vacuum/interlock_system_layout_1_0203.jpg

I still have never seen one, or seen a vac. line running to it. Do all W123's have this triple decker "cannister".......

#12 01-04-2008, 12:06 AM

Quote:

Originally Posted by JimmyL

I still have never seen one, or seen a vac. line running to it. Do all W123's have this triple decker "cannister".......

I don't know either, and I've never had a reason to go looking for it. Is it possible only the gasser W123s have it? I just posted the link so SRJ would know what "canister" the OP was referring to in his post.

JimmyL · #13 01-04-2008, 12:15 AM

Quote:

Originally Posted by Craig

I don't know either, and I've never had a reason to go looking for it. Is it possible only the gasser W123s have it? I just posted the link so SRJ would know what "canister" the OP was referring to in his post.

Craig, waaay too much effort on Skid Marks behalf. You're a good dude.....

Mismost · #14 01-04-2008, 12:35 AM

Tile Guy...Pop that hood and count up all the little vacuum connectors...buy new ones, and get some extra vac line and just replace all that 24 year crap...then start vacuum testing! Be gentle, those plastic vac lines get brittle. It's amazing how much stuff runs off vacuum in these old cars. Get the vacuum system tightened up and everything works better...even the dang radio sounds better. Besides, do 'em all and still won't cost 10 bucks...cheap fix!