'82 240D vacuum leak/break - PeachParts Mercedes-Benz Forum

1goos4u · #1 10-21-2006, 11:20 AM

Ok I finally decided to register on the forums here after reading quite a lot of troubleshooting techniques. I have a question about my vacuum system in my '82 240D. The car doesn't shut off when you turn the key off, which I've heard is a somewhat common problem. I had the vacuum pump checked as well as the fuel shutoff solenoid (I think that's what it's called) and they are in working order. I started following the vacuum lines checking for breaks, and found a vacuum line break just behind the battery. The other end is on the other side of the firewall. I am assuming this is what I need to mend. Is this most likely my problem (assuming no other vacuum line breaks), and how do I locate the other end of the vacuum line? Do I need to take out the entire dashboard area? Thanks for any suggestions/help in advance.

MattBelliveau · #2 10-21-2006, 11:40 AM

What color is the line going into the firewall? If it's black, it's a vent and doesn't hook to anything. It's supposed to be open. Is the battery on the 240 on the driver's side? It's on the passenger side on mine. The only vac line that would be on the passenger side would be ALDA related, and shouldn't affect shut-down. Keep posting, I have pretty much rebuilt my whole vac system on mine, and I can help you. Many members will also be able to help.

Stevo · #3 10-21-2006, 11:54 AM

Your on the right track. What you need is a "mity vac" and a hand full of golf tees so you can find the problem by a process of elimination.

1goos4u · #4 10-21-2006, 12:22 PM

Quote:

Originally Posted by MattBelliveau

What color is the line going into the firewall? If it's black, it's a vent and doesn't hook to anything. It's supposed to be open. Is the battery on the 240 on the driver's side? It's on the passenger side on mine. The only vac line that would be on the passenger side would be ALDA related, and shouldn't affect shut-down. Keep posting, I have pretty much rebuilt my whole vac system on mine, and I can help you. Many members will also be able to help.

Yes, it is black. I just got the car in August and haven't done much work on it, and I'll freely admit I don't know what all the lines are yet. The line I was speaking of is black and is running along the edge of the engine compartment along the top of the fender. And yes, the battery is on the passenger side.

Mustang_man298 · #5 10-21-2006, 11:47 PM

Quote:

Originally Posted by MattBelliveau

What color is the line going into the firewall? If it's black, it's a vent and doesn't hook to anything. It's supposed to be open. Is the battery on the 240 on the driver's side? It's on the passenger side on mine. The only vac line that would be on the passenger side would be ALDA related, and shouldn't affect shut-down. Keep posting, I have pretty much rebuilt my whole vac system on mine, and I can help you. Many members will also be able to help.

I thought only the turbo cars have an ALDA?
The lines that pertain to engine shutoff are brown colored, if you can pull vacuum on the shutoff valve at the IP and it shuts off, check your system vacuum level, if you have good vacuum, or even weak but find no leaks, I would check under the dash @ the ignition switch to be sure the lines are still connected to it.

Samuel M. Ross · #6 10-22-2006, 03:28 AM

but let's concentrate on the IP/engine shut-off problem first. It was good advice that you NOT get sidetracked wondering why the black vacuum line terminates deadend under the dash. This is a vent and proper to not connect to anything. Oh yes, use golf tees to isolate the door-lock system so it will not adversely effect your progress. You can come back to it later.

IF you don't have one yet, a "mity vac" is a must on these cars... get one!
It's not clear who or how your IP/Engine shut-off device was pronounced to be good, but connecting a "mity vac" to this device with the engine running and pumping it will test it... and IF OK the engine should shut down as low as 5" of Hg.
IF it passes the test above, then restart the engine and then try the "mity vac" test again but this time on the brown line that goes through the firewall from the large main vacuum line that runs from the vacuum pump-to-brake chamber... and this time make sure the ignition switch is OFF. This test is to make sure the vacuum switch is OK that is coupled with the ignition switch.

Take a look at the photo at: http://ericandkat.com/mercedes/W123VacDoorLockDiag.JPG and you will see a neat way to reduce vacuum leaks on the many connectors that have not dried out and cracked but are just a little loose. Also deep in the bundle of vacuum lines you will see the brown vacuum line we were refering to that takes the vacuum into the ignition switch... eventually returning and connecting to the IP/engine shut-off device on the IP.
Keep those of us monitoring this THREAD informed of your progress so we can keep you on track.

Oh yes, later you can check out my Door Lock THREAD with diagram at:
http://www.peachparts.com/shopforum/showthread.php?t=160169
Regards,

1goos4u · #7 10-24-2006, 09:48 PM

Yes those black lines I was talking about were definitely the intentional vent lines. There is a vacuum line coming out of what appears to be the vacuum diaphragm (not sure if this is the correct term for this part) located behind the IP. I tested this line with a MityVac (true, definitely a must on this system) and it came up holding no vacuum at all. The engine was off for this test. Also I took off the instrument cluster and checked the vacuum lines connecting to the ignition switch, and they slipped out of their respective connections very easily, and were found to have oil residue in them. Would it make sense that the part I was talking about at the back of the IP went bad, lost vacuum, and then oil was sucked through the line?

dmorrison · #8 10-25-2006, 02:17 AM

Ok your Injection Pump shut off valve is bad.
A few clues for you. Brown colored plastic lines are for engine shutoff. Yellow based lines are for door locks. Green based lines are for Air Conditioning. Black lines are vent lines and one end would be un-connected, usually in the cabin dash area.

Attach your mity vac to the shutoff valve at the back of the Injection pump. Start the car. Apply vacuum to the unit with your mity vac. If the car shuts off immediately, then it is not the shutoff valve. If it does not, then it is bad. Use the "stop" lever to turn the engine off.
Now by what you have said. The valve went bad and it sucked oil into the brown line going the the ignition key shutoff valve and possibly onto the rest of the vacuum system.
You want to do a couple of things. Replace the shutoff valve. BE CAREFUL. doing it wrong can ruin the engine, due to a runaway engine. Here is my post on replacing the shutoff valve. Follow it and you will be fine.

http://www.peachparts.com/shopforum/showthread.php?t=151322&highlight=shutoff+valve+dave

Next you need to clean your hard plastic lines and determine how far the oil has traveled. The oil will ruin the vacuum elements and cause problems. Going line by line, disconnect them and clean them. I use brake cleaner spray (some may disagree with this using brake cleaner fluid, but I have had no problems doing this, allow it to completely dry). Check all the 2 way, 3 way and 4 way connectors and, replace them if necessary. You want a tight fit with the connectors and the plastic lines. If the oil has gotten all the way to the door locks then some more replacement, of the elements, may be necessary.

3rd, I know I said only two things. Place filters in your vacuum lines to determine if oil is leaking. The 2 places you can get oil is from the vacuum pump and the shutoff valve.
Install the filters as shown in the picture below. Use either lawn mower in line filters (clear )that will fit in the vacuum lines ( one between the shutoff valve and the dash and the other in one of the lines that comes off the vacuum pump to brake booster line.) You can also use Frame clear in line filters. Every time you check your oil level, you do check your oil level every time you fill up???. Check the inline filters for oil.

You should be set for a while until the next problem.

Dave

Samuel M. Ross · #9 10-25-2006, 03:20 AM

and while you are putting in those "in-line" fuel filters to serve as "tell-tales" for seeing oil in the vacuum system, I suggest you also add an "in-line" filter on the end of that vent line under the dash that goes nowhere! This will help keep dirt out of the vacuum system. This vent is probably where much of the air enters the vacuum control systems on these cars.
Regards