There are 5 vac lines that go though the firewall on a 84 300SD. Red & Green strip, Brown,Brown & blue strip & 2 soild Black

What do the black lines do?

What are they connected to?

I cant find them once the go through the firewall. I have the under dash cover off & A/C ducts removed.

Both Black lines are leaking and want fix the problem.

Im not talking about the Black line that go's to the trans.

I cant find the black lines in the diagrams posted on the sticky.

Thanks for your help!

__________________
Matt (SD,CA)

1984 300SD.. White/Chrome Bunts..Green

1997 2500 Dodge Ram 5.9 Cummins 12 Valve 36 PSI of Boost = 400+hp & 800+tQ .. ..Greenspeed

2004 Dodge Ram 2500 4x4 Quad Cab Cummins 5.9 H.O "596hp/1225tq" 6 spd. Man. Leather Heated seats/Loaded..Flame Red....GREENSPEED

Global warming...Doing my part, Smokin da hippies..

Fight the good fight!......

Matt,
I know one of the black lines is a vent line, and it is supposed to just terminate under dash. won't hold vacuum. I'm not sure what the other one is. Where does it come from in the engine compartment?

__________________
Jimmy L.
'05 Acura TL 6MT
2001 ML430 My Spare

Gone:
'95 E300 188K "Batmobile" Texas Unfriendly Black
'85 300TD 235K "The Wagon" Texas Friendly White
'80 240D 154K "China" Scar engine installed
'81 300TD 240K "Smash"
'80 240D 230K "The Squash"
'81 240D 293K"Scar" Rear ended harder than Elton John

Standard MB practice is that a black plastic vacuum line is a vent line. They commonly vent the vacuum system from the cabin, in order to keep the system clean, and not suck up a bunch of junk they just lay behind the dash. Unless your car is unusual, black lines are supposed to leak, they're vents/bleeds. I've been looking for some good diagrams for you, but haven't been able to find anything clear. You should eventually find them just dead-ending somewhere back there.

I'm pretty sure red with green stripe is the vacuum source for the ACC. Brown is the vacuum source for the shut-off valve and brown with blue stripe is the line to the shut-off valve. One of the black lines is a vent from the transmission vacuum controller on the IP to the cabin. If there's another black line it's probably the vent from the EGR valve and ARV if it's an 84 CA car. AFAIK the black lines go 6-8" into the cabin and end.

Sixto
95 S420
87 300SDL

yep. i was pondering the same question myself recently. brown and brown/blue lines go through firewall and terminate at the vacuum kill switch at the ignition lock housing. you can see them if you take off the driver kick panel, and look up at the steering wheel from the driver leg area. the red/green line will terminate at the ACC vacuum distribution panel on the right side of the central console, can't see it well without removing the central console. One of the black lines is a vent for sure. Don't know about a vent for an EGR valve on CA cars, mine (federal) doesn't have any such thing.