I need help working on my 83 240d. Im trying to fix my vacuum leak problem and am having trouble. I've read thru countless DIY's and the more i read the more i get confused. If some one has a few hours and can help me id appreciate it. I can drive it too you. I have a little bit of money but not a lot left, thought I replaced the right parts but i was wrong..

message me if willing
Thanks,
Derrick

I can't help but have you posted what you have already done in another Thread?

I have a leak somewhere and the only issue I really had to be careful of was that the Trunk did not get permanently Locked. That is because I do not have a Trunk Key that works.
The Locks can be worked manually. You just need to remember to lock them; the same with the Trunk if you have the Key.
The Climate control seems to default to the Defroster and you need that for safety reasons.
So for the above stuff you take picture or make a drawing of where the Tubings go where the connect to the Rubber connector. Disconect them and Plug of the side of the Rubber Connector that the Vacuum is coming from.


So that only leaves 2 areas the Vacuum Shutoff and the Power Brakes.

It is inconvenient but the Engine can be shutoff by opening the Hood and using the Manual Shutoff lever or you can run a Vacuum Hose from the Shutoff inside of the Car and use a hand held Mighty Vac or simply suck on the Hose to get the Engine to shutoff.

If the Power Brakes are having issues you first need to see if the Vacuum Pump is putting out enough Vacuum.

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84 300D, 82 Volvo 244Gl Diesel

what is the vacuum leak manifesting as? is it something that's making the car hard to drive (bad shifting, no shut off with the key/ignition) or is it something like no central locks?

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1981 NA 300D 310k miles

I assume from your handle you have a 240D 1983 just like me.

The 240D's vacuum system is real simple and color coded.

The big black line starts at the vacuum pump and goes directly into the brake booster.

Off the main vacuum pipe there are 2 taps. Be careful, if you bust the tap nipples off you have to replace the whole pipe, it is $$$.

First tap goes to the engine bay EGR/transmission control stuff. This is the tap closest to the front of the car. See http://www.dieselbenz.info/images/vacuum_engine_pp.jpg for the details.

Second tap goes to the cabin. This is the line that heads rearward over the oil filter, and has a 3-way splitter and a white check valve in the line. On the 240 there are only 3 systems in the cabin that use vacuum:

- Engine shutdown valve on the IP - brown hose that goes inside, to the vacuum switch behind the key, and back out to the IP shut down actuator.

- Climate control - green hose, ends up on the passenger side on a vacuum solenoid beside the glove box, then on to the recirculation actuator in the center of the dash. This is what gets activated when you roll the AC temperature wheel to MAX. The AC wheel applies electricity to the solenoid beside the glove box to apply or remove vacuum from the actuator.

- Locks - 2 yellow hoses beyond the check valve, one goes to the vacuum tank in the trunk under the back window, and the other to the master vacuum switch inside the drivers door. From the vacuum switch there are yellow/red (lock) and yellow/green (unlock) hoses to the various lock actuators. There are taps under the carpet under the driver's and passengers feet. The driver's door only gets locked mechanically. When you move the lock mechanism in the drivers door (either by the key or the plunger) it also moves the master vacuum switch to supply vacuum to the other doors/fuel tank door/trunk. This is probably the source of your problem, the plastic lines flex every time you open/close the doors and this causes the lines to crack and fail after 30 years.

Note that there are two black vent hoses that penetrate the firewall and dead end behind the dashboard. You can see these in the link referenced above. These are used by the transmission control circuits (driver side) and EGR circuit (passenger side) to release the vacuum when appropriate to the actuators. The vent lines pull the cleaner air behind the dashboard (as opposed to the wet and dirty air in the engine bay) to restore the system to atmosphere when needed. These hoses are supposed to just be hanging there behind the dash.

With a MityVac you should be able to trace out the various circuits and see which one(s) cannot hold vacuum.

If you do not have access to a MityVac then use golf tees to plug the rubber connectors to attempt to isolate the problem. For example, to rule out the climate controls, unplug the green hose from the connector in the engine bay, and stick a golf tee in the rubber connector where the green hose came from, to seal it off. Then see if your vacuum issue goes away. If it did then you know the problem is in the climate controls.

Be careful, if you drive in this condition for too long. Your vacuum pump is not meant to operate continuously (i.e. if the system is leaking) and this will trash the bearings in the vacuum pump. If the bearings fail, the parts get ingested into the engine timing chain and cause catastrophic engine failure. Not trying to scare you but just wanted you to know that it is important to resolve this urgently.

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The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

I think its my master switch in my driver door. All my hoses seem good when i put pressure in them, rubber conection seem good (holds pressure as well),trunk holds pressure, ill check th black climate lines,

but the master switch in driver door leaks air when i tryn pump it up.. that would mean my master switch is done right?. when i remove the switch and hook up my mityvac to the red/yellow or the green/yellow the locks work great, hook back up the master and they fail

Yes that part often fails. Not terribly difficult to replace and not too expensive. I believe there are 2 different kinds. When you check with Phil to order your new one, be sure to give him your vin# so he can get you the right one.

Worst part is getting the door apart without breaking things.

Until you get it fixed be sure to pull the yellow line at the 3-way under the hood and plug the connector with a golf tee to save your vacuum pump. You will have to lock and unlock all the doors manually but it beats frying the engine.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

i blocked off that yellow check valve and unpluged the solid yellow line from the master switch. i have a new one coming tomorrow so hopefully that do the trick.
thanks everyone for the help

Likely the vacuum pods in the dash are broken. I could get to them without pulling the dash on my 84SD. Not sure about the 240. Find someone with the FSM. It will make many things easier.

Since cash is tight, replace the diaphragms instead of buying all of the pods. Pods are ~ $70 eash, diaphragms are ~ 8. search. I think the details are here.

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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.